literature review current practices

• University of Texas Libraries

Literature Reviews

• What is a literature review?
• Steps in the Literature Review Process
• Define your research question
• Determine inclusion and exclusion criteria
• Choose databases and search
• Review Results
• Synthesize Results
• Analyze Results
• Librarian Support

What is a Literature Review?

A literature or narrative review is a comprehensive review and analysis of the published literature on a specific topic or research question. The literature that is reviewed contains: books, articles, academic articles, conference proceedings, association papers, and dissertations. It contains the most pertinent studies and points to important past and current research and practices. It provides background and context, and shows how your research will contribute to the field. 

A literature review should: 

• Provide a comprehensive and updated review of the literature;
• Explain why this review has taken place;
• Articulate a position or hypothesis;
• Acknowledge and account for conflicting and corroborating points of view

From  S age Research Methods

Purpose of a Literature Review

A literature review can be written as an introduction to a study to:

• Demonstrate how a study fills a gap in research
• Compare a study with other research that's been done

Or it can be a separate work (a research article on its own) which:

• Organizes or describes a topic
• Describes variables within a particular issue/problem

Limitations of a Literature Review

Some of the limitations of a literature review are:

• It's a snapshot in time. Unlike other reviews, this one has beginning, a middle and an end. There may be future developments that could make your work less relevant.
• It may be too focused. Some niche studies may miss the bigger picture.
• It can be difficult to be comprehensive. There is no way to make sure all the literature on a topic was considered.
• It is easy to be biased if you stick to top tier journals. There may be other places where people are publishing exemplary research. Look to open access publications and conferences to reflect a more inclusive collection. Also, make sure to include opposing views (and not just supporting evidence).

Source: Grant, Maria J., and Andrew Booth. “A Typology of Reviews: An Analysis of 14 Review Types and Associated Methodologies.” Health Information & Libraries Journal, vol. 26, no. 2, June 2009, pp. 91–108. Wiley Online Library, doi:10.1111/j.1471-1842.2009.00848.x.

Meryl Brodsky : Communication and Information Studies

Hannah Chapman Tripp : Biology, Neuroscience

Carolyn Cunningham : Human Development & Family Sciences, Psychology, Sociology

Larayne Dallas : Engineering

Janelle Hedstrom : Special Education, Curriculum & Instruction, Ed Leadership & Policy ​

Susan Macicak : Linguistics

Imelda Vetter : Dell Medical School

For help in other subject areas, please see the guide to library specialists by subject .

Periodically, UT Libraries runs a workshop covering the basics and library support for literature reviews. While we try to offer these once per academic year, we find providing the recording to be helpful to community members who have missed the session. Following is the most recent recording of the workshop, Conducting a Literature Review. To view the recording, a UT login is required.

• October 26, 2022 recording
• Last Updated: Oct 26, 2022 2:49 PM
• URL: https://guides.lib.utexas.edu/literaturereviews

Purdue Online Writing Lab Purdue OWL® College of Liberal Arts

Writing a Literature Review

Welcome to the Purdue OWL

This page is brought to you by the OWL at Purdue University. When printing this page, you must include the entire legal notice.

Copyright ©1995-2018 by The Writing Lab & The OWL at Purdue and Purdue University. All rights reserved. This material may not be published, reproduced, broadcast, rewritten, or redistributed without permission. Use of this site constitutes acceptance of our terms and conditions of fair use.

A literature review is a document or section of a document that collects key sources on a topic and discusses those sources in conversation with each other (also called synthesis ). The lit review is an important genre in many disciplines, not just literature (i.e., the study of works of literature such as novels and plays). When we say “literature review” or refer to “the literature,” we are talking about the research ( scholarship ) in a given field. You will often see the terms “the research,” “the scholarship,” and “the literature” used mostly interchangeably.

Where, when, and why would I write a lit review?

There are a number of different situations where you might write a literature review, each with slightly different expectations; different disciplines, too, have field-specific expectations for what a literature review is and does. For instance, in the humanities, authors might include more overt argumentation and interpretation of source material in their literature reviews, whereas in the sciences, authors are more likely to report study designs and results in their literature reviews; these differences reflect these disciplines’ purposes and conventions in scholarship. You should always look at examples from your own discipline and talk to professors or mentors in your field to be sure you understand your discipline’s conventions, for literature reviews as well as for any other genre.

A literature review can be a part of a research paper or scholarly article, usually falling after the introduction and before the research methods sections. In these cases, the lit review just needs to cover scholarship that is important to the issue you are writing about; sometimes it will also cover key sources that informed your research methodology.

Lit reviews can also be standalone pieces, either as assignments in a class or as publications. In a class, a lit review may be assigned to help students familiarize themselves with a topic and with scholarship in their field, get an idea of the other researchers working on the topic they’re interested in, find gaps in existing research in order to propose new projects, and/or develop a theoretical framework and methodology for later research. As a publication, a lit review usually is meant to help make other scholars’ lives easier by collecting and summarizing, synthesizing, and analyzing existing research on a topic. This can be especially helpful for students or scholars getting into a new research area, or for directing an entire community of scholars toward questions that have not yet been answered.

What are the parts of a lit review?

Most lit reviews use a basic introduction-body-conclusion structure; if your lit review is part of a larger paper, the introduction and conclusion pieces may be just a few sentences while you focus most of your attention on the body. If your lit review is a standalone piece, the introduction and conclusion take up more space and give you a place to discuss your goals, research methods, and conclusions separately from where you discuss the literature itself.

Introduction:

• An introductory paragraph that explains what your working topic and thesis is
• A forecast of key topics or texts that will appear in the review
• Potentially, a description of how you found sources and how you analyzed them for inclusion and discussion in the review (more often found in published, standalone literature reviews than in lit review sections in an article or research paper)
• Summarize and synthesize: Give an overview of the main points of each source and combine them into a coherent whole
• Analyze and interpret: Don’t just paraphrase other researchers – add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
• Critically Evaluate: Mention the strengths and weaknesses of your sources
• Write in well-structured paragraphs: Use transition words and topic sentence to draw connections, comparisons, and contrasts.

Conclusion:

• Summarize the key findings you have taken from the literature and emphasize their significance
• Connect it back to your primary research question

How should I organize my lit review?

Lit reviews can take many different organizational patterns depending on what you are trying to accomplish with the review. Here are some examples:

• Chronological : The simplest approach is to trace the development of the topic over time, which helps familiarize the audience with the topic (for instance if you are introducing something that is not commonly known in your field). If you choose this strategy, be careful to avoid simply listing and summarizing sources in order. Try to analyze the patterns, turning points, and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred (as mentioned previously, this may not be appropriate in your discipline — check with a teacher or mentor if you’re unsure).
• Thematic : If you have found some recurring central themes that you will continue working with throughout your piece, you can organize your literature review into subsections that address different aspects of the topic. For example, if you are reviewing literature about women and religion, key themes can include the role of women in churches and the religious attitude towards women.
• Qualitative versus quantitative research
• Empirical versus theoretical scholarship
• Divide the research by sociological, historical, or cultural sources
• Theoretical : In many humanities articles, the literature review is the foundation for the theoretical framework. You can use it to discuss various theories, models, and definitions of key concepts. You can argue for the relevance of a specific theoretical approach or combine various theorical concepts to create a framework for your research.

What are some strategies or tips I can use while writing my lit review?

Any lit review is only as good as the research it discusses; make sure your sources are well-chosen and your research is thorough. Don’t be afraid to do more research if you discover a new thread as you’re writing. More info on the research process is available in our "Conducting Research" resources .

As you’re doing your research, create an annotated bibliography ( see our page on the this type of document ). Much of the information used in an annotated bibliography can be used also in a literature review, so you’ll be not only partially drafting your lit review as you research, but also developing your sense of the larger conversation going on among scholars, professionals, and any other stakeholders in your topic.

Usually you will need to synthesize research rather than just summarizing it. This means drawing connections between sources to create a picture of the scholarly conversation on a topic over time. Many student writers struggle to synthesize because they feel they don’t have anything to add to the scholars they are citing; here are some strategies to help you:

• It often helps to remember that the point of these kinds of syntheses is to show your readers how you understand your research, to help them read the rest of your paper.
• Writing teachers often say synthesis is like hosting a dinner party: imagine all your sources are together in a room, discussing your topic. What are they saying to each other?
• Look at the in-text citations in each paragraph. Are you citing just one source for each paragraph? This usually indicates summary only. When you have multiple sources cited in a paragraph, you are more likely to be synthesizing them (not always, but often
• Read more about synthesis here.

The most interesting literature reviews are often written as arguments (again, as mentioned at the beginning of the page, this is discipline-specific and doesn’t work for all situations). Often, the literature review is where you can establish your research as filling a particular gap or as relevant in a particular way. You have some chance to do this in your introduction in an article, but the literature review section gives a more extended opportunity to establish the conversation in the way you would like your readers to see it. You can choose the intellectual lineage you would like to be part of and whose definitions matter most to your thinking (mostly humanities-specific, but this goes for sciences as well). In addressing these points, you argue for your place in the conversation, which tends to make the lit review more compelling than a simple reporting of other sources.

• UConn Library
• Literature Review: The What, Why and How-to Guide
• Introduction

Literature Review: The What, Why and How-to Guide — Introduction

• Getting Started
• How to Pick a Topic
• Strategies to Find Sources
• Evaluating Sources & Lit. Reviews
• Tips for Writing Literature Reviews
• Writing Literature Review: Useful Sites
• Citation Resources
• Other Academic Writings

What are Literature Reviews?

So, what is a literature review? "A literature review is an account of what has been published on a topic by accredited scholars and researchers. In writing the literature review, your purpose is to convey to your reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. As a piece of writing, the literature review must be defined by a guiding concept (e.g., your research objective, the problem or issue you are discussing, or your argumentative thesis). It is not just a descriptive list of the material available, or a set of summaries." Taylor, D.  The literature review: A few tips on conducting it . University of Toronto Health Sciences Writing Centre.

Goals of Literature Reviews

What are the goals of creating a Literature Review?  A literature could be written to accomplish different aims:

• To develop a theory or evaluate an existing theory
• To summarize the historical or existing state of a research topic
• Identify a problem in a field of research 

Baumeister, R. F., & Leary, M. R. (1997). Writing narrative literature reviews .  Review of General Psychology , 1 (3), 311-320.

What kinds of sources require a Literature Review?

• A research paper assigned in a course
• A thesis or dissertation
• A grant proposal
• An article intended for publication in a journal

All these instances require you to collect what has been written about your research topic so that you can demonstrate how your own research sheds new light on the topic.

Types of Literature Reviews

What kinds of literature reviews are written?

Narrative review: The purpose of this type of review is to describe the current state of the research on a specific topic/research and to offer a critical analysis of the literature reviewed. Studies are grouped by research/theoretical categories, and themes and trends, strengths and weakness, and gaps are identified. The review ends with a conclusion section which summarizes the findings regarding the state of the research of the specific study, the gaps identify and if applicable, explains how the author's research will address gaps identify in the review and expand the knowledge on the topic reviewed.

• Example : Predictors and Outcomes of U.S. Quality Maternity Leave: A Review and Conceptual Framework:  10.1177/08948453211037398  

Systematic review : "The authors of a systematic review use a specific procedure to search the research literature, select the studies to include in their review, and critically evaluate the studies they find." (p. 139). Nelson, L. K. (2013). Research in Communication Sciences and Disorders . Plural Publishing.

• Example : The effect of leave policies on increasing fertility: a systematic review:  10.1057/s41599-022-01270-w

Meta-analysis : "Meta-analysis is a method of reviewing research findings in a quantitative fashion by transforming the data from individual studies into what is called an effect size and then pooling and analyzing this information. The basic goal in meta-analysis is to explain why different outcomes have occurred in different studies." (p. 197). Roberts, M. C., & Ilardi, S. S. (2003). Handbook of Research Methods in Clinical Psychology . Blackwell Publishing.

• Example : Employment Instability and Fertility in Europe: A Meta-Analysis:  10.1215/00703370-9164737

Meta-synthesis : "Qualitative meta-synthesis is a type of qualitative study that uses as data the findings from other qualitative studies linked by the same or related topic." (p.312). Zimmer, L. (2006). Qualitative meta-synthesis: A question of dialoguing with texts .  Journal of Advanced Nursing , 53 (3), 311-318.

• Example : Women’s perspectives on career successes and barriers: A qualitative meta-synthesis:  10.1177/05390184221113735

Literature Reviews in the Health Sciences

• UConn Health subject guide on systematic reviews Explanation of the different review types used in health sciences literature as well as tools to help you find the right review type
• << Previous: Getting Started
• Next: How to Pick a Topic >>
• Last Updated: Sep 21, 2022 2:16 PM
• URL: https://guides.lib.uconn.edu/literaturereview

Harvey Cushing/John Hay Whitney Medical Library

• Collections
• Research Help

YSN Doctoral Programs: Steps in Conducting a Literature Review

• Biomedical Databases
• Global (Public Health) Databases
• Soc. Sci., History, and Law Databases
• Grey Literature
• Trials Registers
• Data and Statistics
• Public Policy
• Google Tips
• Recommended Books
• Steps in Conducting a Literature Review

What is a literature review?

A literature review is an integrated analysis -- not just a summary-- of scholarly writings and other relevant evidence related directly to your research question.  That is, it represents a synthesis of the evidence that provides background information on your topic and shows a association between the evidence and your research question.

A literature review may be a stand alone work or the introduction to a larger research paper, depending on the assignment.  Rely heavily on the guidelines your instructor has given you.

Why is it important?

A literature review is important because it:

• Explains the background of research on a topic.
• Demonstrates why a topic is significant to a subject area.
• Discovers relationships between research studies/ideas.
• Identifies major themes, concepts, and researchers on a topic.
• Identifies critical gaps and points of disagreement.
• Discusses further research questions that logically come out of the previous studies.

APA7 Style resources

APA Style Blog - for those harder to find answers

1. Choose a topic. Define your research question.

Your literature review should be guided by your central research question.  The literature represents background and research developments related to a specific research question, interpreted and analyzed by you in a synthesized way.

• Make sure your research question is not too broad or too narrow.  Is it manageable?
• Begin writing down terms that are related to your question. These will be useful for searches later.
• If you have the opportunity, discuss your topic with your professor and your class mates.

2. Decide on the scope of your review

How many studies do you need to look at? How comprehensive should it be? How many years should it cover? 

• This may depend on your assignment.  How many sources does the assignment require?

3. Select the databases you will use to conduct your searches.

Make a list of the databases you will search. 

Where to find databases:

• use the tabs on this guide
• Find other databases in the Nursing Information Resources web page
• More on the Medical Library web page
• ... and more on the Yale University Library web page

4. Conduct your searches to find the evidence. Keep track of your searches.

• Use the key words in your question, as well as synonyms for those words, as terms in your search. Use the database tutorials for help.
• Save the searches in the databases. This saves time when you want to redo, or modify, the searches. It is also helpful to use as a guide is the searches are not finding any useful results.
• Review the abstracts of research studies carefully. This will save you time.
• Use the bibliographies and references of research studies you find to locate others.
• Check with your professor, or a subject expert in the field, if you are missing any key works in the field.
• Ask your librarian for help at any time.
• Use a citation manager, such as EndNote as the repository for your citations. See the EndNote tutorials for help.

Review the literature

Some questions to help you analyze the research:

• What was the research question of the study you are reviewing? What were the authors trying to discover?
• Was the research funded by a source that could influence the findings?
• What were the research methodologies? Analyze its literature review, the samples and variables used, the results, and the conclusions.
• Does the research seem to be complete? Could it have been conducted more soundly? What further questions does it raise?
• If there are conflicting studies, why do you think that is?
• How are the authors viewed in the field? Has this study been cited? If so, how has it been analyzed?

Tips: 

• Review the abstracts carefully.  
• Keep careful notes so that you may track your thought processes during the research process.
• Create a matrix of the studies for easy analysis, and synthesis, across all of the studies.
• << Previous: Recommended Books
• Last Updated: Jan 4, 2024 10:52 AM
• URL: https://guides.library.yale.edu/YSNDoctoral

• Research article
• Open access
• Published: 16 May 2019

An analysis of current practices in undertaking literature reviews in nursing: findings from a focused mapping review and synthesis

• Helen Aveyard   ORCID: orcid.org/0000-0001-5133-3356 1 &
• Caroline Bradbury-Jones 2  

BMC Medical Research Methodology volume  19 , Article number:  105 ( 2019 ) Cite this article

39k Accesses

25 Citations

10 Altmetric

Metrics details

In this paper we discuss the emergence of many different methods for doing a literature review. Referring back to the early days, when there were essentially two types of review; a Cochrane systematic review and a narrative review, we identify how the term systematic review is now widely used to describe a variety of review types and how the number of available methods for doing a literature review has increased dramatically. This led us to undertake a review of current practice of those doing a literature review and the terms used to describe them.

We undertook a focused mapping review and synthesis. Literature reviews; defined as papers with the terms review or synthesis in the title, published in five nursing journals between January 2017–June 2018 were identified. We recorded the type of review and how these were undertaken.

We identified more than 35 terms used to describe a literature review. Some terms reflected established methods for doing a review whilst others could not be traced to established methods and/or the description of method in the paper was limited. We also found inconsistency in how the terms were used.

We have identified a proliferation of terms used to describe doing a literature review; although it is not clear how many distinct methods are being used. Our review indicates a move from an era when the term narrative review was used to describe all ‘non Cochrane’ reviews; to a time of expansion when alternative systematic approaches were developed to enhance rigour of such narrative reviews; to the current situation in which these approaches have proliferated to the extent so that the academic discipline of doing a literature review has become muddled and confusing. We argue that an ‘era of consolidation’ is needed in which those undertaking reviews are explicit about the method used and ensure that their processes can be traced back to a well described, original primary source.

Peer Review reports

Over the past twenty years in nursing, literature reviews have become an increasingly popular form of synthesising evidence and information relevant to the profession. Along with this there has been a proliferation of publications regarding the processes and practicalities of reviewing [ 1 , 2 , 3 , 4 ], This increase in activity and enthusiasm for undertaking literature reviews is paralleled by the foundation of the Cochrane Collaboration in 1993. Developed in response to the need for up-to-date reviews of evidence of the effectiveness of health care interventions, the Cochrane Collaboration introduced a rigorous method of searching, appraisal and analysis in the form of a ‘handbook’ for doing a systematic review [ 5 ] .Subsequently, similar procedural guidance has been produced, for example by the Centre for Reviews and Dissemination (CRD) [ 6 ] and The Joanna Briggs Institute [ 7 ]. Further guidance has been published to assist researchers with clarity in the reporting of published reviews [ 8 ].

In the early days of the literature review era, the methodological toolkit for those undertaking a literature was polarised, in a way that mirrored the paradigm wars of the time within mixed-methods research [ 9 ]. We refer to this as the ‘dichotomy era’ (i.e. the 1990s), The prominent methods of literature reviewing fell into one of two camps: The highly rigorous and systematic, mostly quantitative ‘Cochrane style’ review on one hand and a ‘narrative style’ review on the other hand, whereby a body of literature was summarised qualitatively, but the methods were often not articulated. Narrative reviews were particularly popular in dissertations and other student work (and they continue to be so in many cases) but have been criticised for a lack of systematic approach and consequently significant potential for bias in the findings [ 10 , 11 ].

The latter 1990s and early 2000, saw the emergence of other forms of review, developed as a response to the Cochrane/Narrative dichotomy. These alternative approaches to the Cochrane review provided researchers with reference points for performing reviews that drew on different study types, not just randomised controlled trials. They promoted a systematic and robust approach for all reviews, not just those concerned with effectiveness of interventions and treatments. One of the first published description of methods was Noblet and Hare’s (1998) ‘Meta-ethnography’ [ 12 ]. This method, although its name suggests otherwise, could incorporate and synthesise all types of qualitative research, not just ethnographies. The potential confusion regarding the inclusion of studies that were not ethnographies within a meta-ethnography, promoted the description of other similar methods, for example, the meta-synthesis of Walsh and Downe (2005) [ 13 ] and the thematic synthesis of Thomas and Harden (2008) [ 14 ]. Also, to overcome the dichotomy of the quantitative/qualitative reviews, the integrative review was described according to Whitemore and Knafl (2005) [ 15 ]. These reviews can be considered to be literature reviews that have been done in a systematic way but not necessarily adhering to guidelines established by the Cochrane Collaboration. We conceptualise this as the ‘expansion era’. Some of the methods are summarised in Table  1 .

Over the past two decades there has been a proliferation of review types, with corresponding explosion of terms used to describe them. A review of evidence synthesis methodologies by Grant and Booth in 2009 [ 20 ] identified 14 different approaches to reviewing the literature and similarly, Booth and colleagues [ 21 ] detailed 19 different review types, highlighting the range of review types currently available. We might consider this the ‘proliferation era’. This is however, somewhat a double-edged sword, because although researchers now have far more review methods at their disposal, there is risk of confusion in the field. As Sabatino and colleagues (2014) [ 22 ] have argued, review methods are not always consistently applied by researchers.

Aware of such potential inconsistency and also our own confusion at times regarding the range of review methods available, we questioned what was happening within our own discipline of nursing. We undertook a snap-shot, contemporary analysis to explore the range of terms used to describe reviews, the methods currently described in nursing and the underlying trends and patterns in searching, appraisal and analysis adopted by those doing a literature review. The aim was to gain some clarity on what is happening within the field, in order to understand, explain and critique what is happening within the proliferation era.

In order to explore current practices in doing a literature review, we undertook a ‘Focused Mapping Review and Synthesis’ (FMRS) – an approach that has been described only recently. This form of review [ 19 ] is a method of investigating trends in academic publications and has been used in a range of issues relevant to nursing and healthcare, for example, theory in qualitative research [ 23 ] and vicarious trauma in child protection research [ 24 ].

A FMRS seeks to identify what is happening within a particular subject or field of inquiry; hence the search is restricted to a particular time period and to pre-identified journals. The review has four distinct features: It: 1) focuses on identifying trends in an area rather than a body of evidence; 2) creates a descriptive map or topography of key features of research within the field rather than a synthesis of findings; 3) comments on the overall approach to knowledge production rather than the state of the evidence; 4) examines this within a broader epistemological context. These are translated into three specific focused activities: 1) targeted journals; 2) a specific subject; 3) a defined time period. The FMRS therefore, is distinct from other forms of review because it responds to questions concerned with ‘what is happening in this field?’ It was thus an ideal method to investigate current practices in literature reviews in nursing.

Using the international Scopus (2016) SCImago Journal and Country Rank, we identified the five highest ranked journals in nursing at that time of undertaking the review. There was no defined method for determining the number of journals to include in a review; the aim was to identify a sample and we identified five journals in order to search from a range of high ranking journals. We discuss the limitations of this later. Journals had to have ‘nursing’ or ‘nurse’ in the title and we did not include journals with a specialist focus, such as nutrition, cancer etcetera. The included journals are shown in Table  2 and are in order according to their ranking. We recognise that our journal choice meant that only articles published in English made it into the review.

A key decision in a FMRS is the time-period within which to retrieve relevant articles. Like many other forms of review, we undertook an initial scoping to determine the feasibility and parameters of the project [ 19 ]. In our previous reviews, the timeframe has varied from three months [ 23 ] to 6 years [ 24 ]. The main criterion is the likelihood for the timespan to contain sufficient articles to answer the review questions. We set the time parameter from January 2017–June 2018. We each took responsibility for two and three journals each from which to retrieve articles. We reviewed the content page of each issue of each journal. For our purposes, in order to reflect the diverse range of terms for describing a literature review, as described earlier in this paper, any paper that contained the term ‘review’ or ‘synthesis’ in the title was included in the review. This was done by each author individually but to enhance rigour, we worked in pairs to check each other’s retrieval processes to confirm inter-rater consistency. This process allowed any areas of uncertainty to be discussed and agreed and we found this form of calibration crucial to the process. The inclusion and exclusion criteria are shown in Table  3 .

Articles meeting the inclusion criteria, papers were read in full and data was extracted and recorded as per the proforma developed for the study (Table 4 ). The proforma was piloted on two papers to check for usability prior to data extraction. Data extraction was done independently but we discussed a selection of papers to enhance rigour of the process. No computer software was used in the analysis of the data. We did not critically appraise the included studies for quality because our purpose was to profile what is happening in the field rather than to draw conclusions from the included studies’ findings.

Once the details from all the papers had been extracted onto the tables, we undertook an analysis to identify common themes in the included articles. Because our aim was to produce a snap-shot profile, our analysis was thematic and conceptual. Although we undertook some tabulation and numerical analysis, our primary focus was on capturing patterns and trends characterised by the proliferation era. In line with the FMRS method, in the findings section we have used illustrative examples from the included articles that reflect and demonstrate the point or claim being made. These serve as useful sources of information and reference for readers seeking concrete examples.

Between January 2017 and June 2018 in the five journals we surveyed, a total of 222 papers with either ‘review’ or ‘synthesis’ in the title were retrieved and included in our analysis. We identified three primary themes: 1) Proliferation in names for doing a review; 2) Allegiance to an established review method; 3) Clarity about review processes. The results section is organised around these themes.

Proliferation in names for doing a review

We identified more than 35 terms used by authors to describe a literature review. Because we amalgamated terms such as ‘qualitative literature review’ and ‘qualitative review’ the exact number is actually slightly higher. It was clear from reading the reviews that many different terms were used to describe the same processes. For example qualitative systematic review, qualitative review and meta-synthesis, qualitative meta-synthesis, meta-ethnography all refer to a systematic review of qualitative studies. We have therefore grouped together the review types that refer to a particular type of review as described by the authors of the publications used in this study (Table  5 ).

In many reviews, the specific type of review was indicated in the title as seen for example in Table  5 . A striking feature was that all but two of the systematic reviews that contained a meta-analysis were labelled as such in the title; providing clarity and ease of retrieval. Where a literature review did not contain a meta-analysis, the title of the paper was typically referred to a ‘systematic review’; the implication being that a systematic review is not necessarily synonymous with a meta-analysis. However as discussed in the following section, this introduced some muddying of water, with different interpretations of what systematic review means and how broadly this term is applied. Some authors used the methodological type of included papers to describe their review. For example, a Cochrane-style systematic review was undertaken [ 25 ] but the reviewers did not undertake a meta-analysis and thus referred to their review as a ‘quantitative systematic review’.

Allegiance to an established literature review method

Many literature reviews demonstrated allegiance to a defined method and this was clearly and consistently described by the authors. For example, one team of reviewers [ 26 ] articulately described the process of a ‘meta-ethnography’ and gave a detailed description of their study and reference to the origins of the method by Noblet and Hare (1988) [ 12 ]. Another popular method was the ‘integrative review’ where most authors referred to the work of one or two seminal papers where the method was originally described (for example, Whitemore & Knafl 2005 [ 15 ]).

For many authors the term systematic review was used to mean a review of quantitative research, but some authors [ 27 , 28 , 29 ],used the term systematic review to describe reviews containing both qualitative and quantitative data.

However in many reviews, commitment to a method for doing a literature review appeared superficial, undeveloped and at times muddled. For example, three reviews [ 30 , 31 , 32 ] , indicate an integrative review in the title of their review, but this is the only reference to the method; there is no further reference to how the components of an integrative review are addressed within the paper. Other authors do not state allegiance to any particular method except to state a ‘literature review’ [ 33 ] but without an outline of a particular method for doing so. Anther review [ 34 ] reports a ‘narrative review’ but does not give further information about how this was done, possibly indicative of the lack of methods associated with the traditional narrative review. Three other reviewers documented how they searched, appraised and analysed their literature but do not reference an over-riding approach for their review [ 35 , 36 , 37 ]. In these examples, the review can be assumed to be a literature review, but the exact approach is not clear.

In other reviews, the methods for doing a literature review appear to be used interchangeably. For example in one review [ 38 ] the term narrative review was used in the title but in the main text an integrative review was described. In another review [ 39 ] two different and distinct methods were combined in a ‘meta-ethnographic meta-synthesis’.

Some authors [ 40 , 41 ] referred to a method used to undertake their review, for example a systematic review, but did not reference the primary source from where the method originated. Instead a secondary source, such as a textbook is used to reference the approach taken [ 20 , 42 ].

Clarity about review processes

Under this theme we discerned two principal issues: searching and appraisal. The majority of literature reviews contain three components- searching, appraisal and analysis, details of which are usually reported in the methods section of the papers. However, this is not always the case and for example, one review [ 43 ] provides only a search strategy with no information about the overall method or how critical appraisal or analysis were undertaken. Despite the importance of the process of analysis, we found little discussion of this in the papers reviewed.

The overwhelming trend for those doing a literature review was to describe a comprehensive search; although for many in our sample, a comprehensive search appeared to be limited to a database search; authors did not describe additional search strategies that would enable them to find studies that might be missed through electronic searching. Furthermore, authors did not define what a comprehensive search entailed, for example whether this included grey literature. We identified a very small number of studies where authors had undertaken a purposive sample [ 26 , 44 ]; in these reviews authors clearly stated that their search was for ‘seminal papers’ rather than all papers.

We reviewed the approaches to critical appraisal described in the papers and there were varying interpretations of what this means and which aspect of the included articles were to be subject to appraisal. Some authors [ 36 , 45 , 46 ] used the term ‘critical appraisal’ to refer to relevance of the paper to the review, rather than quality criteria. In that sense critical appraisal was used more as an inclusion criterion regarding relevance, rather than quality in the methods used. Mostly though, the term was used to describe the process of critical analysis of the methodological quality of included papers included in a review. When the term was used in this way to refer to quality criteria, appraisal tools were often used; for example, one review [ 47 ] provides a helpful example when they explain how a particular critical appraisal tool was used to asses the quality of papers in their review. Formal critical appraisal was undertaken by the vast majority reviewers, however the role of critical appraisal in the paper was often not explained [ 33 , 48 ]. It was common for a lot of detail to be provided about the approach to appraisal, including how papers were assessed and how disagreements between reviewers about the quality of individual papers were resolved, with no further mention of the subsequent role of the appraisal in the review. The reason for doing the critical appraisal in the review was often unclear and furthermore, in many cases, researchers included all papers within their review regardless of quality. For example, one team of reviewers [ 49 ] explained how the process, in their view, is not to exclude studies but to highlight the quality of evidence available. Another team of reviewers described how they did not exclude studies on the basis of quality because of the limited amount of research available on the topic [ 50 ].

Our review has identified a multiplicity of similar terms and approaches used by authors when doing a literature review, that we suggests marks the ‘proliferation era’. The expansion of terms used to describe a literature review has been observed previously [ 19 , 21 ]. We have identified an even wider range of terms, indicating that this trend may be increasing. This is likely to give the impression of an incoherent and potentially confusing approach to the scholarly undertaking of doing a literature review and is likely to be particularly problematic for novice researchers and students when attempting to grapple with the array of approaches available to them. The range of terms used in the title of papers to describe a literature review may cause both those new to research to wonder what the difference is between a qualitative evidence synthesis and a qualitative systematic review and which method is most suitable for their enquiry.

The clearest articles in our review were those that reported a systematic review with or without a meta-analysis. For example, one team of reviewers [ 25 ] undertook a Cochrane-style systematic review but did not undertake a meta-analysis and thus referred to their review as a ‘quantitative systematic review’. We found this form of labelling clear and helpful and is indeed in line with current recommendations [ 8 ]. While guidelines exist for the publication of systematic reviews [ 8 , 51 ], given the range of terms that are used by authors, some may be unclear when these guidelines should apply and this adds some confusion to the field. Of course, authors are at liberty to call their review processes whatever they deem appropriate, but our analysis has unearthed some inconsistencies that are confusing to the field of literature reviewing.

There is current debate about the status of literature reviews that are not ‘Cochrane’ style reviews [ 52 ]. Classification can be complex and whilst it might be tempting to refer to all non Cochrane-style reviews as ‘narrative reviews’ [ 52 ], literature reviews that conform to a recognised method would generally not be considered as such [ 53 ] and indeed the Cochrane Collaboration handbook refers to the principles of systematic review as applicable to different types of evidence, not just randomised controlled trials [ 5 ] .This raises the question as to whether the term systematic review should be an umbrella term referring to any review with an explicit method; which is implicit in the definition of a systematic review, but which raises the question as to how rigorous a method has to be to meet these standards, a thorny issue which we have identified in this study.

This review has identified a lack of detail in the reporting of the methods used by those doing a review. In 2017, Thorne raised the rhetorical question: ‘What kind of monster have we created?‘ [ 54 ]. Critiquing the growing investment in qualitative metasyntheses, she observed that many reviews were being undertaken that position themselves as qualitative metasyntheses, yet are theoretically and methodologically superficial. Thorne called for greater clarity and sense of purpose as the ‘trend in synthesis research marches forward’ [ 54 ]. Our review covered many review types, not just the qualitative meta-synthesis and its derivatives. However, we concur with Thorne’s conclusion that research methods are not extensively covered or debated in many of the published papers which might explain the confusion of terms and mixing of methods.

Despite the proliferation in terms for doing a literature review, and corresponding associated different methods and a lack of consistency in their application, our review has identified how the methods used (or indeed the reporting of the methods) appear to be remarkably similar in most publications. This may be due to limitations in the word count available to authors. However for example, the vast majority of papers describe a comprehensive search, critical appraisal and analysis. The approach to searching is of particular note; whilst comprehensive searching is the cornerstone of the Cochrane approach, other aproaches advocate that a sample of literature is sufficient [ 15 , 20 ]. Yet in our review we found only two examples where reviewers had used this approach, despite many other reviews claiming to be undertaking a meta-ethnography or meta-synthesis. This indicates that many of those doing a literature review have defaulted to the ‘comprehensive search’ irrespective of the approach to searching suggested in any particular method which is again indicative of confusion in the field.

Differences are reported in the approach to searching and critical appraisal and these appear not to be linked to different methods, but seem to be undertaken on the judgement and discretion of the reviewers without rationale or justification within the published paper. It is not for us to question researchers’ decisions as regards managing the flow of articles through their reviews, but when it comes to the issue of both searching and lack of clarity about the role of critical appraisal there is evidence of inconsistency by those doing a literature review. This reflects current observations in the literature where the lack of clarity about the role of critical appraisal within a literature review is debated . [ 55 , 56 ].

Our review indicates that many researchers follow a very similar process, regardless of their chosen method and the real differences that do exist between published methods are not apparent in many of the published reviews. This concurs with previously mentioned concerns [ 54 ] about the superficial manner in which methods are explored within literature reviews. The overriding tendency is to undertake a comprehensive review, critical appraisal and analysis, following the formula prescribed by Cochrane, even if this is not required by the literature review method stated in the paper. Other researchers [ 52 ] have questioned whether the dominance of the Cochrane review should be questioned. We argue that emergence of different methods for doing a literature review in a systematic way has indeed challenged the perceived dominance of the Cochrane approach that characterised the dichotomy era, where the only alternative was a less rigourous and often poorly described process of dealing with literature. It is positive that there is widespread acknowledgement of the validity of other approaches. But we argue that the expansion era, whereby robust processes were put forward as alternatives that filled the gap left by polarisation, has gone too far. The magnitude in the number of different approaches identified in this review has led to a confused field. Thorne [ 54 ] refers to a ‘meta-madness’; with the proliferation of methods leading to the oversimplification of complex literature and ideas. We would extend this to describe a ‘meta-muddle’ in which, not only are the methods and results oversimplified, but the existence of so many terms used to describe a literature review, many of them used interchangeably, has added a confusion to the field and prevented the in-depth exploration and development of specific methods. Table  6 shows the issues associated with the proliferation era and importantly, it also highlights the recommendations that might lead to a more coherent reviewing community in nursing.

The terms used for doing a literature review are often used both interchangeably and inconsistently, with minimal description of the methods undertaken. It is not surprising therefore that some journal editors do not index these consistently within the journal. For example, in one edition of one journal included in the review, there are two published integrative reviews. One is indexed in the section entitled as a ‘systematic review’, while the other is indexed in a separate section entitled ‘literature review’. In another edition of a journal, two systematic reviews with meta-analysis are published. One is listed as a research article and the other as a review and discussion paper. It seems to us then, that editors and publishers might sometimes also be confused and bewildered themselves.

Whilst guidance does exist for the publication of some types of systematic reviews in academic journals; for example the PRISMA statement [ 8 ] and Entreq guidelines [ 51 ], which are specific to particular qualitative synthesis, guidelines do not exist for each approach. As a result, for those doing an alternative approach to their literature review, for example an integrative review [ 15 ], there is only general publication guidance to assist. In the current reviewing environment, there are so many terms, that more specific guidance would be impractical anyway. However, greater clarity about the methods used and halting the introduction of different terms to mean the same thing will be helpful.

Limitations

This study provides a snapshot of the way in which literature reviews have been described within a short publication timeframe. We were limited for practical reasons to a small section of high impact journals. Including a wider range of journals would have enhanced the transferability of the findings. Our discussion is, of course, limited to the review types that were published in the timeframe, in the identified journals and which had the term ‘review’ or ‘synthesis’ in the title. This would have excluded papers that were entitled ‘meta-analysis’. However as we were interested in the range of reviews that fall outside the scope of a meta-analysis, we did not consider that this limited the scope of the paper. Our review is further limited by the lack of detail of the methods undertaken provided in many of the papers reviewed which, although providing evidence for our arguments, also meant that we had to assume meaning that was unclear from the text provided.

The development of rigorous methods for doing a literature review is to be welcomed; not all review questions can be answered by Cochrane style reviews and robust methods are needed to answer review questions of all types. Therefore whilst we welcome the expansion in methods for doing a literature review, the proliferation in the number of named approaches should be, in our view, a cause for reflection. The increase in methods could be indicative of an emerging variation in possible approaches; alternatively, the increase could be due to a lack of conceptual clarity where, on closer inspection, the methods do not differ greatly and could indeed be merged. Further scrutiny of the methods described within many papers support the latter situation but we would welcome further discussion about this. Meanwhile, we urge researchers to make careful consideration of the method they adopt for doing a literature review, to justify this approach carefully and to adhere closely to its method. Having witnessed an era of dichotomy, expansion and proliferation of methods for doing a literature review, we now seek a new era of consolidation.

Bettany-Saltikov J. How to do a systematic literature review in nursing: a step-by-step guide. Maidenhead: Open University Press; 2012.

Google Scholar  

Coughlan M, Cronin P, Ryan F. Doing a literature review in nursing, Health and social care. London: Sage; 2013.

Aveyard H. Doing a literature review in health and social care. Maidenhead: Open University Press; 2018.

Davis D. A practical overview of how to conduct a systematic review. Nurs Stand. 2016;31(12):60–70.

Article   Google Scholar  

Higgins and Green. Cochrane handbook for systematic reviews of interventions version 5.1.0: Cochrane Collaboration; 2011.

Centre for Reviews and Dissemination. Systematic Reviews: CRD's guidance for undertaking reviews in health care. York: University of York; 2008.

Aromataris E, Munn Z, editors. Joanna Briggs Institute Reviewer's Manual: The Joanna Briggs Institute; 2017. Available from https://reviewersmanual.joannabriggs.org/

Shamseer L, Moher D, Clarke M, Ghersi D, Liberati A, Petticrew M, Shekelle P, Stewart L. Preferred reporting items for systematic review and meta-analysis protocols. Br Med J. 2015;2:349 (Jan 02).

Creswell JW, Plano-Clark VL. Designing and conducting mixed methods research. 2nd ed. Thousand Oaks: Sage Publications; 2011.

Greenhalgh T. How to read a paper. 4th ed: Wiley; 2010.

Booth A, Papaioannou D, Sutton A. Systematic appproaches to a successful literature review Sage London; 2012.

Noblit GW, Hare RD. Meta-ethnography, synthesising qualitative studies, qualitative research methods, volume 11. London: SAGE Publications; 1988.

Walsh D, Downe S. Meta-synthesis method for qualitative research: a literature review. J Adv Nurs. 2005;50(2):204–11.

Thomas J, Harden A. Methods for the thematic synthesis of qualitative research in systematic reviews. BMC Med Res Methodol. 2008;8:45.

Whittemore R, Knafl K. The integrative review: updated methodology. J Adv Nurs. 2005;52:546–53.

Scoping Peters MDJ, Godfrey CM, McInerney P, Soares CB, Khalil H, Parker D. Methodology for Joanna Briggs institute scoping review. Joanna Briggs institute reviewers manual: Australia; 2015.

Wong G, Greenhalgh T, Westhorp G, Buckingham J, Pawson R. RAMESES publication standards: realist synthesis BMC medicine, vol. 11; 2013. p. 21.

Plüddemann A, Aronson JK, Onakpoya I, Heneghan C, Mahtani KR. Redefining rapid reviews: a flexible framework for restricted systematic reviews. BMJ Evidence-Based Medicine Epub ahead of print: 27 June 2018. https://doi.org/10.1136/bmjemb-2018-110990 .

Bradbury-Jones C, Breckenridge J, Clark MT, Herber OR, Jones C, Taylor J. Advancing the science of literature reviewing: the focused mapping review and synthesis as a novel approach. Int J Soc Res Methodol. https://doi.org/10.1080/13645579.2019.1576328 .

Grant MJ, Booth A. A typology of review- an analysis of 14 review types and associated methodologies. Health Info Libr J. 2009;26(2):91–108.

Booth, A., Noyes, J., Flemming, K., Gerhardus, A., Wahlster, P., van der Wilt G.J., Mozygemba K, Refolo P, Sacchini D, Tummers, M, Rehfuess, E. (2016) Guidance on choosing qualitative evidence synthesis methods for use in health technology assessments of complex interventions. Available: http://www.integrate-hta.eu/wp-content/uploads/2016/02/Guidance-on-choosing-qualitative-evidence-synthesis-methods-for-use-in-HTA-of-complex-interventions.pdf

Sabatino L, Stievano A, Rocco G, Kallio H, Pietila A, KAngasniemi M. The dignity of the nursing profession: a meta-synthesis of qualitative research. Nurs Ethics. 2014;2(6):659–72.

Bradbury-Jones C, Taylor J, Herber O. How theory is used and articulated in qualitative research: development of a new typology. Soc Sci Med. 2014;120:135–41.

Taylor J, Bradbury-Jones C, Breckenridge J, Jones C, Herber OR. Risk of vicarious trauma in nursing research: a focused mapping review and synthesis. J Clin Nurs. 2016. https://doi.org/10.1111/jocn.13235 .

Haggman Laitila A, Rompannen J. Outcomes of interventions for nurse leaders’ well being at work. A quantitative systematic review. J Adv Nurs. 2018;74:34–44.

Strandos M, Bondas T. The nurse patient relationship as a story of health enhancement in community care- a meta-ethnography. J Adv Nurs. 2018;74:11–8.

Gilissen J, Pivodic L, Smets T, Gastmans C, Stichels RV, Delieus L, Van den Black L. Preconditions for successful advanced care planning in nursing homes: a systematic review. Int J Nurs Stud. 2017;66:47–59.

Walczak A, Mcdonald F, Patterson P, Dobinson K, Kimberley A. How does parental cancer affect adolescent and young adult offspring. A systematic review. Int J Nurs Stud. 2018;77:54–80.

Leyva-Moral JM, Palmoero PA, Feijoo-Cid M, Edwards JE. Reproductive decision making in women living with HIV: systematic review. Int J Nurs Stud. 2018;77:207–21.

Pires S, Monteiro S, Pereira A, Chaló D, Melo E, Rodriguese A. Non technical skills assessment for pre-licensure nursing students: an integrative literature review nurse education today, vol. 58; 2017. p. 19–24.

Wilkinson A, Meilkle N, Law P, Yong A, Butler P, Kim J, Mulligan H, Hale L. How older adults and their informal carers prevent falls: an integrative review. Int J Nurs Stud. 2018;82:13–8.

Drewniak D, Krones T, Wild V. Do attitudes and behaviours of health care professionals exacerbate health care disparities among immigrant and ethnic minority groups? An integrative literature review. Int J Nurs Stud. 2017;70:89–98.

Garone A, Craen Van de P. The role of language skills abd internationalisation in nursing degree programmes: a literature review. Nurse Educ Today. 2017;49:140–4.

Casey M, O’Connor L, Cashin A (et al) An overview of the outcomes and impact of specialist and advanced nursing and midwifery practice on quality of care, cost and access to services: A narrative review. Nurse Educ Today 2017;56:35-40.

Adib-Hajbaghery M, Sharifi N. Effect of simulation training on the development of nurses and nursing students critical thinking: a systematic review. Nurse Educ Today. 2017;50:17–24.

Irwin C, Bliss J, Poole J. Does preceptorship improve confidence and competence in newly qualified nurses: a systematic literature review. Nurse educ Today. 2018;60:35–46.

Jefferies D, McNallya S, Roberts K, Wallace A, Stunden A, D'Souzaa S, Glew P. The importance of academic literacy for undergraduate nursing students and its relationship to future professional clinical practice: a systematic review. Nurse educ Today. 2018;60:84–91.

Lewis ML, Neville C, Ashkanasy NM. Emotional intelligence and affective events in nurse education- a narrative review. Nurse Educ Today. 2017;53:34–40.

Jensen D, Sorensen A. Nurses experiences of working in organisations undergoing restructuring: a meta-synthesis of qualitative research studies. Int J Nurs Stud. 2017;66:7–14.

Milligan F, Wareing M, Preston-Shoot M, Pappas Y, Randhawa G, Bhandol J. Supporting nursing, midwifery and allied health professional students to raise concerns with the quality of care: a review of the research literature. Nurse Educ Today. 2017;57:29–39.

Rozendo CA, Salas AS. A critical review of social and health inequalities in the nursing curriculum. Nurse Educ Today. 2017;50:62–71.

Kiteley R, Stogdon C. Literature reviews in social work. London: Sage; 2014.

Book   Google Scholar  

Rebeiro G, Evans A, Edward K, Chapman R. Registered nurse buddies. Educators by proxy? Nurse Educ Today. 2017;55:1–4.

Sinclair S, Raffin Bouchal S, Venturato L, Milsonic-Kondejewski J, Smith Macdonald L. Compassion fatigue: a meta-narrative review of the health care literature. Int J Nurs Stud. 2017;69:9–24.

Hovey S, Dyck MJ, Reese C, Myoung JK. Nursing students’ attitudes towards persons who are aged: an integrative review. J Adv Nurs. 2017;49:145–52.

Granheim B, Shaw J, Mansah M. Use of interprofessional learning and simulation in undergraduate nursing programmes to address interprofessional communication and collaboration- an integrative review. Nurse Educ Today. 2018;62:118–27.

Philips P, Lumley E, Duncan R, Aber A, Buckley Woods H, Jones GC. A systematic review of qualitative research into people’s experiences of living with venous leg ulcers. J Adv Nurs. 2018;74:550–63.

Slater CE, Cusick A. Factors relating to self directed learning readiness of students in health professional programmes a scoping review. Nurse Educ Today. 2017;52:22–33.

Vanderspank-Wright B, Efstathiou N, Vandjk A. Critical care nurses experience of withdrawing treatment: a systematic review of qualitative evidence. Int J Nurs Stud. 2018;77:15–26.

Kelly M, Wills J, Sykes S. Do nurses’ personal health behaviours impact their health promotion practice? A systematic review. Int J Nurs Stud. 2017;76:62–77.

Tong A, Flemming K, McInnes E, Oliver S, Craig J. Enhancing transparency in the reporting in the synthesis of qualitative research. BMC Med Res Methodol. 2012;12(1):181.

Greenhalgh T, Thorne S, Malterud K. Time to challenge the spurious hierarchy of systematic over narrative reviews? Eur J Clin Investig. 2018. https://doi.org/10.1111/eci12931 .

Aveyard H, Payne S, Preston N. A postgraduate’s guide to doing a literature review. Maidenhead: Open University Press; 2016.

Thorne S. Metasynthetic madness: what kind of monster have we created? Qual Health Res. 2017;27(1):3–12.

Sibeoni J, Orri M, Colin S, Valentin M, Pradere J, Revah-Levy A. The lived experience of anorexia nervosa in adolescence, comparison of parents’ view of adolescence, parents and professionals: a meta-synthesis. Int J Nurs Stud. 2017;65:25–34.

Nightingale S, Spiby H, Sheen K, Slade P. The impact of emotional intelligence in long term health care professionals on caring behaviours towards patients in clinical and long term settings. Integrative review. Int J Nurs Stud. 2018;80:106–17.

Download references

Acknowledgements

Availability of data and materials.

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Author information

Authors and affiliations.

Faculty of Health and Life Sciences, Oxford Brookes University, Jack Straw’s Lane, Oxford, OX3 0FL, England, UK

Helen Aveyard

University of Birmingham, Birmingham, England, UK

Caroline Bradbury-Jones

You can also search for this author in PubMed   Google Scholar

Contributions

Both HA and CB-J contributed to the data collection and analysis. HA wrote the paper and CB-J commented on the drafts. HA revised the paper according to the reviewers’ comments and CB-J commented on these revisions 30/4/19. Both authors read and approved the final manuscript.

Corresponding author

Correspondence to Helen Aveyard .

Ethics declarations

Ethics approval and consent to participate.

not applicable.

Consent for publication

Competing interests, publisher’s note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/ ), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/ ) applies to the data made available in this article, unless otherwise stated.

Reprints and permissions

About this article

Cite this article.

Aveyard, H., Bradbury-Jones, C. An analysis of current practices in undertaking literature reviews in nursing: findings from a focused mapping review and synthesis. BMC Med Res Methodol 19 , 105 (2019). https://doi.org/10.1186/s12874-019-0751-7

Download citation

Received : 16 December 2018

Accepted : 07 May 2019

Published : 16 May 2019

DOI : https://doi.org/10.1186/s12874-019-0751-7

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

• Evidence synthesis
• Literature review
• Meta-ethnography
• Systematic review

BMC Medical Research Methodology

ISSN: 1471-2288

• General enquiries: [email protected]

• USC Libraries
• Research Guides

Organizing Your Social Sciences Research Paper

• 5. The Literature Review
• Purpose of Guide
• Design Flaws to Avoid
• Independent and Dependent Variables
• Glossary of Research Terms
• Reading Research Effectively
• Narrowing a Topic Idea
• Broadening a Topic Idea
• Extending the Timeliness of a Topic Idea
• Academic Writing Style
• Applying Critical Thinking
• Choosing a Title
• Making an Outline
• Paragraph Development
• Research Process Video Series
• Executive Summary
• The C.A.R.S. Model
• Background Information
• The Research Problem/Question
• Theoretical Framework
• Citation Tracking
• Content Alert Services
• Evaluating Sources
• Primary Sources
• Secondary Sources
• Tiertiary Sources
• Scholarly vs. Popular Publications
• Qualitative Methods
• Quantitative Methods
• Insiderness
• Using Non-Textual Elements
• Limitations of the Study
• Common Grammar Mistakes
• Writing Concisely
• Avoiding Plagiarism
• Footnotes or Endnotes?
• Further Readings
• Generative AI and Writing
• USC Libraries Tutorials and Other Guides
• Bibliography

A literature review surveys prior research published in books, scholarly articles, and any other sources relevant to a particular issue, area of research, or theory, and by so doing, provides a description, summary, and critical evaluation of these works in relation to the research problem being investigated. Literature reviews are designed to provide an overview of sources you have used in researching a particular topic and to demonstrate to your readers how your research fits within existing scholarship about the topic.

Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . Fourth edition. Thousand Oaks, CA: SAGE, 2014.

Importance of a Good Literature Review

A literature review may consist of simply a summary of key sources, but in the social sciences, a literature review usually has an organizational pattern and combines both summary and synthesis, often within specific conceptual categories . A summary is a recap of the important information of the source, but a synthesis is a re-organization, or a reshuffling, of that information in a way that informs how you are planning to investigate a research problem. The analytical features of a literature review might:

• Give a new interpretation of old material or combine new with old interpretations,
• Trace the intellectual progression of the field, including major debates,
• Depending on the situation, evaluate the sources and advise the reader on the most pertinent or relevant research, or
• Usually in the conclusion of a literature review, identify where gaps exist in how a problem has been researched to date.

Given this, the purpose of a literature review is to:

• Place each work in the context of its contribution to understanding the research problem being studied.
• Describe the relationship of each work to the others under consideration.
• Identify new ways to interpret prior research.
• Reveal any gaps that exist in the literature.
• Resolve conflicts amongst seemingly contradictory previous studies.
• Identify areas of prior scholarship to prevent duplication of effort.
• Point the way in fulfilling a need for additional research.
• Locate your own research within the context of existing literature [very important].

Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper. 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Jesson, Jill. Doing Your Literature Review: Traditional and Systematic Techniques . Los Angeles, CA: SAGE, 2011; Knopf, Jeffrey W. "Doing a Literature Review." PS: Political Science and Politics 39 (January 2006): 127-132; Ridley, Diana. The Literature Review: A Step-by-Step Guide for Students . 2nd ed. Los Angeles, CA: SAGE, 2012.

Types of Literature Reviews

It is important to think of knowledge in a given field as consisting of three layers. First, there are the primary studies that researchers conduct and publish. Second are the reviews of those studies that summarize and offer new interpretations built from and often extending beyond the primary studies. Third, there are the perceptions, conclusions, opinion, and interpretations that are shared informally among scholars that become part of the body of epistemological traditions within the field.

In composing a literature review, it is important to note that it is often this third layer of knowledge that is cited as "true" even though it often has only a loose relationship to the primary studies and secondary literature reviews. Given this, while literature reviews are designed to provide an overview and synthesis of pertinent sources you have explored, there are a number of approaches you could adopt depending upon the type of analysis underpinning your study.

Argumentative Review This form examines literature selectively in order to support or refute an argument, deeply embedded assumption, or philosophical problem already established in the literature. The purpose is to develop a body of literature that establishes a contrarian viewpoint. Given the value-laden nature of some social science research [e.g., educational reform; immigration control], argumentative approaches to analyzing the literature can be a legitimate and important form of discourse. However, note that they can also introduce problems of bias when they are used to make summary claims of the sort found in systematic reviews [see below].

Integrative Review Considered a form of research that reviews, critiques, and synthesizes representative literature on a topic in an integrated way such that new frameworks and perspectives on the topic are generated. The body of literature includes all studies that address related or identical hypotheses or research problems. A well-done integrative review meets the same standards as primary research in regard to clarity, rigor, and replication. This is the most common form of review in the social sciences.

Historical Review Few things rest in isolation from historical precedent. Historical literature reviews focus on examining research throughout a period of time, often starting with the first time an issue, concept, theory, phenomena emerged in the literature, then tracing its evolution within the scholarship of a discipline. The purpose is to place research in a historical context to show familiarity with state-of-the-art developments and to identify the likely directions for future research.

Methodological Review A review does not always focus on what someone said [findings], but how they came about saying what they say [method of analysis]. Reviewing methods of analysis provides a framework of understanding at different levels [i.e. those of theory, substantive fields, research approaches, and data collection and analysis techniques], how researchers draw upon a wide variety of knowledge ranging from the conceptual level to practical documents for use in fieldwork in the areas of ontological and epistemological consideration, quantitative and qualitative integration, sampling, interviewing, data collection, and data analysis. This approach helps highlight ethical issues which you should be aware of and consider as you go through your own study.

Systematic Review This form consists of an overview of existing evidence pertinent to a clearly formulated research question, which uses pre-specified and standardized methods to identify and critically appraise relevant research, and to collect, report, and analyze data from the studies that are included in the review. The goal is to deliberately document, critically evaluate, and summarize scientifically all of the research about a clearly defined research problem . Typically it focuses on a very specific empirical question, often posed in a cause-and-effect form, such as "To what extent does A contribute to B?" This type of literature review is primarily applied to examining prior research studies in clinical medicine and allied health fields, but it is increasingly being used in the social sciences.

Theoretical Review The purpose of this form is to examine the corpus of theory that has accumulated in regard to an issue, concept, theory, phenomena. The theoretical literature review helps to establish what theories already exist, the relationships between them, to what degree the existing theories have been investigated, and to develop new hypotheses to be tested. Often this form is used to help establish a lack of appropriate theories or reveal that current theories are inadequate for explaining new or emerging research problems. The unit of analysis can focus on a theoretical concept or a whole theory or framework.

NOTE : Most often the literature review will incorporate some combination of types. For example, a review that examines literature supporting or refuting an argument, assumption, or philosophical problem related to the research problem will also need to include writing supported by sources that establish the history of these arguments in the literature.

Baumeister, Roy F. and Mark R. Leary. "Writing Narrative Literature Reviews."  Review of General Psychology 1 (September 1997): 311-320; Mark R. Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Kennedy, Mary M. "Defining a Literature." Educational Researcher 36 (April 2007): 139-147; Petticrew, Mark and Helen Roberts. Systematic Reviews in the Social Sciences: A Practical Guide . Malden, MA: Blackwell Publishers, 2006; Torracro, Richard. "Writing Integrative Literature Reviews: Guidelines and Examples." Human Resource Development Review 4 (September 2005): 356-367; Rocco, Tonette S. and Maria S. Plakhotnik. "Literature Reviews, Conceptual Frameworks, and Theoretical Frameworks: Terms, Functions, and Distinctions." Human Ressource Development Review 8 (March 2008): 120-130; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016.

Structure and Writing Style

I.  Thinking About Your Literature Review

The structure of a literature review should include the following in support of understanding the research problem :

• An overview of the subject, issue, or theory under consideration, along with the objectives of the literature review,
• Division of works under review into themes or categories [e.g. works that support a particular position, those against, and those offering alternative approaches entirely],
• An explanation of how each work is similar to and how it varies from the others,
• Conclusions as to which pieces are best considered in their argument, are most convincing of their opinions, and make the greatest contribution to the understanding and development of their area of research.

The critical evaluation of each work should consider :

• Provenance -- what are the author's credentials? Are the author's arguments supported by evidence [e.g. primary historical material, case studies, narratives, statistics, recent scientific findings]?
• Methodology -- were the techniques used to identify, gather, and analyze the data appropriate to addressing the research problem? Was the sample size appropriate? Were the results effectively interpreted and reported?
• Objectivity -- is the author's perspective even-handed or prejudicial? Is contrary data considered or is certain pertinent information ignored to prove the author's point?
• Persuasiveness -- which of the author's theses are most convincing or least convincing?
• Validity -- are the author's arguments and conclusions convincing? Does the work ultimately contribute in any significant way to an understanding of the subject?

II.  Development of the Literature Review

Four Basic Stages of Writing 1.  Problem formulation -- which topic or field is being examined and what are its component issues? 2.  Literature search -- finding materials relevant to the subject being explored. 3.  Data evaluation -- determining which literature makes a significant contribution to the understanding of the topic. 4.  Analysis and interpretation -- discussing the findings and conclusions of pertinent literature.

Consider the following issues before writing the literature review: Clarify If your assignment is not specific about what form your literature review should take, seek clarification from your professor by asking these questions: 1.  Roughly how many sources would be appropriate to include? 2.  What types of sources should I review (books, journal articles, websites; scholarly versus popular sources)? 3.  Should I summarize, synthesize, or critique sources by discussing a common theme or issue? 4.  Should I evaluate the sources in any way beyond evaluating how they relate to understanding the research problem? 5.  Should I provide subheadings and other background information, such as definitions and/or a history? Find Models Use the exercise of reviewing the literature to examine how authors in your discipline or area of interest have composed their literature review sections. Read them to get a sense of the types of themes you might want to look for in your own research or to identify ways to organize your final review. The bibliography or reference section of sources you've already read, such as required readings in the course syllabus, are also excellent entry points into your own research. Narrow the Topic The narrower your topic, the easier it will be to limit the number of sources you need to read in order to obtain a good survey of relevant resources. Your professor will probably not expect you to read everything that's available about the topic, but you'll make the act of reviewing easier if you first limit scope of the research problem. A good strategy is to begin by searching the USC Libraries Catalog for recent books about the topic and review the table of contents for chapters that focuses on specific issues. You can also review the indexes of books to find references to specific issues that can serve as the focus of your research. For example, a book surveying the history of the Israeli-Palestinian conflict may include a chapter on the role Egypt has played in mediating the conflict, or look in the index for the pages where Egypt is mentioned in the text. Consider Whether Your Sources are Current Some disciplines require that you use information that is as current as possible. This is particularly true in disciplines in medicine and the sciences where research conducted becomes obsolete very quickly as new discoveries are made. However, when writing a review in the social sciences, a survey of the history of the literature may be required. In other words, a complete understanding the research problem requires you to deliberately examine how knowledge and perspectives have changed over time. Sort through other current bibliographies or literature reviews in the field to get a sense of what your discipline expects. You can also use this method to explore what is considered by scholars to be a "hot topic" and what is not.

III.  Ways to Organize Your Literature Review

Chronology of Events If your review follows the chronological method, you could write about the materials according to when they were published. This approach should only be followed if a clear path of research building on previous research can be identified and that these trends follow a clear chronological order of development. For example, a literature review that focuses on continuing research about the emergence of German economic power after the fall of the Soviet Union. By Publication Order your sources by publication chronology, then, only if the order demonstrates a more important trend. For instance, you could order a review of literature on environmental studies of brown fields if the progression revealed, for example, a change in the soil collection practices of the researchers who wrote and/or conducted the studies. Thematic [“conceptual categories”] A thematic literature review is the most common approach to summarizing prior research in the social and behavioral sciences. Thematic reviews are organized around a topic or issue, rather than the progression of time, although the progression of time may still be incorporated into a thematic review. For example, a review of the Internet’s impact on American presidential politics could focus on the development of online political satire. While the study focuses on one topic, the Internet’s impact on American presidential politics, it would still be organized chronologically reflecting technological developments in media. The difference in this example between a "chronological" and a "thematic" approach is what is emphasized the most: themes related to the role of the Internet in presidential politics. Note that more authentic thematic reviews tend to break away from chronological order. A review organized in this manner would shift between time periods within each section according to the point being made. Methodological A methodological approach focuses on the methods utilized by the researcher. For the Internet in American presidential politics project, one methodological approach would be to look at cultural differences between the portrayal of American presidents on American, British, and French websites. Or the review might focus on the fundraising impact of the Internet on a particular political party. A methodological scope will influence either the types of documents in the review or the way in which these documents are discussed.

Other Sections of Your Literature Review Once you've decided on the organizational method for your literature review, the sections you need to include in the paper should be easy to figure out because they arise from your organizational strategy. In other words, a chronological review would have subsections for each vital time period; a thematic review would have subtopics based upon factors that relate to the theme or issue. However, sometimes you may need to add additional sections that are necessary for your study, but do not fit in the organizational strategy of the body. What other sections you include in the body is up to you. However, only include what is necessary for the reader to locate your study within the larger scholarship about the research problem.

Here are examples of other sections, usually in the form of a single paragraph, you may need to include depending on the type of review you write:

• Current Situation : Information necessary to understand the current topic or focus of the literature review.
• Sources Used : Describes the methods and resources [e.g., databases] you used to identify the literature you reviewed.
• History : The chronological progression of the field, the research literature, or an idea that is necessary to understand the literature review, if the body of the literature review is not already a chronology.
• Selection Methods : Criteria you used to select (and perhaps exclude) sources in your literature review. For instance, you might explain that your review includes only peer-reviewed [i.e., scholarly] sources.
• Standards : Description of the way in which you present your information.
• Questions for Further Research : What questions about the field has the review sparked? How will you further your research as a result of the review?

IV.  Writing Your Literature Review

Once you've settled on how to organize your literature review, you're ready to write each section. When writing your review, keep in mind these issues.

Use Evidence A literature review section is, in this sense, just like any other academic research paper. Your interpretation of the available sources must be backed up with evidence [citations] that demonstrates that what you are saying is valid. Be Selective Select only the most important points in each source to highlight in the review. The type of information you choose to mention should relate directly to the research problem, whether it is thematic, methodological, or chronological. Related items that provide additional information, but that are not key to understanding the research problem, can be included in a list of further readings . Use Quotes Sparingly Some short quotes are appropriate if you want to emphasize a point, or if what an author stated cannot be easily paraphrased. Sometimes you may need to quote certain terminology that was coined by the author, is not common knowledge, or taken directly from the study. Do not use extensive quotes as a substitute for using your own words in reviewing the literature. Summarize and Synthesize Remember to summarize and synthesize your sources within each thematic paragraph as well as throughout the review. Recapitulate important features of a research study, but then synthesize it by rephrasing the study's significance and relating it to your own work and the work of others. Keep Your Own Voice While the literature review presents others' ideas, your voice [the writer's] should remain front and center. For example, weave references to other sources into what you are writing but maintain your own voice by starting and ending the paragraph with your own ideas and wording. Use Caution When Paraphrasing When paraphrasing a source that is not your own, be sure to represent the author's information or opinions accurately and in your own words. Even when paraphrasing an author’s work, you still must provide a citation to that work.

V.  Common Mistakes to Avoid

These are the most common mistakes made in reviewing social science research literature.

• Sources in your literature review do not clearly relate to the research problem;
• You do not take sufficient time to define and identify the most relevant sources to use in the literature review related to the research problem;
• Relies exclusively on secondary analytical sources rather than including relevant primary research studies or data;
• Uncritically accepts another researcher's findings and interpretations as valid, rather than examining critically all aspects of the research design and analysis;
• Does not describe the search procedures that were used in identifying the literature to review;
• Reports isolated statistical results rather than synthesizing them in chi-squared or meta-analytic methods; and,
• Only includes research that validates assumptions and does not consider contrary findings and alternative interpretations found in the literature.

Cook, Kathleen E. and Elise Murowchick. “Do Literature Review Skills Transfer from One Course to Another?” Psychology Learning and Teaching 13 (March 2014): 3-11; Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Jesson, Jill. Doing Your Literature Review: Traditional and Systematic Techniques . London: SAGE, 2011; Literature Review Handout. Online Writing Center. Liberty University; Literature Reviews. The Writing Center. University of North Carolina; Onwuegbuzie, Anthony J. and Rebecca Frels. Seven Steps to a Comprehensive Literature Review: A Multimodal and Cultural Approach . Los Angeles, CA: SAGE, 2016; Ridley, Diana. The Literature Review: A Step-by-Step Guide for Students . 2nd ed. Los Angeles, CA: SAGE, 2012; Randolph, Justus J. “A Guide to Writing the Dissertation Literature Review." Practical Assessment, Research, and Evaluation. vol. 14, June 2009; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016; Taylor, Dena. The Literature Review: A Few Tips On Conducting It. University College Writing Centre. University of Toronto; Writing a Literature Review. Academic Skills Centre. University of Canberra.

Writing Tip

Break Out of Your Disciplinary Box!

Thinking interdisciplinarily about a research problem can be a rewarding exercise in applying new ideas, theories, or concepts to an old problem. For example, what might cultural anthropologists say about the continuing conflict in the Middle East? In what ways might geographers view the need for better distribution of social service agencies in large cities than how social workers might study the issue? You don’t want to substitute a thorough review of core research literature in your discipline for studies conducted in other fields of study. However, particularly in the social sciences, thinking about research problems from multiple vectors is a key strategy for finding new solutions to a problem or gaining a new perspective. Consult with a librarian about identifying research databases in other disciplines; almost every field of study has at least one comprehensive database devoted to indexing its research literature.

Frodeman, Robert. The Oxford Handbook of Interdisciplinarity . New York: Oxford University Press, 2010.

Another Writing Tip

Don't Just Review for Content!

While conducting a review of the literature, maximize the time you devote to writing this part of your paper by thinking broadly about what you should be looking for and evaluating. Review not just what scholars are saying, but how are they saying it. Some questions to ask:

• How are they organizing their ideas?
• What methods have they used to study the problem?
• What theories have been used to explain, predict, or understand their research problem?
• What sources have they cited to support their conclusions?
• How have they used non-textual elements [e.g., charts, graphs, figures, etc.] to illustrate key points?

When you begin to write your literature review section, you'll be glad you dug deeper into how the research was designed and constructed because it establishes a means for developing more substantial analysis and interpretation of the research problem.

Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1 998.

Yet Another Writing Tip

When Do I Know I Can Stop Looking and Move On?

Here are several strategies you can utilize to assess whether you've thoroughly reviewed the literature:

• Look for repeating patterns in the research findings . If the same thing is being said, just by different people, then this likely demonstrates that the research problem has hit a conceptual dead end. At this point consider: Does your study extend current research?  Does it forge a new path? Or, does is merely add more of the same thing being said?
• Look at sources the authors cite to in their work . If you begin to see the same researchers cited again and again, then this is often an indication that no new ideas have been generated to address the research problem.
• Search Google Scholar to identify who has subsequently cited leading scholars already identified in your literature review [see next sub-tab]. This is called citation tracking and there are a number of sources that can help you identify who has cited whom, particularly scholars from outside of your discipline. Here again, if the same authors are being cited again and again, this may indicate no new literature has been written on the topic.

Onwuegbuzie, Anthony J. and Rebecca Frels. Seven Steps to a Comprehensive Literature Review: A Multimodal and Cultural Approach . Los Angeles, CA: Sage, 2016; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016.

• << Previous: Theoretical Framework
• Next: Citation Tracking >>
• Last Updated: May 6, 2024 9:06 AM
• URL: https://libguides.usc.edu/writingguide

Evidence-Based Practice (EBP)

• The EBP Process
• Forming a Clinical Question
• Inclusion & Exclusion Criteria
• Acquiring Evidence
• Appraising the Quality of the Evidence
• Writing a Literature Review
• Finding Psychological Tests & Assessment Instruments

What Is a Literature Review?

A literature review is an integrated analysis of scholarly writings that are related directly to your research question. Put simply, it's  a critical evaluation of what's already been written on a particular topic . It represents the literature that provides background information on your topic and shows a connection between those writings and your research question.

A literature review may be a stand-alone work or the introduction to a larger research paper, depending on the assignment. Rely heavily on the guidelines your instructor has given you.

What a Literature Review Is Not:

• A list or summary of sources
• An annotated bibliography
• A grouping of broad, unrelated sources
• A compilation of everything that has been written on a particular topic
• Literary criticism (think English) or a book review

Why Literature Reviews Are Important

• They explain the background of research on a topic
• They demonstrate why a topic is significant to a subject area
• They discover relationships between research studies/ideas
• They identify major themes, concepts, and researchers on a topic
• They identify critical gaps and points of disagreement
• They discuss further research questions that logically come out of the previous studies

To Learn More about Conducting and Writing a Lit Review . . .

Monash University (in Australia) has created several extremely helpful, interactive tutorials. 

• The Stand-Alone Literature Review, https://www.monash.edu/rlo/assignment-samples/science/stand-alone-literature-review
• Researching for Your Literature Review,  https://guides.lib.monash.edu/researching-for-your-literature-review/home
• Writing a Literature Review,  https://www.monash.edu/rlo/graduate-research-writing/write-the-thesis/writing-a-literature-review

Keep Track of Your Sources!

A citation manager can be helpful way to work with large numbers of citations. See UMSL Libraries' Citing Sources guide for more information. Personally, I highly recommend Zotero —it's free, easy to use, and versatile. If you need help getting started with Zotero or one of the other citation managers, please contact a librarian.

• << Previous: Appraising the Quality of the Evidence
• Next: Finding Psychological Tests & Assessment Instruments >>
• Last Updated: Nov 15, 2023 11:47 AM
• URL: https://libguides.umsl.edu/ebp

Log in using your username and password

• Search More Search for this keyword Advanced search
• Latest content
• Current issue
• Write for Us
• BMJ Journals More You are viewing from: Google Indexer

You are here

• Volume 19, Issue 1
• Reviewing the literature
• Article Text
• Article info
• Citation Tools
• Rapid Responses
• Article metrics

• Joanna Smith 1 ,
• Helen Noble 2
• 1 School of Healthcare, University of Leeds , Leeds , UK
• 2 School of Nursing and Midwifery, Queens's University Belfast , Belfast , UK
• Correspondence to Dr Joanna Smith , School of Healthcare, University of Leeds, Leeds LS2 9JT, UK; j.e.smith1{at}leeds.ac.uk

https://doi.org/10.1136/eb-2015-102252

Statistics from Altmetric.com

Request permissions.

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

Implementing evidence into practice requires nurses to identify, critically appraise and synthesise research. This may require a comprehensive literature review: this article aims to outline the approaches and stages required and provides a working example of a published review.

Are there different approaches to undertaking a literature review?

What stages are required to undertake a literature review.

The rationale for the review should be established; consider why the review is important and relevant to patient care/safety or service delivery. For example, Noble et al 's 4 review sought to understand and make recommendations for practice and research in relation to dialysis refusal and withdrawal in patients with end-stage renal disease, an area of care previously poorly described. If appropriate, highlight relevant policies and theoretical perspectives that might guide the review. Once the key issues related to the topic, including the challenges encountered in clinical practice, have been identified formulate a clear question, and/or develop an aim and specific objectives. The type of review undertaken is influenced by the purpose of the review and resources available. However, the stages or methods used to undertake a review are similar across approaches and include:

Formulating clear inclusion and exclusion criteria, for example, patient groups, ages, conditions/treatments, sources of evidence/research designs;

Justifying data bases and years searched, and whether strategies including hand searching of journals, conference proceedings and research not indexed in data bases (grey literature) will be undertaken;

Developing search terms, the PICU (P: patient, problem or population; I: intervention; C: comparison; O: outcome) framework is a useful guide when developing search terms;

Developing search skills (eg, understanding Boolean Operators, in particular the use of AND/OR) and knowledge of how data bases index topics (eg, MeSH headings). Working with a librarian experienced in undertaking health searches is invaluable when developing a search.

Once studies are selected, the quality of the research/evidence requires evaluation. Using a quality appraisal tool, such as the Critical Appraisal Skills Programme (CASP) tools, 5 results in a structured approach to assessing the rigour of studies being reviewed. 3 Approaches to data synthesis for quantitative studies may include a meta-analysis (statistical analysis of data from multiple studies of similar designs that have addressed the same question), or findings can be reported descriptively. 6 Methods applicable for synthesising qualitative studies include meta-ethnography (themes and concepts from different studies are explored and brought together using approaches similar to qualitative data analysis methods), narrative summary, thematic analysis and content analysis. 7 Table 1 outlines the stages undertaken for a published review that summarised research about parents’ experiences of living with a child with a long-term condition. 8

• View inline

An example of rapid evidence assessment review

In summary, the type of literature review depends on the review purpose. For the novice reviewer undertaking a review can be a daunting and complex process; by following the stages outlined and being systematic a robust review is achievable. The importance of literature reviews should not be underestimated—they help summarise and make sense of an increasingly vast body of research promoting best evidence-based practice.

• ↵ Centre for Reviews and Dissemination . Guidance for undertaking reviews in health care . 3rd edn . York : CRD, York University , 2009 .
• ↵ Canadian Best Practices Portal. http://cbpp-pcpe.phac-aspc.gc.ca/interventions/selected-systematic-review-sites / ( accessed 7.8.2015 ).
• Bridges J , et al
• ↵ Critical Appraisal Skills Programme (CASP). http://www.casp-uk.net / ( accessed 7.8.2015 ).
• Dixon-Woods M ,
• Shaw R , et al
• Agarwal S ,
• Jones D , et al
• Cheater F ,

Twitter Follow Joanna Smith at @josmith175

Competing interests None declared.

Read the full text or download the PDF:

A Literature Review of Current Practices to Evaluate the Usability of External Human Machine Interface

• Conference paper
• First Online: 09 July 2023
• Cite this conference paper

• Yahua Zheng 9 , 10 ,
• Kangrui Wu 9 , 10 ,
• Ruisi Shi 9 , 10 ,
• Xiaopeng Zhu 11 &
• Jingyu Zhang 9 , 10  

Part of the book series: Lecture Notes in Computer Science ((LNAI,volume 14018))

Included in the following conference series:

• International Conference on Human-Computer Interaction

830 Accesses

In traditional traffic environments, human drivers can communicate with other drivers, cyclists, and pedestrians through gestures, facial expressions, etc., to convey their intentions. However, most of the current autonomous vehicles cannot effectively communicate with other road users with an autonomous driving model. The critical problem is that other road users need help understanding the intention of the autonomous vehicle. Thus, autonomous vehicles need to communicate with the outside world in addition to the ability to detect other road users and make relevant maneuvers to avoid potential conflicts. The external human-machine interface (eHMI) communicates with other road users outside the vehicle. It is believed to effectively resolve the conflict between fully autonomous vehicles and other road users. As pedestrians need to understand the intentions of the vehicles quickly and accurately, usability is of great importance for an eHMI. The current study sought to thoroughly analyze the existing literature on evaluation methods and establish a theory-driven evaluation system. We developed our evaluative framework based on the Situational Awareness model of pedestrians. In making a safe crossing decision, the pedestrians need to form a correct situation awareness in which they must form accurate perception, proper understanding, and timely prediction of vehicle behaviors [ 1 – 3 ]. Based on this model, a well-designed eHMI must facilitate the perception, understanding, and prediction processes. In this way, safety, perceptibility, intelligibility, and adaptability are required, and the four major usability domains have been theoretically established.

This is a preview of subscription content, log in via an institution to check access.

Access this chapter

• Available as PDF
• Read on any device
• Instant download
• Own it forever
• Available as EPUB and PDF
• Compact, lightweight edition
• Dispatched in 3 to 5 business days
• Free shipping worldwide - see info

Tax calculation will be finalised at checkout

Purchases are for personal use only

Institutional subscriptions

Endsley, M.R.: Measurement of situation awareness in dynamic systems. Hum Factors. 37 , 65–84 (1995). https://doi.org/10.1518/001872095779049499

Article   Google Scholar  

Palmeiro, A.R., van der Kint, S., Vissers, L., Farah, H., de Winter, J.C.F., Hagenzieker, M.: Interaction between pedestrians and automated vehicles: a wizard of Oz experiment. Transp. Res. Part F: Traffic Psychol. Behav. 58 , 1005–1020 (2018). https://doi.org/10.1016/j.trf.2018.07.020

Chen, W., Jiang, Q., Zhuang, X., Ma, G.: Comparison of pedestrians’ gap acceptance behavior towards automated and human-driven vehicles. In: Harris, D., Li, W.-C. (eds.) Engineering Psychology and Cognitive Ergonomics. Cognition and Design. LNCS (LNAI), vol. 12187, pp. 253–261. Springer, Cham (2020). https://doi.org/10.1007/978-3-030-49183-3_20

Chapter   Google Scholar  

de Clercq, K., Dietrich, A., NúñezVelasco, J.P., de Winter, J., Happee, R.: External human-machine interfaces on automated vehicles: effects on pedestrian crossing decisions. Hum Factors. 61 , 1353–1370 (2019). https://doi.org/10.1177/0018720819836343

Lanzer, M., et al.: Designing communication strategies of autonomous vehicles with pedestrians: an intercultural study. In: 12th International Conference on Automotive User Interfaces and Interactive Vehicular Applications. pp. 122–131. Association for Computing Machinery, New York, NY, USA (2020). https://doi.org/10.1145/3409120.3410653

Lee, Y.M., et al.: Investigating Pedestrians’ Crossing Behaviour During Car Deceleration Using Wireless Head Mounted Display: An Application Towards the Evaluation of eHMI of Automated Vehicles. https://drivingassessment.uiowa.edu/proceedings . Accessed 21 Mar 2022

Locken, A., Wintersberger, P., Frison, A.-K., Riener, A.: Investigating user requirements for communication between automated vehicles and vulnerable road users. In: 2019 IEEE Intelligent Vehicles Symposium (IV). pp. 879–884. IEEE, Paris, France (2019). https://doi.org/10.1109/IVS.2019.8814027

Eisma, Y.B., van Bergen, S., ter Brake, S.M., Hensen, M.T.T., Tempelaar, W.J., de Winter, J.C.F.: External human–machine interfaces: the effect of display location on crossing intentions and eye movements. Information 11 (1), 13 (2019). https://doi.org/10.3390/info11010013

de Visser, E.J., Pak, R., Shaw, T.H.: From ‘automation’ to ‘autonomy’: the importance of trust repair in human–machine interaction. Ergonomics 61 , 1409–1427 (2018). https://doi.org/10.1080/00140139.2018.1457725

Hagenzieker, M.P., van der Kint, S., Vissers, L., van Schagen, I.N.L.G.: Interactions between cyclists and automated vehicles: Results of a photo experiment. J. Transp. Saf. Secur. (2019)

Google Scholar  

Deb, S., Strawderman, L., Carruth, D.W., DuBien, J., Smith, B., Garrison, T.M.: Development and validation of a questionnaire to assess pedestrian receptivity toward fully autonomous vehicles. Transp. Res. Part C: Emerg. Technol. 84 , 178–195 (2017). https://doi.org/10.1016/j.trc.2017.08.029

Ackermans, S., Dey, D., Ruijten, P., Cuijpers, R.H., Pfleging, B.: The Effects of Explicit Intention Communication, Conspicuous Sensors, and Pedestrian Attitude in Interactions with Automated Vehicles. In: Proceedings of the 2020 CHI Conference on Human Factors in Computing Systems, pp. 1–14. Association for Computing Machinery, New York, NY, USA (2020). https://doi.org/10.1145/3313831.3376197

Eisma, Y.B., Reiff, A., Kooijman, L., Dodou, D., de Winter, J.C.F.: External human-machine interfaces: effects of message perspective. Transp. Res. Part F: Traffic Psychol. Behav. 78 , 30–41 (2021). https://doi.org/10.1016/j.trf.2021.01.013

Endsley, M.R.: Design and evaluation for situation awareness enhancement. Proc. Human Factors Soc. Ann. Meet. 32 , 97–101 (1988). https://doi.org/10.1177/154193128803200221

Jones, D.G., Endsley, M.R.: Sources of situation awareness errors in aviation. Aviat. Space Environ. Med. 67 , 507–512 (1996)

Endsley, M.R.: Situation models: an avenue to the modeling of mental models. Proc. Human Factors Ergon. Soc. Ann. Meet. 44 , 61–64 (2000). https://doi.org/10.1177/154193120004400117

Ackermann, C., Beggiato, M., Bluhm, L.-F., Löw, A., Krems, J.F.: Deceleration parameters and their applicability as informal communication signal between pedestrians and automated vehicles. Transport. Res. F: Traffic Psychol. Behav. 62 , 757–768 (2019). https://doi.org/10.1016/j.trf.2019.03.006

Bazilinskyy, P., Dodou, D., de Winter, J.: Survey on eHMI concepts: The effect of text, color, and perspective. Transp. Res. Part F: Traffic Psychol. Behav. 67 , 175–194 (2019). https://doi.org/10.1016/j.trf.2019.10.013

Lagström, T., Lundgren, V.M.: An investigation of pedestrian-driver communication and development of a vehicle external interface. Human Factors

Chen, K.-T., Chen, H.-Y.W.: Manipulating music to communicate automation reliability in conditionally automated driving: A driving simulator study. Int. J. Human-Comput. Stud. 145 , 102518 (2021). https://doi.org/10.1016/j.ijhcs.2020.102518

Othersen, I., Conti-Kufner, A.S., Dietrich, A., Maruhn, P., Bengler, K.: Designing for Automated Vehicle and Pedestrian Communication: Perspectives on eHMIs from Older and Younger Persons

Joisten, P., et al.: Displaying vehicle driving mode – effects on pedestrian behavior and perceived safety. In: Ahram, T., Karwowski, W., Pickl, S., Taiar, R. (eds.) Human Systems Engineering and Design II. AISC, vol. 1026, pp. 250–256. Springer, Cham (2020). https://doi.org/10.1007/978-3-030-27928-8_38

Zhuang, X., Wu, C.: The safety margin and perceived safety of pedestrians at unmarked roadway. Transport. Res. F Traffic Psychol. Behav. 15 , 119–131 (2012). https://doi.org/10.1016/j.trf.2011.11.005

Petzoldt, T.: On the relationship between pedestrian gap acceptance and time to arrival estimates. Accid. Anal. Prev. 72 , 127–133 (2014). https://doi.org/10.1016/j.aap.2014.06.019

Lobjois, R., Cavallo, V.: Age-related differences in street-crossing decisions: the effects of vehicle speed and time constraints on gap selection in an estimation task. Accid. Anal. Prev. 39 , 934–943 (2007). https://doi.org/10.1016/j.aap.2006.12.013

Chung, Y.-S., Chang, C.-Y.: Farther and safer: an illusion engendered by incapability? Transport. Res. F: Traffic Psychol. Behav. 54 , 110–123 (2018). https://doi.org/10.1016/j.trf.2018.01.020

Faas, S.M., Stange, V., Baumann, M.: Self-driving vehicles and pedestrian interaction: does an external human-machine interface mitigate the threat of a tinted windshield or a distracted driver? Int. J. Human–Comput. Interact. 37 (14), 1364–1374 (2021). https://doi.org/10.1080/10447318.2021.1886483

Osswald, S., Wurhofer, D., Trösterer, S., Beck, E., Tscheligi, M.: Predicting information technology usage in the car: towards a car technology acceptance model. In: Proceedings of the 4th International Conference on Automotive User Interfaces and Interactive Vehicular Applications, pp. 51–58. Association for Computing Machinery, New York, NY, USA (2012). https://doi.org/10.1145/2390256.2390264

Löcken, A., Golling, C., Riener, A.: How should automated vehicles interact with pedestrians? A comparative analysis of interaction concepts in virtual reality. In: Proceedings of the 11th International Conference on Automotive User Interfaces and Interactive Vehicular Applications, pp. 262–274. Association for Computing Machinery, New York, NY, USA (2019). https://doi.org/10.1145/3342197.3344544

Bazilinskyy, P., Kooijman, L., Dodou, D., De Winter, J.C.F.: How should external human-machine interfaces behave? Examining the effects of colour, position, message, activation distance, vehicle yielding, and visual distraction among 1,434 participants. Appl. Ergon. 95 , 103450 (2021). https://doi.org/10.1016/j.apergo.2021.103450

Forke, J., et al.: Understanding the Headless Rider: Display-Based Awareness and Intent-Communication in Automated Vehicle-Pedestrian Interaction in Mixed Traffic. Multimodal Technol. Interact. 5 , 51 (2021). https://doi.org/10.3390/mti5090051

Kaleefathullah, A.A., Merat, N., Lee, Y.M., Eisma, Y.B., Madigan, R., Garcia, J., de Winter, J.: External human–machine interfaces can be misleading: an examination of trust development and misuse in a CAVE-based pedestrian simulation environment. Human Factors: J. Human Factors Ergon. Soc. 64 (6), 1070–1085 (2020). https://doi.org/10.1177/0018720820970751

Witmer, B.G., Singer, M.J.: Measuring Presence in Virtual Environments: A Presence Questionnaire. Presence Teleop. Virt. 7 (3), 225–240 (1998). https://doi.org/10.1162/105474698565686

Faas, S.M., Mathis, L.-A., Baumann, M.: External HMI for self-driving vehicles: Which information shall be displayed? Transportation research. Part F, Traffic psychology and behaviour. 68 , 171–186 (2020). https://doi.org/10.1016/j.trf.2019.12.009

Bartneck, C., Kulić, D., Croft, E., Zoghbi, S.: Measurement Instruments for the Anthropomorphism, Animacy, Likeability, Perceived Intelligence, and Perceived Safety of Robots. Int J of Soc Robotics. 1 , 71–81 (2009). https://doi.org/10.1007/s12369-008-0001-3

Inoue, K., Nonaka, S., Ujiie, Y., Takubo, T., Arai, T.: Comparison of human psychology for real and virtual mobile manipulators. In: ROMAN 2005. IEEE International Workshop on Robot and Human Interactive Communication, pp. 73–78 (2005). https://doi.org/10.1109/ROMAN.2005.1513759

Kooijman, L., Happee, R., de Winter, J.: How do eHMIs affect pedestrians’ crossing behavior? A study using a head-mounted display combined with a motion suit. Information 10 (12), 386 (2019). https://doi.org/10.3390/info10120386

Roether, C.L., Omlor, L., Christensen, A., Giese, M.A.: Critical features for the perception of emotion from gait. J. Vis. 9 , 15 (2009). https://doi.org/10.1167/9.6.15

Crane, E., Gross, M.: Motion capture and emotion: affect detection in whole body movement. In: Paiva, A.C.R., Prada, R., Picard, R.W. (eds.) Affective Computing and Intelligent Interaction. LNCS, vol. 4738, pp. 95–101. Springer, Heidelberg (2007). https://doi.org/10.1007/978-3-540-74889-2_9

Rettenmaier, M., Schulze, J., Bengler, K.: How much space is required? Effect of distance, content, and color on external human–machine interface size. Information 11 (7), 346 (2020). https://doi.org/10.3390/info11070346

Bhagavathula, R., Williams, B., Owens, J., Gibbons, R.: The reality of virtual reality: a comparison of pedestrian behavior in real and virtual environments. Proc. Human Factors Ergon. Soc. Ann. Meet. 62 , 2056–2060 (2018). https://doi.org/10.1177/1541931218621464

Faas, S.M., Baumann, M.: Light-based external human machine interface: color evaluation for self-driving vehicle and pedestrian interaction. Proc. Human Factors Ergon. Soc. Ann. Meet. 63 , 1232–1236 (2019). https://doi.org/10.1177/1071181319631049

Sun, R., Zhuang, X., Wu, C., Zhao, G., Zhang, K.: The estimation of vehicle speed and stopping distance by pedestrians crossing streets in a naturalistic traffic environment. Transport. Res. F: Traffic Psychol. Behav. 30 , 97–106 (2015). https://doi.org/10.1016/j.trf.2015.02.002

Champion, R.A., Warren, P.A.: Contrast effects on speed perception for linear and radial motion. Vision. Res. 140 , 66–72 (2017). https://doi.org/10.1016/j.visres.2017.07.013

Hussain, Q., Alhajyaseen, W.K.M., Pirdavani, A., Reinolsmann, N., Brijs, K., Brijs, T.: Speed perception and actual speed in a driving simulator and real-world: a validation study. Transport. Res. F: Traffic Psychol. Behav. 62 , 637–650 (2019). https://doi.org/10.1016/j.trf.2019.02.019

Li, J., Guo, H., Pan, S., Tan, H.: Where is the best autonomous vehicle interactive display place when meeting a manual driving vehicle in intersection? In: Rau, P.-L. (ed.) Cross-Cultural Design. Applications in Cultural Heritage, Tourism, Autonomous Vehicles, and Intelligent Agents. LNCS, vol. 12773, pp. 225–239. Springer, Cham (2021). https://doi.org/10.1007/978-3-030-77080-8_19

Oudshoorn, M., de Winter, J., Bazilinskyy, P., Dodou, D.: Bio-inspired intent communication for automated vehicles. Transport. Res. F: Traffic Psychol. Behav. 80 , 127–140 (2021). https://doi.org/10.1016/j.trf.2021.03.021

She, J., Islam, M., Zhou, F.: The Effect of Dynamic Speed Information and Timing of Displaying EHMI on Automated Vehicle and Pedestrian Interactions. In: ASME 2021 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference November 17 (2021). https://doi.org/10.1115/DETC2021-68319

Eisma, Y.B., Cabrall, C.D.D., de Winter, J.C.F.: Visual sampling processes revisited: replicating and extending senders (1983) using modern eye-tracking equipment. IEEE Trans. Human-Mach. Syst. 48 , 526–540 (2018). https://doi.org/10.1109/THMS.2018.2806200

Feldstein, I.T.: Impending collision judgment from an egocentric perspective in real and virtual environments: a review. Perception 48 , 769–795 (2019). https://doi.org/10.1177/0301006619861892

Dey, D., et al.: Distance-dependent eHMIs for the interaction between automated vehicles and pedestrians. In: 12th International Conference on Automotive User Interfaces and Interactive Vehicular Applications, pp. 192–204. Association for Computing Machinery, New York, NY, USA (2020). https://doi.org/10.1145/3409120.3410642

Faas, S.M., Kao, A.C., Baumann, M.: a longitudinal video study on communicating status and intent for self-driving vehicle-pedestrian interaction. In: Proceedings of the 2020 CHI Conference on Human Factors in Computing Systems, pp. 1–14. Association for Computing Machinery, New York, NY, USA (2020). https://doi.org/10.1145/3313831.3376484

Holländer, K., Krüger, A., Butz, A.: Save the smombies: app-assisted street crossing. In: 22nd International Conference on Human-Computer Interaction with Mobile Devices and Services, pp. 1–11. Association for Computing Machinery, New York, NY, USA (2020). https://doi.org/10.1145/3379503.3403547

She, J., Neuhoff, J., Yuan, Q.: Shaping pedestrians’ trust in autonomous vehicles: an effect of communication style, speed information, and adaptive strategy. J. Mech. Des. 143 (2021). https://doi.org/10.1115/1.4049866

Dey, D., Matviienko, A., Berger, M., Pfleging, B., Martens, M., Terken, J.: Communicating the intention of an automated vehicle to pedestrians: the contributions of eHMI and vehicle behavior it. Inf. Technol. 63 (2), 123–141 (2020). https://doi.org/10.1515/itit-2020-0025

Şahin, H., Vöge, S., Stahr, B., Trilck, N., Boll, S.: An exploration of potential factors influencing trust in automated vehicles. In: Ardito, C., et al. (eds.) Human-Computer Interaction – INTERACT 2021. LNCS, vol. 12936, pp. 364–367. Springer, Cham (2021). https://doi.org/10.1007/978-3-030-85607-6_38

Li, Y., Dikmen, M., Hussein, T.G., Wang, Y., Burns, C.: To cross or not to cross: urgency-based external warning displays on autonomous vehicles to improve pedestrian crossing safety. In: Proceedings of the 10th International Conference on Automotive User Interfaces and Interactive Vehicular Applications, pp. 188–197. Association for Computing Machinery, New York, NY, USA (2018). https://doi.org/10.1145/3239060.3239082

Rettenmaier, M., Albers, D., Bengler, K.: After you?! – Use of external human-machine interfaces in road bottleneck scenarios. Transport. Res. F: Traffic Psychol. Behav. 70 , 175–190 (2020). https://doi.org/10.1016/j.trf.2020.03.004

Colley, M., Mytilineos, S.C., Walch, M., Gugenheimer, J., Rukzio, E.: Evaluating highly automated trucks as signaling lights. In: 12th International Conference on Automotive User Interfaces and Interactive Vehicular Applications, pp. 111–121. Association for Computing Machinery, New York, NY, USA (2020). https://doi.org/10.1145/3409120.3410647

Schlackl, D., Weigl, K., Riener, A.: eHMI visualization on the entire car body: results of a comparative evaluation of concepts for the communication between AVs and manual drivers. In: Proceedings of the Conference on Mensch und Computer, pp. 79–83. Association for Computing Machinery, New York, NY, USA (2020). https://doi.org/10.1145/3404983.3410011

Wintersberger, P., von Sawitzky, T., Frison, A.-K., Riener, A.: Traffic augmentation as a means to increase trust in automated driving systems. In: Proceedings of the 12th Biannual Conference on Italian SIGCHI Chapter, pp. 1–7. Association for Computing Machinery, New York, NY, USA (2017). https://doi.org/10.1145/3125571.3125600

Verstegen, R., Dey, D., Pfleging, B.: CommDisk: a holistic 360°; eHMI concept to facilitate scalable, unambiguous interactions between automated vehicles and other road users. In: 13th International Conference on Automotive User Interfaces and Interactive Vehicular Applications, pp. 132–136. Association for Computing Machinery, New York, NY, USA (2021). https://doi.org/10.1145/3473682.3480280

Clamann, M., Aubert, M., Cummings, M.L.: Evaluation of vehicle-to-pedestrian communication displays for autonomous vehicles. In: Transportation Research Board 96th Annual MeetingTransportation Research Board (2017)

Download references

Author information

Authors and affiliations.

CAS. Key Laboratory of Behavioral Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, China

Yahua Zheng, Kangrui Wu, Ruisi Shi & Jingyu Zhang

Department of Psychology, University of the Chinese Academy of Sciences, Beijing, China

Chongqing Changan Automobile Co., Ltd., Chongqing, China

Xiaopeng Zhu

You can also search for this author in PubMed   Google Scholar

Corresponding author

Correspondence to Jingyu Zhang .

Editor information

Editors and affiliations.

Coventry University, Coventry, UK

Cranfield University, Cranfield, UK

Wen-Chin Li

Rights and permissions

Reprints and permissions

Copyright information

© 2023 The Author(s), under exclusive license to Springer Nature Switzerland AG

About this paper

Cite this paper.

Zheng, Y., Wu, K., Shi, R., Zhu, X., Zhang, J. (2023). A Literature Review of Current Practices to Evaluate the Usability of External Human Machine Interface. In: Harris, D., Li, WC. (eds) Engineering Psychology and Cognitive Ergonomics. HCII 2023. Lecture Notes in Computer Science(), vol 14018. Springer, Cham. https://doi.org/10.1007/978-3-031-35389-5_40

Download citation

DOI : https://doi.org/10.1007/978-3-031-35389-5_40

Published : 09 July 2023

Publisher Name : Springer, Cham

Print ISBN : 978-3-031-35388-8

Online ISBN : 978-3-031-35389-5

eBook Packages : Computer Science Computer Science (R0)

Share this paper

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

• Publish with us

Policies and ethics

• Find a journal
• Track your research

An analysis of current practices in undertaking literature reviews in nursing: findings from a focused mapping review and synthesis

Affiliations.

• 1 Faculty of Health and Life Sciences, Oxford Brookes University, Jack Straw's Lane, Oxford, OX3 0FL, England, UK. [email protected].
• 2 University of Birmingham, Birmingham, England, UK.
• PMID: 31096917
• PMCID: PMC6524227
• DOI: 10.1186/s12874-019-0751-7

Background: In this paper we discuss the emergence of many different methods for doing a literature review. Referring back to the early days, when there were essentially two types of review; a Cochrane systematic review and a narrative review, we identify how the term systematic review is now widely used to describe a variety of review types and how the number of available methods for doing a literature review has increased dramatically. This led us to undertake a review of current practice of those doing a literature review and the terms used to describe them.

Method: We undertook a focused mapping review and synthesis. Literature reviews; defined as papers with the terms review or synthesis in the title, published in five nursing journals between January 2017-June 2018 were identified. We recorded the type of review and how these were undertaken.

Results: We identified more than 35 terms used to describe a literature review. Some terms reflected established methods for doing a review whilst others could not be traced to established methods and/or the description of method in the paper was limited. We also found inconsistency in how the terms were used.

Conclusion: We have identified a proliferation of terms used to describe doing a literature review; although it is not clear how many distinct methods are being used. Our review indicates a move from an era when the term narrative review was used to describe all 'non Cochrane' reviews; to a time of expansion when alternative systematic approaches were developed to enhance rigour of such narrative reviews; to the current situation in which these approaches have proliferated to the extent so that the academic discipline of doing a literature review has become muddled and confusing. We argue that an 'era of consolidation' is needed in which those undertaking reviews are explicit about the method used and ensure that their processes can be traced back to a well described, original primary source.

Keywords: Evidence synthesis; Literature review; Meta-ethnography; Systematic review.

• Nursing / methods*
• Review Literature as Topic*
• Systematic Reviews as Topic*

• Reference Manager
• Simple TEXT file

People also looked at

Policy and practice reviews article, the perks of being an organic chicken – animal welfare science on the key features of organic poultry production.

• Department of Applied Animal Science and Welfare, Swedish University of Agricultural Sciences (SLU), Skara, Sweden

Modern poultry production entails a number of important animal welfare issues. However, welfare is often considered to be better in organic than in non-organic production, largely due to the focus on naturalness within the former which has been embedded within the EU regulations on organic production. The aim of this paper was to review the relevant scientific literature to assess (i) how animal welfare science relates to the key features of organic poultry production which originally stem from organic visions and ideological reasons, and (ii) whether there is scientific evidence to show that these key features, as stipulated in current EU regulations, contribute to higher welfare in organic poultry production. We identified seven key features that are intended to improve poultry welfare in organic production: appropriate breeds, no mutilations, outdoor access, natural light, perch space and raised sitting levels, provision of roughage, and lower stocking densities. In general, the animal welfare science available supports the potential for higher animal welfare in organic poultry production, based on the requirements as laid down in the current EU regulations. However, there is still room for improvement, and some aspects that may further improve animal welfare in organic poultry production include the use of alternative laying hen hybrids with the potential for better welfare, even more slow-growing broilers, appropriate management of the free-range areas in practice to ensure that they are used by the birds, additional raised sitting level space allowance for broilers, and the use of “dark brooders” for chicks.

1 Introduction

The development of organic agriculture, which began in the first half of the 20 th century, was a response to the preceding intensification of agriculture ( Padel et al., 2004 ). It involved the convergence of a number of alternative agricultural movements based on the pursuit of a more natural way of living and a more sustainable way of farming ( Padel et al., 2004 ), a desire to preserve rural life, and the holistic conviction that healthy soils give healthy food, promoting human health ( Vaarst et al., 2004 ).

The organic vision is based on a holistic approach, and the concept of an integrated agricultural system where there is harmony between the land, the people and animals ( Vaarst et al., 2004 ). Initially, animals were primarily considered to be important as part of such an integrated agricultural system, but organic farming eventually also came to include concerns for the welfare of animals per se in intensive livestock production ( Padel et al., 2004 ). Good animal health and high animal welfare standards are thus inherent to organic agriculture; in particular, natural living and the ability to express natural behaviours in a natural environment is considered to be a prerequisite for good animal welfare ( Vaarst and Alrøe, 2012a ; IFOAM, 2024a ). Since organic production is based on an ecocentric view, natural living is considered to be valuable in itself ( Lund and Algers, 2003 ; Lund, 2006 ). Indeed, organic standards more explicitly focus on natural behaviours in comparison to other animal welfare regulations ( Lundmark et al., 2014 ).

In 1972, the International Federation of Organic Agriculture Movements (IFOAM) was founded to promote the organic movement worldwide ( IFOAM, 2024a ). This non-governmental umbrella organisation coordinates a global network of organic agriculture member organisations, and the IFOAM vision encompasses the world-wide adoption of an ecologically, socially and economically sound agricultural system in line with the four principles of organic agriculture – health, ecology, fairness and care ( IFOAM, 2024a ). Although not always explicitly stated, high animal welfare standards are embedded in each of these four principles of organic agriculture ( Vaarst and Alrøe, 2012a ). To harmonise the organic concept and what it encompasses, IFOAM has established internationally applicable basic standards for organic farming. Based on the four principles and the organic vision, these standards serve as guidance for organic organisations developing national standards ( Padel et al., 2004 ).

Organic production and marketing have been regulated in the EU since 1991, first including only crop production, with EU regulations on organic animal husbandry introduced in 1999. Since 2022, the EU requirements for organic animal production are set by Regulation (EU) 2018/848 of the European Parliament and of the Council of 30 May 2018 on organic production and labelling of organic products and repealing Council Regulation (EC) No 834/2007 (hereafter referred to as EU regulation 2018/848) and the Commission implementing regulation (EU) 2020/464 of 26 March 2020 laying down certain rules for the application of Regulation (EU) 2018/848 of the European Parliament and of the Council (hereafter referred to as EU regulation 2020/646). These provide a common legal framework within the EU, while also reflecting the IFOAM principles ( Padel et al., 2004 ). According to the first preamble in the EU regulation 2018/848: “Organic production is an overall system of farm management and food production that combines best environmental and climate action practices, a high level of biodiversity, the preservation of natural resources and the application of high animal welfare standards and high production standards in line with the demand of a growing number of consumers for products produced using natural substances and processes”.

The general objective of the current EU organic regulations in terms of improved animal welfare is to safeguard the species-specific behavioural needs of animals, and to ensure that husbandry practices, including stocking densities, housing conditions and choice of breeds, meet the animals’ developmental, physiological and ethological needs (EU regulation 2018/848). This entails, for example, outdoor access, lower stocking densities, and the use of appropriate breeds. To highlight some of the specific features intended to improve animal welfare in organic poultry production, the minimum requirements as laid down by the EU regulations on organic production are presented in Table 1 , alongside the minimum rules for the protection of laying hens and broiler chickens in conventional production, as stipulated in the Council Directive 1999/74/EC of 19 July 1999 laying down minimum standards for the protection of laying hens (hereafter referred to as directive 1999/74/EC) and the Council Directive 2007/43/EC of 28 June 2007 laying down minimum rules for the protection of chickens kept for meat production (hereafter referred to as directive 2007/43/EC).

Table 1 Minimum standards for the housing and management of laying hens (Directive 1999/74/EC) and broiler chickens (Directive 2007/43/EC) in conventional and organic (EU regulation 2018/848, EU regulation 2020/464) poultry production in the European Union.

Commercial poultry production encompasses a number of welfare problems, which are not limited to conventional production but can be found in organic poultry as well ( Åkerfeldt et al., 2021 ), such as keel bone fractures ( Thøfner et al., 2021 ) and severe feather pecking in laying hens ( Jung and Knierim, 2018 ), and impaired gait in broilers ( Göransson et al., 2020 ). Some might even argue that organic poultry production brings about welfare issues generally not found in non-organic systems, such as exposure to parasites, extreme weather conditions and predators in outdoor areas ( Holt, 2021 ).

Although the focus of this paper is on the EU regulations on organic production, it may nonetheless be of international relevance, since the content of the EU organic regulations is a reflection of the internationally applicable IFOAM Standards. Governmental and private organic standards that successfully pass an assessment against the IFOAM Standards are included in the “IFOAM Family of Standards” ( IFOAM, 2024b ). The EU organic regulations were included in 2013 (IFOAM 2024b), and as such they share common objectives and requirements with the other worldwide organic standards included in the IFOAM Family of Standards. Although the purpose of the IFOAM Standards is to harmonise the organic concept across countries, there is nonetheless room for adaptation to local ecological conditions, and there may thus be specific requirements that partly differ between various organic standards, also within the IFOAM Family of Standards ( Padel et al., 2004 ).

Organic production is based on a solid ideology with clear visions and principles, and the specific requirements stipulated in both private and governmental organic standards are not necessarily grounded solely on scientific evidence. Thus, the aim of this paper is to review relevant scientific literature to assess (i) how animal welfare science relates to the key features of organic poultry production which originally stems from organic visions and ideological reasons, and (ii) whether there is scientific evidence to show that these key features, as stipulated in current EU regulations, contribute to higher welfare in organic poultry production. The key features of organic poultry production included and outlined below are those directly linked to and intended to improve animal welfare.

2 Seven key features of organic poultry production to improve bird welfare

2.1 appropriate breeds.

The current EU regulations hold that the choice of breeds or strains should be “appropriate to the principles of organic production” and that preference should be given to those breeds or strains that, for example, have a high capacity to adapt to local conditions and that are not associated with specific diseases or health problems as seen in intensive production (EU regulation 2018/848).

For broilers, this means that slow-growing (as defined by the competent authority in each member state) hybrids should be used (EU regulation 2018/848). Numerous studies comparing broiler hybrids with different growth rates demonstrate that fast growth is associated with impaired mobility and lameness ( Dixon, 2020 ; Rayner et al., 2020 ; Baxter et al., 2021 ; Dawson et al., 2021 ). This constitutes a welfare issue not only due to the associated pain ( Caplen et al., 2013 ) but also because of difficulties in accessing resources such as perches ( Wallenbeck et al., 2016 ; Malchow et al., 2019 ; Baxter et al., 2021 ), and, as a result of inactivity and spending extended periods of time sitting down, the development of hock burns ( Dixon, 2020 ). Slow-growing broilers, on the other hand, are more active and display more play and exploratory behaviour in comparison with fast-growing hybrids ( Baxter et al., 2021 ; Dawson et al., 2021 ). The performance of such behaviours may be rewarding in themselves ( Mellor, 2015a ), but higher activity levels can also lead to better welfare through beneficial effects on skeletal development and leg health ( Güz et al., 2021 ). Slow-growing broilers have also been associated with a lower prevalence of foot pad dermatitis ( Kjaer et al., 2006 ; Sarica et al., 2014 ; Wilhelmsson et al., 2019 ), as well as lower mortality rates ( Rayner et al., 2020 ). Furthermore, it should be noted that the welfare benefits of using slow-growing hybrids extend to the broiler breeders, with reference to the welfare issues following severe feed restrictions ( EFSA, 2023a ).

The laying hen hybrids used on organic farms are commonly the same as those used in other commercial egg production systems. Amongst these, there are strain differences in terms of, for example, fearfulness and fear responses ( Nelson et al., 2020 ; Brown et al., 2022 ), immune function ( Hofmann et al., 2021 ; Schmucker et al., 2021 ), levels of feather pecking ( Brinker et al., 2014 ), susceptibility to keel bone damages ( Stratmann et al., 2016 ), behaviour, and resource use ( Ali et al., 2016 ), including use of outdoor areas ( Wurtz et al., 2022 ). By choosing one hybrid over another, some welfare benefits might thus be acquired. However, there is currently no breed considered to be a ‘higher welfare breed’ showing, for example, a particularly high resistance to disease, low levels of severe feather pecking or keel bone damages, and ample use of outdoor areas ( Fernyhough et al., 2020 ). Corresponding to the welfare issues associated with high growth rates in broilers, genetic selection for extraordinarily high levels of egg production and the early onset of lay has been linked to problems like keel bone fractures ( Thøfner et al., 2021 ), reduced immunocompetence ( Schmucker et al., 2021 ), and decreased engagement in social behaviour ( Dudde et al., 2018 ). Indeed, dual-purpose hens, which produce less and smaller eggs than commercial layer hybrids, appear to be less fearful ( Giersberg et al., 2020a ) and display significantly less severe feather pecking and cannibalism ( Giersberg et al., 2020b ; Rieke et al., 2021 ) than commercial laying hen hybrids.

In conclusion, the transition from fast-growing broilers to more slow-growing hybrids, on both organic and non-organic farms, has resulted in notable welfare improvements. Similarly, research findings suggest that selecting for lower egg production can alleviate certain welfare issues in laying hens. Although some of the currently used hybrids may be relatively better suited for organic egg production, the welfare benefits achieved through a well thought-through choice between these are, nevertheless, limited.

2.2 No mutilations (beak trimming prohibited)

Mutilations, such as beak trimming, is not allowed in organic production (although beak trimming may be undertaken during the first three days of life, but only as an exception) (EU regulation 2018/848).

While beak trimming is performed as a preventative strategy against severe feather pecking and cannibalism ( Glatz and Underwood, 2021 ), the process constitutes a welfare issue in itself, considering that the beak is highly innervated and very sensitive ( Gentle, 1989 ). The traditional hot blade (HB) technique involves a heated guillotine-type blade used to cut and cauterize the beak tissue of the upper and lower beak tip ( Glatz and Underwood, 2021 ). This method has been associated with acute pain and a reduction in beak-related behaviours ( Gentle et al., 1997 ; Marchant-Forde et al., 2008 ), as well as neuroma formation and evidence of chronic pain ( Lunam et al., 1996 ). It may also impair normal exploratory behaviour due to a loss of sensitivity and magnetoreception ( Freire et al., 2011 ). Infrared (IR) beak trimming, i.e. cutting the beak with infrared radiation so that the beak tip softens and falls off over subsequent days ( Glatz and Underwood, 2021 ), has largely replaced the HB method as the former seem to have less negative welfare consequences than the latter ( EFSA, 2023b ). Although some have suggested that IR treatment does not induce acute pain ( Gentle and McKeegan, 2007 ), other findings indicate that it might, since young chicks have been observed to be less active and to spend less time eating and drinking during the first days after the procedure compared to control chicks ( Marchant-Forde et al., 2008 ). Acute pain may arise especially if too much tissue is removed, e.g. due to poorly calibrated equipment ( Dennis and Cheng, 2012 ; Glatz and Underwood, 2021 ). The evidence for long-term pain following IR beak trimming is also inconsistent, since neuromas have been demonstrated in adult hens ( Glatz and Hinch, 2008 ), though not in more recent studies ( McKeegan and Philbey, 2012 ; Struthers et al., 2019 ). The details of how the IR procedure affects the beak tissue are not yet fully understood ( Struthers et al., 2019 ), and the formation of neuromas might depend, for example, on the level of beak treatment ( Glatz and Underwood, 2021 ).

In general, laying hen flocks with intact beaks show a higher prevalence of, and more severe, plumage damage compared to beak trimmed hens (e.g. Lambton et al., 2010 ; Sepeur et al., 2015 ; Riber and Hinrichsen, 2017 ; van Staaveren et al., 2021 ). Some studies also report higher mortality in non-trimmed flocks ( Lambton et al., 2013 ; Sepeur et al., 2015 ; Riber and Hinrichsen, 2017 ), although others have found no such association ( Schuck-Paim et al., 2021 ). Blunt beaks do not only result in less damage as a consequence of feather- or injurious pecking, but beak trimmed birds have also been seen to perform less of these behaviours ( Lambton et al., 2010 ; Schwarzer et al., 2021 ). However, these behaviours may also be evident in beak trimmed flocks ( Lambton et al., 2010 , 2013 ). Thus, it is important to emphasise that the mitigation of feather- and other types of injurious pecking also involves other important preventative strategies, including various housing and management practices such as providing high-quality foraging substrates ( EFSA, 2023b ).

In conclusion, beak trimming may induce pain and compromise the function of the beak as an important tool, e.g. for foraging. Nevertheless, infrared beak trimming is considered to be a more welfare-friendly alternative, in comparison with the hot blade technique. The potential welfare issues of the procedure must be weighed against the welfare issues associated with feather pecking and cannibalism. Although beak trimming may help mitigate these problems, it is not a solution that addresses the root cause(s) of feather pecking, nor does the procedure eliminate the behaviour or the resulting damage.

2.3 Outdoor access

Laying hens and broilers in organic production should have outdoor access during at least one third of their life, and whenever weather and seasonal conditions and the state of the ground allow, except for when temporary restrictions have been imposed due to, for example, outbreaks of aviary influenza (EU regulation 2018/848). Moreover, such open-air areas should be attractive to the birds and provide them with sufficient protection, such as shelters or trees (EU regulation 2020/464).

Individual broiler chickens that show relatively high levels of foraging behaviour have been shown to also use the free-range more, indicating that the increased foraging opportunities that the outdoor area offers are highly important ( Ferreira et al., 2022 ). Laying hens have been shown to prefer the free-range for the performance of foraging as well as dust bathing ( Campbell et al., 2017 ; Thuy Diep et al., 2018 ), especially the areas that provide protection and shade ( Larsen et al., 2017 ; De Koning et al., 2018 ). In laying hens, free-ranging appear to have a protective effect against severe feather pecking, likely due to the enhanced foraging opportunities, alongside a lowered indoor stocking density ( Lambton et al., 2010 ; Bestman and Wagenaar, 2014 ; Bestman et al., 2017 ). Moreover, providing an outdoor area enables the animals to make a choice between this and the indoor space. Such a choice allows the birds to exert some control over their environment, which may in itself be rewarding and improve animal welfare ( Leotti et al., 2010 ). Free-ranging has also been associated with, for example, better cardiovascular function and improved gait in broilers, of which the latter might be due to better muscle and bone strength following increased locomotion and activity levels ( Taylor et al., 2018 ). No such positive effect of free-ranging on skeletal bone quality has yet been demonstrated in laying hens ( Sibanda et al., 2020 ). Some results indicate that free-ranging may also contribute to improved foot health in broilers and laying hens ( Gouveia et al., 2009 ; Dal Bosco et al., 2014 ; Rodriguez-Aurrekoetxea and Estevez, 2016 ), whereas other findings suggest the opposite ( Pagazaurtundua and Warriss, 2006 ; Sarica et al., 2014 ; Grafl et al., 2017 ; Taylor et al., 2020 ). The effect of outdoor access on foot health in poultry is thus not completely clear, and probably depends largely on actual range use and ground conditions.

One major drawback of outdoor access that may compromise poultry welfare is the evident risk of predators, which has been reported as a major mortality cause in free-range systems ( Bestman and Bikker-Ouwejan, 2020 ; Göransson et al., 2020 ). Although the risk of predator attacks might be difficult to completely eliminate, especially from aerial predators, proper fencing and sufficient protective cover can nevertheless help reduce this welfare issue ( Van de Weerd et al., 2009 ; Göransson et al., 2021 ; Bonnefous et al., 2022 ). Another peril of free-ranging is that of infectious disease transmission, considering the biosecurity challenges associated with outdoor access ( Gonzales et al., 2017 ; Guinat et al., 2022 ). The introduction of, for example, highly pathogenic avian influenza (HPAI) virus may lead to widespread disease outbreaks, with severe health impairments, high mortality rates and mass culling of poultry flocks. Direct contact with infected wild birds in the free-range is an important and indisputable risk factor. However, the transmission of HPAI is epidemiologically complex and has also been shown to occur farm-to-farm due to human-mediated activities ( EFSA, 2017 ; Guinat et al., 2022 ). Due to the aforementioned biosecurity challenges and the difficulties of disinfecting an outdoor area, free-range systems may also leave poultry more exposed to gastrointestinal parasites ( Bonnefous et al., 2022 ). However, a number of studies indicate that free-ranging may not necessarily constitute a risk factor for endoparasitic infections, given that hens use and disperse well throughout the range ( Jansson et al., 2010 ; Sherwin et al., 2013 ; Thapa et al., 2015 ).

In conclusion, outdoor access can improve poultry welfare by providing greater opportunities to perform highly motivated behaviours, such as foraging and dust bathing, which may in addition reduce welfare issues such as severe feather pecking in laying hens. Moreover, free-ranging can also improve bird health. Outdoor access is not without welfare risks, such as predation and infectious disease transmission, though. However, appropriate management and design of the free-range area can, to a certain extent, combat and reduce these risks.

2.4 Natural light and eight-hour nocturnal rest period

In organic production, the birds must have a nocturnal rest period without artificial light of at least eight consecutive hours. Moreover, natural light inlets are required (EU regulation 2018/848).

One important component of ‘natural light’ is ultraviolet (UV) light. Poultry, in contrast to humans for example, have the capacity to perceive UVA wavelengths (315-400 nm) ( Prescott and Wathes, 1999b ). UV light is reflected in the chicken plumage, as well as certain foraging substrates, and thus lighting including this spectral characteristic might be imperative for foraging and normal social behaviours in poultry ( Prescott and Wathes, 1999a ; Maddocks et al., 2001 ). Not only do laying hens seem to prefer an environment containing UV light ( Wichman et al., 2021 ), but laying hens ( Sobotik et al., 2020 ) and broilers ( House et al., 2020 ) provided with it show lower stress and fear levels. Moreover, there is also some evidence indicating that UVB light (280–315 nm) exposure may have positive animal welfare consequences through improved skeletal health in both laying hens and broilers (see Rana and Campbell, 2021 for a review). Besides the UV wavelengths contained in natural light, the natural variations seen throughout the day in terms of colour and light intensity have been suggested to positively affect poultry behaviour and their circadian rhythm ( Prescott and Wathes, 1999b ). Increased activity levels have been observed in both laying hens ( Wichman et al., 2021 ) and fast-growing broilers provided with natural light ( Bailie et al., 2013 ; de Jong and Gunnink, 2019 ), with a reduced time spent lying down and resting in the latter, which might thus also indirectly contribute to improved leg health in broilers ( Bailie et al., 2013 ).

The general consensus is that continuous (i.e. artificial light on 24 h per day) or near-continuous lighting programmes should be avoided, and that providing broilers (on which the predominant amount of relevant research has been performed) with a longer (≥ 4 h) period of darkness contributes to improved welfare ( Bayram and Özkan, 2010 ; Schwean-Lardner et al., 2014 ; Sun et al., 2017 ). Four hours of darkness per day, at least, appears to allow for the development of a circadian rhythm and flock behavioural synchronisation ( Bayram and Özkan, 2010 ; Schwean-Lardner et al., 2014 ). However, a more pronounced effect was found when the dark period extended over seven or ten hours ( Schwean-Lardner et al., 2014 ). A clear circadian rhythm not only promotes the performance of more active behaviours during the light period but also allows for synchronised resting within the flock during the dark period, which helps prevent sleep disruption and, thus, sleep deprivation ( Schwean-Lardner et al., 2014 ). Longer periods of darkness (≥4 or ≥6 h) have been shown to positively affect the immune system status ( Hofmann et al., 2020 ), decrease mortality ( Schwean-Lardner et al., 2013 ), improve leg health and walking abilities ( Schwean-Lardner et al., 2013 ; Karaarslan and Nazlıgül, 2018 ), and reduce fearfulness ( Bayram and Özkan, 2010 ). Although lighting programmes with a clear day and night better enable the development of a circadian rhythm, the welfare implications of providing the dark period as one distinct period, rather than interrupting it (i.e. turning the lights on for a few hours), warrant further research ( EFSA, 2023a ). Turning the lights on during the dark period, as compared to providing the same number of uninterrupted dark hours, seems to stimulate a higher feed intake and thus increase body weight gain in fast-growing broilers ( Duve et al., 2011 ; Sun et al., 2017 ). Hence, an uninterrupted nocturnal period may indirectly have positive welfare consequences associated with a somewhat reduced growth rate. However, using an intermittent lighting scheme has recently been shown to increase broiler synchronisation and improve resting ( Forslind, 2023 ).

In conclusion, there is scientific evidence indicating that poultry welfare may be improved by providing a light environment similar to the one in which avian vision evolved. Although several constituents of natural light may be important, it is clear that the UV wavelengths contained in natural light are an essential component. Providing chickens with extended nocturnal (dark) periods has profound welfare benefits, as opposed to using continuous or near-continuous lighting programmes; no less than seven to eight hours without artificial lights is recommended for broilers ( EFSA, 2023a ). However, whether six, eight or ten hours of darkness is optimal from an animal welfare perspective, and whether an uninterrupted dark period or intermittent lighting programmes should be used, is not completely clear.

2.5 Perches and raised sitting levels

Laying hens in organic production must be provided with a minimum of 18 cm of perch per bird. For broilers, a minimum of 5 cm of perch or 25 cm 2 of raised sitting level per bird is required (EU regulation 2020/464).

Laying hens are highly motivated to perch, especially during the night-time, and the opportunity to do so is imperative for their welfare ( Olsson and Keeling, 2000 ). Riddle et al. (2018) showed that the horizontal space requirements while perching was, on average, around 18 cm and 22 cm in two white and two brown hybrids, respectively. However, in another study of a different brown hybrid, the body width while perching was found to be slightly less than 15 cm ( Giersberg et al., 2019 ). These authors have emphasised the importance of considering such hybrid differences when stipulating minimum standards ( Riddle et al., 2018 ; Giersberg et al., 2019 ). Others have concluded that providing 15 cm perch per bird (as required in conventional EU egg production) is insufficient if synchronised perching within a flock is to be ensured, suggesting that at least 18-20 cm per bird would better enable this ( Newberry et al., 2001 ; Savory et al., 2002 ; Cook et al., 2011 ). It has also been suggested that additional welfare benefits, regarding plumage condition and breast skin lesions, might come from increasing the perch space allowance further (up to 32.2 cm per bird) ( Steenfeldt and Nielsen, 2015b ). Laying hens show a clear preference for the top perches in multi-tier systems, especially during the night, and have been observed to occupy as little as 12 cm per hen on these, leaving ample space available on lower perches ( Steenfeldt and Nielsen, 2015b ; Giersberg et al., 2019 ). Thus, to improve laying hen welfare, it is important not only to provide sufficient perch length but also to consider perch height ( Brendler and Schrader, 2016 ; Riddle et al., 2018 ).

Studies show that broilers, like laying hens, are highly motivated to perch, i.e. to sit in an elevated position ( Kaukonen et al., 2017 ; Malchow et al., 2019 ). The opportunity to perform this behaviour is not only important for animal welfare in itself, but raised sitting levels may also have further positive effects on, for example, leg health ( Bailie et al., 2013 ; Kaukonen et al., 2017 ) and incidences of hock burns and foot pad dermatitis ( Karaarslan and Nazlıgül, 2018 ; Lourenço da Silva et al., 2021 ; Mocz et al., 2022 ). However, not all findings point to such welfare benefits ( Ventura et al., 2010 ; de Jong and Gunnink, 2019 ; de Jong et al., 2021 ), which might be due to differences in terms of number, design and type of items provided for perching, as well as other factors, e.g. strain and stocking density. Elevated structures such as platforms and straw bales seem to increase the performance of active behaviours, including foraging and exploratory behaviours ( Bergmann et al., 2017 ; Vasdal et al., 2019 ; Lourenço da Silva et al., 2021 ). Certain structures may also provide shelter for resting in an otherwise barren environment ( Bergmann et al., 2017 ; Lourenço da Silva et al., 2021 ), and perches and platforms have been shown to decrease physical disturbances amongst broilers and, thus, better allow for sufficient rest ( Ventura et al., 2012 ; Forslind, 2023 ). Moreover, increasing the environmental complexity by providing raised sitting levels, which may come in various forms and shapes ( Göransson et al., 2021 ), can increase the expression of behaviours indicative of positive emotions ( Vas et al., 2023 ) and reduce fearfulness of humans in broilers ( Baxter et al., 2020 ; Lourenço da Silva et al., 2021 ). Systematic research concerning the space allowance and number of elevated structures in relation to flock size is limited ( Riber et al., 2018 ). It has been shown that a higher perch space allowance (15 vs 7.5 cm per bird) increases the proportion of broilers in a flock perching, especially at night ( Nielsen, 2004 ). Baxter et al. (2020) provided broilers with platforms (0.5, 0.6 or 0.7 m 2 per 1000 birds, i.e. 5, 6 or 7 cm 2 per bird), and concluded that the additional platforms were used fully and thus resulted in a higher flock level of perching. On average, 11.5 birds per m 2 were using the platforms at any one time, which corresponds to around 870 cm 2 occupied by each broiler ( Baxter et al., 2020 ). Although this might not correspond exactly to the space occupied by slow-growing hybrids on elevated structures of a different sort, it nonetheless shows that providing 5 cm perch or 25 cm 2 raised sitting level per bird only enables a small proportion of the flock to perch simultaneously.

In conclusion, providing an additional 3 cm perch per bird (compared to the 15 cm required in conventional production) seems to improve laying hen welfare, although certain slightly larger hybrids might require more than this. Perching is also an important behaviour in broilers; providing raised sitting areas can e.g. increase leg health, improve rest and reduce fearfulness. Although there is a lack of relevant research, the current space requirements for broilers seem to allow only a small proportion of the flock to perch at any one time.

2.6 Provision of roughage

Livestock in organic production should be fed with feed materials produced in accordance with the rules of organic production, taking into account the physiological needs and nutritional requirements of the animals (EU regulation 2018/848). Moreover, to meet their ethological needs, poultry should be provided with sufficient quantities of roughage whenever they do not have outdoor access or when feed availability from the outdoor area is limited (EU regulation 2018/848).

Roughage (e.g. straw, silage, and lucerne) as a source of (insoluble) dietary fibre has been shown to successfully reduce severe feather pecking and cannibalism in laying hens ( El-Lethey et al., 2000 ; Steenfeldt et al., 2007 ; Patt et al., 2022 but see Schreiter et al., 2019 for review), although a genotype-environment interaction effect has been suggested ( Schreiter et al., 2020 ). A high-fibre diet may increase the time spent eating ( van Krimpen et al., 2008 ) and reduce stress levels ( El-Lethey et al., 2000 ), which likely contributes to the aforementioned positive effect on feather pecking in laying hens ( Desbruslais et al., 2021 ). Moreover, dietary fibre can also improve gut health in both laying hens and broilers by stimulating intestinal development and favouring beneficial intestinal microbiomes (see Desbruslais et al., 2021 and Jha and Mishra, 2021 for reviews). It has been suggested that better gut health may also contribute to reduced feather pecking behaviour in layers, although more research is needed regarding this particular aspect of providing dietary fibre ( Mens et al., 2020 ). In the aforementioned studies, foraging materials have predominantly been provided ad libitum. The EU regulations require that roughage must be provided in “sufficient quantities”, but the protective effect of roughage against severe feather pecking has not been evaluated in terms of specific amounts.

Roughage can function as environmental enrichment and contribute to a more complex environment, which has been associated with improved poultry welfare, for example, due to the higher expression of social play, comfort behaviours and ground-scratching ( Vas et al., 2023 ), and reduced fearfulness ( Nazar et al., 2022 ). More foraging has been observed in broilers given maize roughage compared to those given no or other types of enrichment ( Bach et al., 2019 ). When provided with straw bales, broilers will peck and scratch at these ( Bergmann et al., 2017 ; Baxter et al., 2018 ). However, straw bales seem to be perhaps more important for providing cover and for resting behaviour ( Bailie et al., 2013 ; Bergmann et al., 2017 ), whereas other substrates might better stimulate foraging ( Baxter et al., 2018 ; Holt et al., 2023 ). In terms of foraging substrates, most preference studies in broilers involve different litter types such as peat, wood shaving and chopped straw ( Villagrá et al., 2014 ; Monckton et al., 2020 ; Holt et al., 2023 ), whereas such studies investigating various types and ways of presenting roughage in particular are scarce. Nonetheless, it has been suggested that providing several different substrates, as well as maintaining novelty, is important in order to stimulate ground scratching and curiosity-based inquisitive exploration ( Newberry, 1999 ; Holt et al., 2023 ; Vas et al., 2023 ). On the other hand, it is also important to acknowledge the biosecurity risks associated with providing roughage ( Riber et al., 2018 ), since the risk of infectious disease is also highly relevant for bird health and welfare.

In conclusion, roughage can function as environmental enrichment and provide additional foraging opportunities. As such, roughage can reduce feather pecking and cannibalism in laying hens, and thereby improve poultry welfare, although the format and specific type of roughage provided must be considered. However, knowledge of bird preferences in terms of roughage is limited, especially in broiler chickens.

2.7 Lower stocking density

Organic husbandry practices and housing conditions “shall ensure that the developmental, physiological and ethological needs of the animals are met” (EU regulation 2018/848). The stocking density “shall provide for the comfort, well-being and species-specific needs of the animals”. The maximum stocking density in organic production is 6 birds per m 2 usable area of the indoor area for laying hens, and 21 kg live weight per m 2 indoor usable area for broilers (EU regulation 2020/464).

The substantial amount of research concerning the welfare consequences of housing broilers at different stocking densities shows that, in general, relatively high stocking densities are associated with direct and indirect welfare impairments ( EFSA, 2023a ). However, there is no evident threshold stocking density above which overall welfare is clearly compromised, and appropriate management and other environmental factors in commercial production can, to a certain extent, negate some of the adverse effects of high stocking densities ( Dawkins et al., 2004 ). When comparing 25 kg/m 2 (or 8-10 birds/m 2 ) with relatively higher stocking densities in fast-growing broilers, a number of positive welfare consequences have been found related to lower stocking density, including improvements in gait and skeletal bone quality ( Sun et al., 2013 ), and foot pad health and the prevalence of hock burns ( Ventura et al., 2010 ; Sun et al., 2013 ). Higher activity levels and the use of environmental enrichment ( Ventura et al., 2012 ; de Jong and Goërtz, 2017 ) have also been observed, as well as a reduced frequency of disturbances amongst chickens ( Ventura et al., 2012 ) and an enhanced immune system status ( Gomes et al., 2014 ). Although strain-environment interactions might hamper the direct extrapolation of these results to more slower-growing hybrids ( Rayner et al., 2020 ), similar welfare improvements in terms of health and behaviour have also been associated with lower stocking densities in the latter ( van der Eijk et al., 2022 , 2023 ). Notwithstanding the above, studies in which even lower as well as a wider range of, stocking densities have been evaluated in terms of broiler welfare, show that more pronounced welfare benefits may come from a further decrease in stocking density ( Buijs et al., 2009 , 2010 ). Indeed, EFSA (2023a) recently recommended a maximum stocking density of 11 kg/m 2 in fast-growing broilers. Furthermore, it has been suggested that broilers may perceive the proximity of conspecifics as aversive at a stocking density of 15 kg/m 2 or higher ( Buijs et al., 2011 ).

Stocking density and how it impacts the welfare of laying hens in non-cage systems is, however, not as well researched, and of the relevant studies, only a few include a stocking density of or lower than 6 birds/m 2 . However, in a recent report, EFSA, 2023b ) recommended a maximum stocking density of 4 adult laying hens per m 2 to improve welfare. When hens were housed at either 5, 6, 7 or 10 birds/m 2 in an experimental study, the highest stocking density had adverse effects on egg laying, as well as litter moisture and ammonia emission, and certain blood parameters indicated elevated stress levels in these hens ( Kang et al., 2016 ). It has also been shown that, within the range 4-12 birds/m 2 , relatively lower stocking densities may have a positive effect on range use in laying hens ( Gilani et al., 2014 ; Steenfeldt and Nielsen, 2015a ). Although research findings regarding the correlation between stocking density and severe feather pecking are inconsistent ( EFSA, 2023a ), this behaviour has been found to be lower at 6.7 than at 9.4 birds/m 2 ( Schwarzer et al., 2021 ). However, no evident welfare improvements were observed when different stocking densities (7, 9 or 12 birds/m 2 ) were studied in single-tier aviaries on a commercial farm, indicating that other housing and management factors may have a more profound influence on laying hen welfare ( Nicol et al., 2006 ; Zimmerman et al., 2006 ). Due to behavioural synchronisation within laying hen flocks, the actual stocking density in certain areas of the house may vary largely ( Channing et al., 2001 ). Thus, to increase laying hen welfare in non-cage systems, rather than space allowance per se, an even distribution of resources in sufficient amounts, as well as a system design that counteracts crowding, might be more important ( Nicol et al., 2017 ). Moreover, behavioural differences between strains, for example in terms of resource preferences and anti-predator responses, may also have to be considered ( Ali et al., 2016 ).

In conclusion, the lower stocking densities in organic production may contribute to improved poultry welfare in terms of health and behavioural freedom, especially for broiler chickens, as compared to conventional production in which relatively higher stocking densities are permitted. More pronounced welfare benefits may come from the use of even lower stocking densities though. Moreover, a housing system designed to promote an even distribution of birds might be just as important for laying hen welfare.

3 Discussion and animal welfare implications

Organic agriculture is associated with high animal welfare standards, which can be found embedded within the four principles of organic production ( Vaarst and Alrøe, 2012a ). The organic principles, in turn, have been embodied in organic standards such as the EU regulations on organic production to reflect the underlying values of the organic movement at the farm level ( Vaarst et al., 2004 ). The aim of this paper was to assess and discuss how the key features of organic poultry production, as stipulated in the current EU regulations, relate to contemporary animal welfare scientific knowledge.

3.1 Mitigating negatives and promoting positives

In general, the scientific evidence at hand shows that some of the key features of organic poultry production may indeed contribute to improved bird welfare – not only by mitigating certain negative aspects of chicken meat and egg production, but also by promoting positive and pleasant experiences. For instance, the use of more slow-growing broiler hybrids has resulted in improved leg health, and thereby reduced lameness associated pain ( Caplen et al., 2013 ; Dixon, 2020 ). Due to improved physical mobility in combination with a relatively lower stocking density, these slower-growing broilers are able to perform, for example, more exploratory and play behaviours ( Dawson et al., 2021 ). Moreover, the emphasis on opportunities to perform natural behaviours in organic animal farming, e.g. through the provision of raised sitting areas also for broilers, outdoor access and roughage, may improve poultry welfare by enabling the animals to engage in highly motivated behaviours that they find rewarding ( Špinka, 2006 ; Mellor, 2015a ), such as perching, dust bathing and foraging ( Weeks and Nicol, 2006 ).

Also based on the EU regulations on organic farming, Duval et al. (2020) came to a somewhat similar conclusion in terms of potentially higher animal welfare within the organic dairy industry. Murphy and Legrand (2023) recently introduced the concept of “welfare potential” of a production system, referring to its inherent ability to ensure the welfare of animals, taking into account the three welfare approaches of biological functioning, natural living and subjective feelings. Thus, a production system that offers greater opportunities for the animals to perform highly motivated behaviours and for positive experiences, as in organic poultry production, increases its “welfare potential” ( Murphy and Legrand, 2023 ).

3.2 Room for improvement

Notwithstanding the welfare benefits associated with some of the key features of organic poultry production, several of these areas exhibit some room for improvement. For instance, while relatively low stocking densities may have positive consequences for poultry welfare in terms of both health and behaviour, research shows that more pronounced welfare improvements may come from stocking densities being even lower than those required in EU organic poultry production, as concluded by EFSA (2023a) . Moreover, even if the welfare issues associated with rapid growth rates in broilers have largely been mitigated in the relatively slow-growing hybrids ( Dawson et al., 2021 ), the latter still shows some gait impairments and lameness ( Göransson et al., 2020 ). The hybrids used in commercial organic production often have an average daily weight gain of around 45-50 g ( Göransson et al., 2020 ), and studies show that using hybrids with even lower growth rates may result in further welfare improvements ( Castellini et al., 2016 ). Although raised sitting levels also bring about important welfare improvements in organic broiler production, the provision of perches and platforms according to the minimum space requirements is insufficient considering the size of commercial flocks ( Göransson et al., 2021 ). Animal welfare is not a relative concept but is the state of an animal on a continuum from poor to good, yet animal welfare regulations are often considered in relation to other regulations (e.g. in other countries, legislation and private standards), rather than relative to what the animals actually need or want to have good welfare ( Mellor, 2015b ). Making a comparison between production systems in terms of overall animal welfare is a challenging task, but by using the Welfare Quality ® assessment protocol, Wagner et al. (2021) concluded that the overall welfare was higher on organic dairy farms than in conventional production. However, it was also concluded that there is room for improvement within organic dairy production, especially with regards to cow health ( Wagner et al., 2021 ). Similarly, many other authors have emphasised that although potential welfare improvements sit within the regulatory framework for organic animal farming, important challenges remain to ensure a high level of welfare ( Sundrum, 2001 ; Hovi et al., 2003 ; Marley et al., 2010 ; Duval et al., 2020 ; Åkerfeldt et al., 2021 ). The organic standards might allow for a relatively higher level of animal welfare due to a relatively higher level of minimum requirements than other regulations, but it does not necessarily guarantee a good or the best possible animal welfare from the animals’ point of view. Animal welfare regulations are the outcome of compromises between scientific knowledge, values, traditions, consumer demands, practicability and economy ( Croney and Millman, 2007 ; Yeates et al., 2011 ; Lundmark et al., 2014 ). This might result in goal conflicts between the intentions of a regulation and the actual requirements ( Waiblinger et al., 2007 ; Vaarst and Alrøe, 2012b ; Lundmark et al., 2014 ), i.e. between the fundamental values of organic production and what is in fact feasible at the farm level. Thus, while high animal welfare standards are important in organic farming, the interests of other stakeholders must also be taken into account, and therefore the magnitude of the welfare improvements to be made within the context of modern commercial poultry production might be limited ( Appleby, 2019 ). Relatively higher welfare standards within organic animal farming might nonetheless place pressure on and contribute to welfare improvements in the standards for conventional production ( Duval et al., 2020 ).

3.3 Two sides of the same coin

Some of the key features of organic poultry production intended to increase animal welfare, such as outdoor access and the ban on mutilations, are sometimes put forth as being disadvantageous for bird welfare ( Riber and Hinrichsen, 2017 ; Bonnefous et al., 2022 ). For instance, outdoor access includes the risk of predators and infectious disease transmission, which can have detrimental consequences for bird welfare. However, notwithstanding these perils, appropriate management of the free-range can at least mitigate these risks to a certain extent, e.g. through appropriate fences to protect against ground predators and avoiding puddles or pools of water as a measure to improve biosecurity ( Bonnefous et al., 2022 ). Marley et al. (2010) discussed the advantages and disadvantages of pasture access for dairy cows in organic production, and emphasised too that appropriate management of the outdoor area is vital in order to reduce the risk of compromised animal health and welfare. Since the damages and injuries resulting from severe feather pecking and cannibalism have been shown to be lower in beak-trimmed flocks ( Riber and Hinrichsen, 2017 ; van Staaveren et al., 2021 ), the banning of beak trimming in organic egg production may be considered problematic from an animal welfare perspective. However, the procedure does not prevent the behaviour, which is still evident in mutilated hens ( Lambton et al., 2010 , 2013 ). Many have concluded that beak trimming should not be necessary if good management practices are implemented ( Glatz and Underwood, 2021 ; EFSA, 2023b ), including lower stocking densities, outdoor access and increased foraging opportunities – all of which organic egg production indeed entails. On the other hand, the risk of severe feather pecking might also increase in organic egg production, since organic animal production also entails the prohibition of dietary synthetic amino acids (EU regulation 2018/848). Insufficient protein levels and amino acid imbalances have been associated with severe feather pecking in laying hens ( Van Krimpen et al., 2005 ; Mens et al., 2020 ). Moreover, essential amino acids, such as lysine, methionine and tryptophan, are vital for normal feather synthesis, intestinal development and gut health, immune system function and protection against oxidative stress, and must be provided in the poultry diet (see Alagawany et al., 2021 for a review). However, since protein sources produced according to organic standards are limited, and due to the prohibition of synthetic amino acids in organic feedstuff, the formulation of a well-balanced diet that meets the nutritional requirements of poultry is a major challenge in organic production ( van Krimpen et al., 2016 ).

3.4 Degrees of naturalness

As previously discussed, the strong emphasis on naturalness and natural living in organic agriculture may in several ways improve poultry welfare through, for example, outdoor access, natural light and better foraging and perching opportunities. It is common for animal welfare regulations, in organic and non-organic animal production, to include some kind of requirements concerning the animals’ ability to behave naturally ( Lundmark et al., 2014 ). However, naturalness is often considered to be a quite narrow concept that does not cover all aspects of what is natural for an animal ( Lundmark et al., 2014 ). Indeed, it might be argued that some important aspects of a natural chicken life are missing in commercial (organic) poultry production. For instance, young chicks are hatched in incubators and reared artificially. Not only is the absence of a mother hen highly unnatural, but research shows that natural brooding of chicks has welfare benefits like lower fearfulness and a reduced risk of severe feather pecking (see Edgar et al., 2016 for a review). While natural brooding is not commercially viable, “dark brooders” can be used as a practical on-farm solution to artificially provide certain aspects of maternal care and thereby improve chick welfare. However, these are rarely used in rearing facilities ( Sirovnik and Riber, 2022 ). Similarly, the unnaturalness and welfare implications of the early cow-calf separation in dairy production has been discussed in relation to the organic values ( Marley et al., 2010 ). After hatching, laying hens and broilers are kept in flocks that comprise thousands of birds. Normal social behaviour, which involves the establishment of a pecking order ( Rushen, 1982 ), becomes an impossible task in such large flocks. It has been suggested that laying hens and broilers in commercial production instead adapt a more “tolerant social system” ( Estevez et al., 1997 ; Hughes et al., 1997 ; D’Eath and Keeling, 2003 ). Although the welfare implications of the frequent and recurrent encounters with unfamiliar birds is unclear ( D’Eath and Keeling, 2003 ; Appleby et al., 2004 ), negative welfare consequences for the birds in these highly unnatural large flocks cannot be excluded. Again, the welfare implications and the unnaturalness of the social interactions on large-scale commercial dairy farms has been discussed in relation to the organic values ( Marley et al., 2010 ). The IFOAM organic standards, and in extension the EU regulations on organic production, represent a compromise between the fundamental values of the organic movement and what is in fact feasible at the farm level and within the present market situation ( Vaarst et al., 2004 ). Hence, some aspects of “naturalness” have been deemed both important and feasible, whereas other aspects might not be practicable within the contemporary production context ( Padel et al., 2004 ; Vaarst et al., 2004 ). Considering the aforementioned consequences on normal feather synthesis and severe feather pecking behaviour, the prohibition of synthetic amino acids in organic feedstuff may be considered a negative aspect of “naturalness”. However, the underlying reason for this ban is more complex than mere unnaturalness, including issues of environmental sustainability ( Leming, 2012 ; Benavides et al., 2020 ). It has also been argued the use of dietary synthetic amino acids would enable an increased animal production performance and a subsequent intensification of organic farming, which would be in disagreement with the organic vision and would impair animal welfare in the long-term ( NAHWOA, 2002 ). This again illustrates the goal conflicts that can occur between different areas of concern that a regulation covers, e.g. between animal welfare, environmental protection and food safety ( Lundmark et al., 2014 ), which in extension further reflects the inevitable compromises between different fundamental values that are necessary both in the short and long term in modern organic animal production.

3.5 Actual welfare improvements at the farm level

For poultry welfare to improve in practice, it is important that the potential welfare benefits associated with the aforementioned requirements as stipulated in the EU organic regulations are actually experienced by the birds at the farm level. For instance, outdoor access is not the same as outdoor use, and the mere provision of a free-range area is obviously not sufficient to improve animal welfare; this has also been discussed regarding pasture access for dairy cows ( Wagner et al., 2018 ). Studies show that outdoor areas on commercial organic poultry farms do not always contain appropriate and sufficient overhead protection in the form of vegetation and/or artificial shelters ( Göransson et al., 2021 , 2023 ), making the birds reluctant to enter the free-range or to leave the vicinity of the house ( Dawkins et al., 2003 ; Gilani et al., 2014 ). It is clearly stated in the EU organic regulations that outdoor areas for poultry shall be attractive to the birds and mainly covered with vegetation composed of a diverse range of plants (EU regulation 2020/464). Hence, it is also important that an effective control system is developed to enforce an animal welfare standard ( Main et al., 2014 ). It has previously been concluded that management is one of the most important factors affecting animal welfare at the individual farm level ( Sundrum, 2001 ; Marley et al., 2010 ; Murphy and Legrand, 2023 ), and while outdoor access in particular is an aspect that can be managed at the farm level in order to improve poultry welfare, other factors may be more difficult for the individual farmer to influence. One example is the choice of laying hen hybrids, which, according to the EU organic regulations, should be appropriate for organic production and ensure a high level of animal welfare, whereas in practice there are few alternatives besides the genotypes used in non-organic production ( Fernyhough et al., 2020 ). Hence, although the organic regulations may have higher “welfare potential” on paper ( Murphy and Legrand, 2023 ), some aspects currently fail at an implementation level.

4 Concluding remarks

● In general, the animal welfare science at hand supports the potential for higher animal welfare in organic poultry production, based on the requirements as laid down in the current EU regulations. The minimum requirements discussed may contribute to better poultry welfare not only by mitigating certain negative aspects of chicken meat production and egg production but also by promoting positive and pleasant experiences.

● As in any other intensive poultry production system, animal welfare issues can be found in organic poultry production as well. Research shows that the welfare benefits that the aforementioned requirements bring could be even greater.

● Some aspects of organic poultry production may not only be beneficial for animal welfare but also involve certain risks. Appropriate management strategies are important to reduce those welfare risks.

● For actual welfare improvements experienced by the animals, it is vital that the requirements as stipulated on paper in the organic standards transfer all the way to the commercial farm.

● Some key aspects that may further improve animal welfare in organic poultry production include the use of alternative laying hen hybrids with the potential for better welfare; slow-growing broilers with an even lower growth rate; appropriate management of the free-range areas in practice to ensure that they are used by the birds; additional raised sitting level space allowance for broilers; and the use of “dark brooders” for chicks.

● The future development of organic animal welfare standards is somewhat dependent on the progress of non-organic regulations. If the gap between organic and non-organic production systems becomes too large, in terms of minimum requirements, organic farmers will find it increasingly difficult to compete on the same market as conventional farmers. If the overall legal baseline is raised through changes in non-organic regulations, there might also be room for improvement within the organic standards. The new EU legislation for farm animals currently under development may enable further animal welfare improvements within the organic standards.

Author contributions

LG: Conceptualization, Investigation, Writing – original draft, Writing – review & editing. FLH: Conceptualization, Writing – original draft, Writing – review & editing.

The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article.

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Åkerfeldt M. P., Gunnarsson S., Bernes G., Blanco-Penedo I. (2021). Health and welfare in organic livestock production systems—a systematic mapping of current knowledge. Organic Agric. 11, 105–132. doi: 10.1007/s13165-020-00334-y

CrossRef Full Text | Google Scholar

Alagawany M., Elnesr S. S., Farag M. R., Tiwari R., Yatoo M. I., Karthik K., et al. (2021). Nutritional significance of amino acids, vitamins and minerals as nutraceuticals in poultry production and health – a comprehensive review. Veterinary Q. 41, 1–29. doi: 10.1080/01652176.2020.1857887

Ali A. B. A., Campbell D. L. M., Karcher D. M., Siegford J. M. (2016). Influence of genetic strain and access to litter on spatial distribution of 4 strains of laying hens in an aviary system. Poultry Sci. 95, 2489–2502. doi: 10.3382/ps/pew236

Appleby M. C. (2019). We demand compromise: which achieves more, asking for small or large changes? Anim. Welfare 28, 83–93. doi: 10.7120/09627286.28.1.083

Appleby M. C., Mench J. A., Hughes B. O. (2004). Poultry Behaviour and Welfare (UK: CABI Publishing). doi: 10.1079/9780851996677.0000

Bach M. H., Tahamtani F. M., Pedersen I. J., Riber A. B. (2019). Effects of environmental complexity on behaviour in fast-growing broiler chickens. Appl. Anim. Behav. Sci. 219, 104840. doi: 10.1016/j.applanim.2019.104840

Bailie C. L., Ball M. E. E., O’Connell N. E. (2013). Influence of the provision of natural light and straw bales on activity levels and leg health in commercial broiler chickens. Animal 7, 618–626. doi: 10.1017/S1751731112002108

PubMed Abstract | CrossRef Full Text | Google Scholar

Baxter M., Bailie C. L., O’Connell N. E. (2018). Evaluation of a dustbathing substrate and straw bales as environmental enrichments in commercial broiler housing. Appl. Anim. Behav. Sci. 200, 78–85. doi: 10.1016/j.applanim.2017.11.010

Baxter M., Richmond A., Lavery U., O’Connell N. E. (2020). Investigating optimal levels of platform perch provision for windowed broiler housing. Appl. Anim. Behav. Sci. 225, 104967. doi: 10.1016/j.applanim.2020.104967

Baxter M., Richmond A., Lavery U., O’Connell N. E. (2021). A comparison of fast growing broiler chickens with a slower-growing breed type reared on Higher Welfare commercial farms. PloS One 16, e0259333. doi: 10.1371/journal.pone.0259333

Bayram A., Özkan S. (2010). Effects of a 16-hour light, 8-hour dark lighting schedule on behavioral traits and performance in male broiler chickens. J. Appl. Poultry Res. 19, 263–273. doi: 10.3382/japr.2009-00026

Benavides P. T., Cai H., Wang M., Bajjalieh N. (2020). Life-cycle analysis of soybean meal, distiller-dried grains with solubles, and synthetic amino acid-based animal feeds for swine and poultry production. Anim. Feed Sci. Technol. 268, 114607. doi: 10.1016/j.anifeedsci.2020.114607

Bergmann S., Schwarzer A., Wilutzky K., Louton H., Bachmeier J., Schmidt P., et al. (2017). Behavior as welfare indicator for the rearing of broilers in an enriched husbandry environment—A field study. J. Veterinary Behav. 19, 90–101. doi: 10.1016/j.jveb.2017.03.003

Bestman M., Bikker-Ouwejan J. (2020). Predation in organic and free-range egg production. Animals 10, 177. doi: 10.3390/ani10020177

Bestman M., Verwer C., Brenninkmeyer C., Willett A., Hinrichsen L. K., Smajlhodzic F., et al. (2017). Feather-pecking and injurious pecking in organic laying hens in 107 flocks from eight European countries. Anim. Welfare 26, 355–363. doi: 10.7120/09627286.26.3.355

Bestman M., Wagenaar J. P. (2014). Health and welfare in dutch organic laying hens. Anim. 4, 374–390. doi: 10.3390/ani4020374

Bonnefous C., Collin A., Guilloteau L. A., Guesdon V., Filliat C., Réhault-Godbert S., et al. (2022). Welfare issues and potential solutions for laying hens in free range and organic production systems: A review based on literature and interviews. Front. Veterinary Sci. 9. doi: 10.3389/fvets.2022.952922

Brendler C., Schrader L. (2016). Perch use by laying hens in aviary systems. Appl. Anim. Behav. Sci. 182, 9–14. doi: 10.1016/j.applanim.2016.06.002

Brinker T., Bijma P., Visscher J., Rodenburg T. B., Ellen E. D. (2014). Plumage condition in laying hens: genetic parameters for direct and indirect effects in two purebred layer lines. Genet. Selection Evol. 46, 33. doi: 10.1186/1297-9686-46-33

Brown A. A., Sobotik E. B., House G. M., Nelson J. R., Archer G. S. (2022). Differences in fear response strategy and stress susceptibility amongst four different commercial layer strains reared cage free. Front. Physiol. 13. doi: 10.3389/fphys.2022.943471

Buijs S., Keeling L., Rettenbacher S., Van Poucke E., Tuyttens F. A. M. (2009). Stocking density effects on broiler welfare: Identifying sensitive ranges for different indicators. Poultry Sci. 88, 1536–1543. doi: 10.3382/ps.2009-00007

Buijs S., Keeling L. J., Vangestel C., Baert J., Tuyttens F. A. M. (2011). Neighbourhood analysis as an indicator of spatial requirements of broiler chickens. Appl. Anim. Behav. Sci. 129, 111–120. doi: 10.1016/j.applanim.2010.11.017

Buijs S., Keeling L. J., Vangestel C., Baert J., Vangeyte J., Tuyttens F. A. M. (2010). Resting or hiding? Why broiler chickens stay near walls and how density affects this. Appl. Anim. Behav. Sci. 124, 97–103. doi: 10.1016/j.applanim.2010.02.007

Campbell D. L. M., Hinch G. N., Downing J. A., Lee C. (2017). Outdoor stocking density in free-range laying hens: effects on behaviour and welfare. Animal 11, 1036–1045. doi: 10.1017/S1751731116002342

Caplen G., Colborne G. R., Hothersall B., Nicol C. J., Waterman-Pearson A. E., Weeks C. A., et al. (2013). Lame broiler chickens respond to non-steroidal anti-inflammatory drugs with objective changes in gait function: A controlled clinical trial. Veterinary J. 196, 477–482. doi: 10.1016/j.tvjl.2012.12.007

Castellini C., Mugnai C., Moscati L., Mattioli S., Amato M. G., Mancinelli A. C., et al. (2016). Adaptation to organic rearing system of eight different chicken genotypes: behaviour, welfare and performance. Ital. J. Anim. Sci. 15, 37–46. doi: 10.1080/1828051X.2015.1131893

Channing C. E., Hughes B. O., Walker A. W. (2001). Spatial distribution and behaviour of laying hens housed in an alternative system. Appl. Anim. Behav. Sci. 72, 335–345. doi: 10.1016/S0168-1591(00)00206-9

Cook N., Schaefer A., Korver D., Haley D., Feddes J., Church J. (2011). Minimally-invasive assessments of the behavioural and physiological effects of enriched colony cages on laying hens. Open Agric. J. 5, 10–18. doi: 10.2174/1874331501105010010

Croney C. C., Millman S. T. (2007). Board-invited review: the ethical and behavioral bases for farm animal welfare legislation. J. Anim. Sci. 85, 556–565. doi: 10.2527/jas.2006-422

Dal Bosco A., Mugnai C., Rosati A., Paoletti A., Caporali S., Castellini C. (2014). Effect of range enrichment on performance, behavior, and forage intake of free-range chickens. J. Appl. Poultry Res. 23, 137–145. doi: 10.3382/japr.2013-00814

Dawkins M. S., Cook P. A., Whittingham M. J., Mansell K. A., Harper A. E. (2003). What makes free-range broiler chickens range? In situ measurement of habitat preference. Anim. Behav. 66, 151–160. doi: 10.1006/anbe.2003.2172

Dawkins M., Donnelly C., Jones T. A. (2004). Chicken welfare is influenced more by housing conditions than by stocking density. Nature 427, 342–344. doi: 10.1038/nature02226

Dawson L. C., Widowski T. M., Liu Z., Edwards A. M., Torrey S. (2021). In pursuit of a better broiler: a comparison of the inactivity, behavior, and enrichment use of fast- and slower growing broiler chickens. Poultry Sci. 100, 101451. doi: 10.1016/j.psj.2021.101451

D’Eath R. B., Keeling L. J. (2003). Social discrimination and aggression by laying hens in large groups: from peck orders to social tolerance. Appl. Anim. Behav. Sci. 84, 197–212. doi: 10.1016/j.applanim.2003.08.010

de Jong I. C., Blaauw X. E., van der Eijk J. A. J., Souza da Silva C., van Krimpen M. M., Molenaar R., et al. (2021). Providing environmental enrichments affects activity and performance, but not leg health in fast- and slower-growing broiler chickens. Appl. Anim. Behav. Sci. 241, 105375. doi: 10.1016/j.applanim.2021.105375

de Jong I. C., Goërtz M. (2017). “Broiler chicken stocking density affects use of environmental enrichment objects,” in Xth European Symposium on Poultry Welfare, Ploufragan, France, 19-22 June 2017.

Google Scholar

de Jong I. C., Gunnink H. (2019). Effects of a commercial broiler enrichment programme with or without natural light on behaviour and other welfare indicators. Animal 13, 384–391. doi: 10.1017/S1751731118001805

De Koning C., Kitessa S. M., Barekatain R., Drake K. (2018). Determination of range enrichment for improved hen welfare on commercial fixed-range free-range layer farms. Anim. Production Sci. 59, 1336–1348. doi: 10.1071/AN17757

Dennis R. L., Cheng H. W. (2012). Effects of different infrared beak treatment protocols on chicken welfare and physiology. Poultry Sci. 91, 1499–1505. doi: 10.3382/ps.2011-01651

Desbruslais A., Wealleans A., Gonzalez-Sanchez D., di Benedetto M. (2021). Dietary fibre in laying hens: a review of effects on performance, gut health and feather pecking. World’s Poultry Sci. J. 77, 797–823. doi: 10.1080/00439339.2021.1960236

Dixon L. M. (2020). Slow and steady wins the race: The behaviour and welfare of commercial faster growing broiler breeds compared to a commercial slower growing breed. PloS One 15, e0231006. doi: 10.1371/journal.pone.0231006

Dudde A., Schrader L., Weigend S., Matthews L. R., Krause E. T. (2018). More eggs but less social and more fearful? Differences in behavioral traits in relation to the phylogenetic background and productivity level in laying hens. Appl. Anim. Behav. Sci. 209, 65–70. doi: 10.1016/j.applanim.2018.08.017

Duval E., von Keyserlingk M. A. G., Lecorps B. (2020). Organic dairy cattle: do European union regulations promote animal welfare? Animals 10, 1786. doi: 10.3390/ani10101786

Duve L. R., Steenfeldt S., Thodberg K., Nielsen B. L. (2011). Splitting the scotoperiod: effects on feeding behaviour, intestinal fill and digestive transit time in broiler chickens. Br. Poultry Sci. 52, 1–10. doi: 10.1080/00071668.2010.549671

Edgar J., Held S., Jones C., Troisi C. (2016). Influences of maternal care on chicken welfare. Anim. (Basel) 6(1), 2. doi: 10.3390/ani6010002

EFSA (2017). Avian influenza overview October 2016–August 2017. EFSA Journal 15, 10, 5018. doi: 10.2903/j.efsa.2017.5018

EFSA (2023a). Welfare of broilers on farm. EFSA J. 21, e07788. doi: 10.2903/j.efsa.2023.7788

EFSA (2023b). Welfare of laying hens on farm. EFSA J. 21, e07789. doi: 10.2903/j.efsa.2023.7789

El-Lethey H., Aerni V., Jungi T. W., Wechsler B. (2000). Stress and feather pecking in laying hens in relation to housing conditions. Br. Poult Sci. 41, 22–28. doi: 10.1080/00071660086358

Estevez I., Newberry R., Rayna L. (1997). Broiler chickens: A tolerant social system? Etologia 5, 19–29.

Fernyhough M., Nicol C. J., van de Braak T., Toscano M. J., Tønnessen M. (2020). The ethics of laying hen genetics. J. Agric. Environ. Ethics 33, 15–36. doi: 10.1007/s10806-019-09810-2

Ferreira V. H. B., Simoni A., Germain K., Leterrier C., Lansade L., Collin A., et al. (2022). Foraging behavior shows individual-consistency over time, and predicts range use in slow-growing free-range male broiler chickens. Front. Veterinary Sci. 9. doi: 10.3389/fvets.2022.814054

Forslind S. (2023). Never wake a sleeping broiler – an undisturbed natural resting pattern in broilers . Swedish University of Agricultural Sciences, Uppsala, Sweden. Available at: https://pub.epsilon.slu.se/30324/1/forslind-s-20230302.pdf . doi: 10.54612/a.p7dvv4us20

Freire R., Eastwood M. A., Joyce M. (2011). Minor beak trimming in chickens leads to loss of mechanoreception and magnetoreception1. J. Anim. Sci. 89, 1201–1206. doi: 10.2527/jas.2010-3129

Gentle M. J. (1989). Cutaneous sensory afferents recorded from the nervus intramandibularis of Gallus gallus var domesticus. J. Comp. Physiol. A 164, 763–774. doi: 10.1007/BF00616748

Gentle M. J., Hughes B. O., Fox A., Waddington D. (1997). Behavioural and anatomical consequences of two beak trimming methods in 1- and 10-d-old domestic chicks. Br. Poultry Sci. 38, 453–463. doi: 10.1080/00071669708418022

Gentle M. J., McKeegan D. E. F. (2007). Evaluation of the effects of infrared beak trimming in broiler breeder chicks. Veterinary Rec. 160, 145–148. doi: 10.1136/vr.160.5.145

Giersberg M. F., Spindler B., Kemper N. (2019). Linear space requirements and perch use of conventional layer hybrids and dual-purpose hens in an aviary system. Front. Veterinary Sci. 6. doi: 10.3389/fvets.2019.00231

Giersberg M. F., Spindler B., Kemper N. (2020a). Are dual-purpose hens less fearful than conventional layer hybrids? Vet. Rec 187, e35. doi: 10.1136/vr.105790

Giersberg M. F., Spindler B., Rodenburg B., Kemper N. (2020b). The dual-purpose hen as a chance: avoiding injurious pecking in modern laying hen husbandry. Animals 10, 16. doi: 10.3390/ani10010016

Gilani A. M., Knowles T. G., Nicol C. J. (2014). Factors affecting ranging behaviour in young and adult laying hens. Br. Poultry Sci. 55, 127–135. doi: 10.1080/00071668.2014.889279

Glatz P., Hinch G. (2008). “Minimise cannibalism using innovative beak trimming methods,” in Final report Project no. 04- 20 (Australian Poultry CRC, Armidale, NSW, Australia). Available at: https://www.poultryhub.org/content/uploads/2012/07/Final-Report-04-20.pdf .

Glatz P. C., Underwood G. (2021). Current methods and techniques of beak trimming laying hens, welfare issues and alternative approaches. Anim. Production Sci. 61, 968–989. doi: 10.1071/AN19673

Gomes A. V. S., Quinteiro-Filho W. M., Ribeiro A., Ferraz-de-Paula V., Pinheiro M. L., Baskeville E., et al. (2014). Overcrowding stress decreases macrophage activity and increases Salmonella Enteritidis invasion in broiler chickens. Avian Pathol. 43, 82–90. doi: 10.1080/03079457.2013.874006

Gonzales J. L., Elbers A. R. W., Beerens N. (2017). Risk factors of primary introduction of highly pathogenic and low pathogenic avian influenza virus into European poultry holdings, considering at least material contaminated by wild birds and contact with wild birds Vol. 14 (Wageningen, the Netherlands: EFSA Supporting Publication, Central Veterinary Institute, Wageningen University), 1282E. doi: 10.2903/sp.efsa.2017.EN-1282

Göransson L., Abeyesinghe S., Gunnarsson S., Yngvesson J. (2023). Easier said than done! Organic farmers consider free-ranging important for laying hen welfare but outdoor areas need more shelter – important gaps between research and practice. Br. Poultry Sci. 4(5), 544–51. doi: 10.1080/00071668.2023.2220650

Göransson L., Gunnarsson S., Wallenbeck A., Yngvesson J. (2021). Behaviour in slower-growing broilers and free-range access on organic farms in Sweden. Animals 11, 2967. doi: 10.3390/ani11102967

Göransson L., Yngvesson J., Gunnarsson S. (2020). Bird health, housing and management routines on Swedish organic broiler chicken farms. Animals 10, 2098. doi: 10.3390/ani10112098

Gouveia K. G., Vaz-Pires P., Martins da Costa P. (2009). Welfare assessment of broilers through examination of haematomas, foot-pad dermatitis, scratches and breast blisters at processing. Anim. Welfare 18, 43–48. doi: 10.1017/S0962728600000051

Grafl B., Polster S., Sulejmanovic T., Pürrer B., Guggenberger B., Hess M. (2017). Assessment of health and welfare of Austrian laying hens at slaughter demonstrates influence of husbandry system and season. Br. Poultry Sci. 58, 209–215. doi: 10.1080/00071668.2017.1280723

Guinat C., Valenzuela Agüí C., Vaughan T. G., Scire J., Pohlmann A., Staubach C., et al. (2022). Disentangling the role of poultry farms and wild birds in the spread of highly pathogenic avian influenza virus in Europe. Virus Evol. 8, veac073. doi: 10.1093/ve/veac073

Güz B. C., de Jong I. C., Da Silva C. S., Veldkamp F., Kemp B., Molenaar R., et al. (2021). Effects of pen enrichment on leg health of fast and slower-growing broiler chickens. PloS One 16, e0254462. doi: 10.1371/journal.pone.0254462

Hofmann T., Schmucker S. S., Bessei W., Grashorn M., Stefanski V. (2020). Impact of housing environment on the immune system in chickens: A review. Animals 10, 1138. doi: 10.3390/ani10071138

Hofmann T., Schmucker S., Sommerfeld V., Huber K., Rodehutscord M., Stefanski V. (2021). Immunomodulatory effects of dietary phosphorus and calcium in two strains of laying hens. Animals 11, 129. doi: 10.3390/ani11010129

Holt P. S. (2021). Centennial Review: A revisiting of hen welfare and egg safety consequences of mandatory outdoor access for organic egg production. Poultry Sci. 100, 101436. doi: 10.1016/j.psj.2021.101436

Holt R. V., Vas J., Vasdal G., Newberry R. C. (2023). A buffet of litters – Broiler chickens behave differently according to litter type and freshness. Appl. Anim. Behav. Sci. 260, 105856. doi: 10.1016/j.applanim.2023.105856

House G. M., Sobotik E. B., Nelson J. R., Archer G. S. (2020). Effect of the addition of ultraviolet light on broiler growth, fear, and stress response. J. Appl. Poultry Res. 29, 402–408. doi: 10.1016/j.japr.2020.01.003

Hovi M., Sundrum A., Thamsborg S. M. (2003). Animal health and welfare in organic livestock production in Europe: current state and future challenges. Livestock Production Sci. 80, 41–53. doi: 10.1016/S0301-6226(02)00320-2

Hughes B. O., Carmichael N. L., Walker A. W., Grigor P. N. (1997). Low incidence of aggression in large flocks of laying hens. Appl. Anim. Behav. Sci. 54, 215–234. doi: 10.1016/S0168-1591(96)01177-X

IFOAM (2024a) International federation of organic movement (IFOAM) - organics international. Available at: https://www.ifoam.bio/ .

IFOAM (2024b) The IFOAM family of standards. Available at: https://www.ifoam.bio/sites/default/files/2020-05/familyframe_web_0.pdf .

Jansson D. S., Nyman A., Vågsholm I., Christensson D., Göransson M., Fossum O., et al. (2010). Ascarid infections in laying hens kept in different housing systems. Avian Pathol. 39, 525–532. doi: 10.1080/03079457.2010.527923

Jha R., Mishra P. (2021). Dietary fiber in poultry nutrition and their effects on nutrient utilization, performance, gut health, and on the environment: a review. J. Anim. Sci. Biotechnol. 12, 51. doi: 10.1186/s40104-021-00576-0

Jung L., Knierim U. (2018). Are practice recommendations for the prevention of feather pecking in laying hens in non-cage systems in line with the results of experimental and epidemiological studies? Appl. Anim. Behav. Sci. 200, 1–12. doi: 10.1016/j.applanim.2017.10.005

Kang H. K., Park S. B., Kim S. H., Kim C. H. (2016). Effects of stock density on the laying performance, blood parameter, corticosterone, litter quality, gas emission and bone mineral density of laying hens in floor pens. Poultry Sci. 95, 2764–2770. doi: 10.3382/ps/pew264

Karaarslan S., Nazlıgül A. (2018). Effects of lighting, stocking density, and access to perches on leg health variables as welfare indicators in broiler chickens. Livestock Sci. 218, 31–36. doi: 10.1016/j.livsci.2018.10.008

Kaukonen E., Norring M., Valros A. (2017). Perches and elevated platforms in commercial broiler farms: use and effect on walking ability, incidence of tibial dyschondroplasia and bone mineral content. Animal 11, 864–871. doi: 10.1017/S1751731116002160

Kjaer J. B., Su G., Nielsen B. L., Sørensen P. (2006). Foot pad dermatitis and hock burn in broiler chickens and degree of inheritance. Poultry Sci. 85, 1342–1348. doi: 10.1093/ps/85.8.1342

Lambton S. L., Knowles T. G., Yorke C., Nicol C. J. (2010). The risk factors affecting the development of gentle and severe feather pecking in loose housed laying hens. Appl. Anim. Behav. Sci. 123, 32–42. doi: 10.1016/j.applanim.2009.12.010

Lambton S. L., Nicol C. J., Friel M., Main D. C. J., McKinstry J. L., Sherwin C. M., et al. (2013). A bespoke management package can reduce levels of injurious pecking in loose-housed laying hen flocks. Veterinary Rec. 172, 423–423. doi: 10.1136/vr.101067

Larsen H., Cronin G., Smith C. L., Hemsworth P., Rault J. L. (2017). Behaviour of free-range laying hens in distinct outdoor environments. Anim. Welfare 26, 255–264. doi: 10.7120/09627286.26.3.255

Leming R. (2012). “Consumer demands: feeding in organic farming,” in Sustainable Agriculture . Ed. Jakobsson C. (Uppsala University, Uppsala, Sweden).

Leotti L. A., Iyengar S. S., Ochsner K. N. (2010). Born to choose: the origins and value of the need for control. Trends Cogn. Sci. 14, 457–463. doi: 10.1016/j.tics.2010.08.001

Lourenço da Silva M. I., Almeida Paz I.C.d. L., Chaves G. H. C., Almeida I.C.d. L., Ouros C., Souza S.R.L.d., et al. (2021). Behaviour and animal welfare indicators of broiler chickens housed in an enriched environment. PloS One 16, e0256963. doi: 10.1371/journal.pone.0256963

Lunam C. A., Glatz P. C., Hsu Y. J. (1996). The absence of neuromas in beaks of adult hens after conservative trimming at hatch. Aust. Vet. J. 74, 46–49. doi: 10.1111/j.1751-0813.1996.tb13734.x

Lund V. (2006). Natural living - a precondition for animal welfare in organic farming. Livestock Production Sci. 100, 71–83. doi: 10.1016/j.livprodsci.2005.08.005

Lund V., Algers B. (2003). Research on animal health and welfare in organic farming—a literature review. Livestock Production Sci. 80, 55–68. doi: 10.1016/S0301-6226(02)00321-4

Lundmark F., Berg C., Schmid O., Behdadi D., Röcklinsberg H. (2014). Intentions and values in animal welfare legislation and standards. J. Agric. Environ. Ethics 27, 991–1017. doi: 10.1007/s10806-014-9512-0

Maddocks S. A., Cuthill I. C., Goldsmith A. R., Sherwin C. M. (2001). Behavioural and physiological effects of absence of ultraviolet wavelengths for domestic chicks. Anim. Behav. 62, 1013–1019. doi: 10.1006/anbe.2001.1842

Main D. C. J., Mullan S., Atkinson C., Cooper M., Wrathall J. H. M., Blokhuis H. J. (2014). Best practice framework for animal welfare certification schemes. Trends Food Sci. Technol. 37, 127–136. doi: 10.1016/j.tifs.2014.03.009

Malchow J., Berk J., Puppe B., Schrader L. (2019). Perches or grids? What do rearing chickens differing in growth performance prefer for roosting? Poultry Sci. 98, 29–38. doi: 10.3382/ps/pey320

Marchant-Forde R. M., Fahey A. G., Cheng H. W. (2008). Comparative effects of infrared and one-third hot-blade trimming on beak topography, behavior, and growth. Poult Sci. 87, 1474–1483. doi: 10.3382/ps.2006-00360

Marley C. L., Weller R. F., Neale M., Main D. C. J., Roderick S., Keatinge R. (2010). Aligning health and welfare principles and practice in organic dairy systems: a review. Animal 4, 259–271. doi: 10.1017/S1751731109991066

McKeegan D. E. F., Philbey A. W. (2012). Chronic neurophysiological and anatomical changes associated with infrared beak treatment and their implications for laying hen welfare. Anim. Welfare 21, 207–217. doi: 10.7120/09627286.21.2.207

Mellor D. J. (2015a). Positive animal welfare states and encouraging environment-focused and animal-to-animal interactive behaviours. New Z. Veterinary J. 63, 9–16. doi: 10.1080/00480169.2014.926800

Mellor D. J. (2015b). Positive animal welfare states and reference standards for welfare assessment. New Z. Veterinary J. 63, 17–23. doi: 10.1080/00480169.2014.926802

Mens A. J. W., van Krimpen M. M., Kwakkel R. P. (2020). Nutritional approaches to reduce or prevent feather pecking in laying hens: any potential to intervene during rearing? World’s Poultry Sci. J. 76, 591–610. doi: 10.1080/00439339.2020.1772024

Mocz F., Michel V., Janvrot M., Moysan J. P., Keita A., Riber A. B., et al. (2022). Positive effects of elevated platforms and straw bales on the welfare of fast-growing broiler chickens reared at two different stocking densities. Anim. (Basel) 12(5), 542. doi: 10.3390/ani12050542

Monckton V., van Staaveren N., Harlander-Matauschek A. (2020). Broiler chicks’ Motivation for different wood beddings and amounts of soiling. Animals 10, 1039. doi: 10.3390/ani10061039

Murphy E., Legrand A. (2023). Introduction to the concept of “welfare potential” of production systems and its practical relevance to welfare labelling. Front. Anim. Sci. 4. doi: 10.3389/fanim.2023.1225839

NAHWOA (2002). Network for Animal Health and Welfare in Organic Agriculture: Statement concerning the ban on inclusion of synthetic amino acids in the diets of organically reared monogastric (poultry and pigs) livestock in the EU Regulation 1804/99 . Available at: http://www.veeru.reading.ac.uk/organic/AAStatementAppend.pdf .

Nazar F. N., Skånberg L., McCrea K., Keeling L. J. (2022). Increasing environmental complexity by providing different types of litter and perches during early rearing boosts coping abilities in domestic fowl chicks. Animals 12, 1969. doi: 10.3390/ani12151969

Nelson J. R., Settar P., Berger E., Wolc A., O’Sullivan N., Archer G. S. (2020). Brown and white egg-layer strain differences in fearfulness and stress measures. Appl. Anim. Behav. Sci. 231, 105087. doi: 10.1016/j.applanim.2020.105087

Newberry R. (1999). Exploratory behaviour of young domestic fowl. Appl. Anim. Behav. Sci. 63, 311–321. doi: 10.1016/S0168-1591(99)00016-7

Newberry R. C., Estevez I., Keeling L. J. (2001). Group size and perching behaviour in young domestic fowl. Appl. Anim. Behav. Sci. 73, 117–129. doi: 10.1016/S0168-1591(01)00135-6

Nicol C. J., Brown S. N., Glen E., Pope S. J., Short F. J., Warriss P. D., et al. (2006). Effects of stocking density, flock size and management on the welfare of laying hens in single-tier aviaries. Br. Poultry Sci. 47, 135–146. doi: 10.1080/00071660600610609

Nicol C., Caplen G., Trevarthen A., Hockenhull J., L, L., Lines J., S, M., Weeks C., et al. (2017). “Farmed bird welfare science review,” in The Department of Economic Development, Jobs, Transport and Resources (Melbourne, Victoria, Australia). Available at: https://agriculture.vic.gov.au/__data/assets/pdf_file/0008/529829/Farmed-Bird-Welfare-Science-Review.pdf .

Nielsen B. (2004). Breast blisters in groups of slow-growing broilers in relation to strain and the availability and use of perches. Br. Poultry Sci. 45, 306–315. doi: 10.1080/00071660410001730798

Olsson I. A., Keeling L. J. (2000). Night-time roosting in laying hens and the effect of thwarting access to perches. Appl. Anim. Behav. Sci. 68, 243–256. doi: 10.1016/S0168-1591(00)00097-6

Padel S., Schmid O., Lund V. (2004). “Organic livestock standards,” in Animal health and welfare in organic agriculture . Eds. Vaarst M., Roderick S., Lund V., Lockeretz W. (CAB International, UK).

Pagazaurtundua A., Warriss P. D. (2006). Levels of foot pad dermatitis in broiler chickens reared in 5 different systems. Br. Poultry Sci. 47, 529–532. doi: 10.1080/00071660600963024

Patt A., Halle I., Dudde A., Olbrich A., Sieburg-Rockel J., Krause E. T. (2022). Influence of different dietary fibre contents in the diet on feather pecking, locomotor activity and performance of laying hens. Br. Poultry Sci. 63, 571–580. doi: 10.1080/00071668.2022.2076212

Prescott N. B., Wathes C. M. (1999a). Reflective properties of domestic fowl (Gallus g. domesticus), the fabric of their housing and the characteristics of the light environment in environmentally controlled poultry houses. Br. Poultry Sci. 40, 185–193. doi: 10.1080/00071669987584

Prescott N. B., Wathes C. M. (1999b). Spectral sensitivity of the domestic fowl (Gallus g. domesticus). Br. Poultry Sci. 40, 332–339. doi: 10.1080/00071669987412

Rana M. S., Campbell D. L. M. (2021). Application of ultraviolet light for poultry production: A review of impacts on behavior, physiology, and production. Front. Anim. Sci. 2. doi: 10.3389/fanim.2021.699262

Rayner A. C., Newberry R. C., Vas J., Mullan S. (2020). Slow-growing broilers are healthier and express more behavioural indicators of positive welfare. Sci. Rep. 10, 15151. doi: 10.1038/s41598-020-72198-x

Riber A. B., Hinrichsen L. K. (2017). Welfare consequences of omitting beak trimming in barn layers. Front. Veterinary Sci. 4. doi: 10.3389/fvets.2017.00222

Riber A. B., van de Weerd H. A., de Jong I. C., Steenfeldt S. (2018). Review of environmental enrichment for broiler chickens. Poultry Sci. 97, 378–396. doi: 10.3382/ps/pex344

Riddle E. R., Ali A. B. A., Campbell D. L. M., Siegford J. M. (2018). Space use by 4 strains of laying hens to perch, wing flap, dust bathe, stand and lie down. PloS One 13, e0190532. doi: 10.1371/journal.pone.0190532

Rieke L., Spindler B., Zylka I., Kemper N., Giersberg M. F. (2021). Pecking behavior in conventional layer hybrids and dual-purpose hens throughout the laying period. Front. Veterinary Sci. 8. doi: 10.3389/fvets.2021.660400

Rodriguez-Aurrekoetxea A., Estevez I. (2016). Use of space and its impact on the welfare of laying hens in a commercial free-range system. Poultry Sci. 95, 2503–2513. doi: 10.3382/ps/pew238

Rushen J. (1982). The peck orders of chickens: How do they develop and why are they linear? Anim. Behav. 30, 1129–1137. doi: 10.1016/S0003-3472(82)80203-0

Sarica M., Yamak U., Boz M. (2014). Effect of production systems on foot pad dermatitis (FPD) levels among slow-, medium- and fast-growing broilers. Eur. Poultry Sci. 78. doi: 10.1399/eps.2014.52

Savory C. J., Percival D., Yuill I. (2002). Influence of perch space allowance on perching behaviour of laying hens. Br. Poultry Sci. 43, 22–23. doi: 10.1080/000716602762388455

Schmucker S., Hofmann T., Sommerfeld V., Huber K., Rodehutscord M., Stefanski V. (2021). Immune parameters in two different laying hen strains during five production periods. Poultry Sci. 100, 101408. doi: 10.1016/j.psj.2021.101408

Schreiter R., Damme K., Freick M. (2020). Edible environmental enrichments in littered housing systems: do their effects on integument condition differ between commercial laying hen strains? Animals 10, 2434. doi: 10.3390/ani10122434

Schreiter R., Damme K., von Borell E., Vogt I., Klunker M., Freick M. (2019). Effects of litter and additional enrichment elements on the occurrence of feather pecking in pullets and laying hens – A focused review. Veterinary Med. Sci. 5, 500–507. doi: 10.1002/vms3.184

Schuck-Paim C., Negro-Calduch E., Alonso W. J. (2021). Laying hen mortality in different indoor housing systems: a meta-analysis of data from commercial farms in 16 countries. Sci. Rep. 11, 3052. doi: 10.1038/s41598-021-81868-3

Schwarzer A., Plattner C., Bergmann S., Rauch E., Erhard M., Reese S., et al. (2021). Feather pecking in non-beak-trimmed and beak-trimmed laying hens on commercial farms with aviaries. Animals 11, 3085. doi: 10.3390/ani11113085

Schwean-Lardner K., Fancher B. I., Gomis S., Van Kessel A., Dalal S., Classen H. L. (2013). Effect of day length on cause of mortality, leg health, and ocular health in broilers. Poult Sci. 92, 1–11. doi: 10.3382/ps.2011-01967

Schwean-Lardner K., Fancher B. I., Laarveld B., Classen H. L. (2014). Effect of day length on flock behavioural patterns and melatonin rhythms in broilers. Br. Poultry Sci. 55, 21–30. doi: 10.1080/00071668.2013.860211

Sepeur S., Spindler B., Schulze-Bisping M., Habig C., Andersson R., Beyerbach M., et al. (2015). Comparison of plumage condition of laying hens with intact and trimmed beaks kept on commercial farms. Eur. Poultry Sci. 79. doi: 10.1399/eps.2015.116

Sherwin C. M., Nasr M. A. F., Gale E., Petek M., Stafford K., Turp M., et al. (2013). Prevalence of nematode infection and faecal egg counts in free-range laying hens: relations to housing and husbandry. Br. Poultry Sci. 54, 12–23. doi: 10.1080/00071668.2012.757577

Sibanda T. Z., Flavel R., Kolakshyapati M., Welch M., Schneider D., Ruhnke I. (2020). The association between range usage and tibial quality in commercial free-range laying hens. Br. Poultry Sci. 61, 493–501. doi: 10.1080/00071668.2020.1759786

Sirovnik J., Riber A. B. (2022). Why-oh-why? Dark brooders reduce injurious pecking, though are still not widely used in commercial rearing of layer pullets. Animals 12, 1276. doi: 10.3390/ani12101276

Sobotik E. B., Nelson J. R., Archer G. S. (2020). How does ultraviolet light affect layer production, fear, and stress. Appl. Anim. Behav. Sci. 223, 104926. doi: 10.1016/j.applanim.2019.104926

Špinka M. (2006). How important is natural behaviour in animal farming systems? Appl. Anim. Behav. Sci. 100, 117–128. doi: 10.1016/j.applanim.2006.04.006

Steenfeldt S., Kjaer J. B., Engberg R. M. (2007). Effect of feeding silages or carrots as supplements to laying hens on production performance, nutrient digestibility, gut structure, gut microflora and feather pecking behaviour. Br. Poultry Sci. 48, 454–468. doi: 10.1080/00071660701473857

Steenfeldt S., Nielsen B. L. (2015a). Welfare of organic laying hens kept at different indoor stocking densities in a multi-tier aviary system. I: Egg laying, and use of veranda and outdoor area. Animal 9, 1509–1517. doi: 10.1017/S1751731115000713

Steenfeldt S., Nielsen B. L. (2015b). Welfare of organic laying hens kept at different indoor stocking densities in a multi-tier aviary system. II: live weight, health measures and perching. Animal 9, 1518–1528. doi: 10.1017/S1751731115000725

Stratmann A., Fröhlich E. K., Gebhardt-Henrich S. G., Harlander-Matauschek A., Würbel H., Toscano M. J. (2016). Genetic selection to increase bone strength affects prevalence of keel bone damage and egg parameters in commercially housed laying hens. Poult Sci. 95, 975–984. doi: 10.3382/ps/pew026

Struthers S., Gupta A., Gomis S., Herwig E., Schwean-Lardner K. (2019). Understanding how infrared beak treatment affects the beak tissue and the healing response of brown and white feathered layer pullets. Animals 9, 665. doi: 10.3390/ani9090665

Sun Y. Y., Li Y. L., Li D. L., Chen C., Bai H., Xue F. G., et al. (2017). Responses of broilers to the near-continuous lighting, constant 16-h lighting, and constant 16-h lighting with a 2-h night interruption. Livestock Sci. 206, 135–140. doi: 10.1016/j.livsci.2017.10.019

Sun Z. W., Yan L., G Y. Y., Zhao J. P., Lin H., Guo Y. M. (2013). Increasing dietary vitamin D3 improves the walking ability and welfare status of broiler chickens reared at high stocking densities. Poultry Sci. 92, 3071–3079. doi: 10.3382/ps.2013-03278

Sundrum A. (2001). Organic livestock farming: A critical review. Livestock Production Sci. 67, 207–215. doi: 10.1016/S0301-6226(00)00188-3

Taylor P. S., Hemsworth P. H., Groves P. J., Gebhardt-Henrich S. G., Rault J. L. (2018). Ranging behavior relates to welfare indicators pre- and post-range access in commercial free-range broilers. Poultry Sci. 97, 1861–1871. doi: 10.3382/ps/pey060

Taylor P. S., Hemsworth P. H., Groves P. J., Gebhardt-Henrich S. G., Rault J. L. (2020). Frequent range visits further from the shed relate positively to free-range broiler chicken welfare. Animal 14, 138–149. doi: 10.1017/S1751731119001514

Thapa S., Hinrichsen L. K., Brenninkmeyer C., Gunnarsson S., Heerkens J. L. T., Verwer C., et al. (2015). Prevalence and magnitude of helminth infections in organic laying hens (Gallus gallus domesticus) across Europe. Veterinary Parasitol. 214, 118–124. doi: 10.1016/j.vetpar.2015.10.009

Thøfner I. C. N., Dahl J., Christensen J. P. (2021). Keel bone fractures in Danish laying hens: Prevalence and risk factors. PloS One 16, e0256105. doi: 10.1371/journal.pone.0256105

Thuy Diep A., Larsen H., Rault J. L. (2018). Behavioural repertoire of free-range laying hens indoors and outdoors, and in relation to distance from the shed. Aust. Veterinary J. 96, 127–131. doi: 10.1111/avj.12684

Vaarst M., Roderick S., Lund V., Lockeretz W., Hovi M. (2004). “Organic principles and values: the framework for organic animal husbandry,” in Animal health and welfare in organic agriculture . Eds. Vaarst M., Roderick S., Lund V., Lockeretz W. (CAB International, UK).

Vaarst M., Alrøe H. (2012a). Concepts of animal health and welfare in organic livestock systems. J. Agric. Environ. Ethics 25, 1–15. doi: 10.1007/s10806-011-9314-6

Vaarst M., Alrøe H. F. (2012b). Concepts of animal health and welfare in organic livestock systems. J. Agric. Environ. Ethics 25, 333–347. doi: 10.1007/s10806-011-9314-6

van der Eijk J. A. J., Gunnink H., Melis S., van Riel J. W., de Jong I. C. (2022). Reducing stocking density benefits behaviour of fast- and slower-growing broilers. Appl. Anim. Behav. Sci. 257, 105754. doi: 10.1016/j.applanim.2022.105754

van der Eijk J. A. J., van Harn J., Gunnink H., Melis S., van Riel J. W., de Jong I. C. (2023). Fast- and slower-growing broilers respond similarly to a reduction in stocking density with regard to gait, hock burn, skin lesions, cleanliness, and performance. Poultry Sci. 102, 102603. doi: 10.1016/j.psj.2023.102603

Van de Weerd H., Keatinge R., Roderick S. (2009). A review of key health-related welfare issues in organic poultry production. World’s Poultry Sci. J. 65, 649–684. doi: 10.1017/S0043933909000464

Van Krimpen M. M., Kwakkel R. P., Reuvekamp B. F. J., van der Peet-Schwering C. M. C., Den Hartog L. A., Verstegen M. W. A. (2005). Impact of feeding management on feather pecking in laying hens. World’s Poultry Sci. J. 61, 663–686. doi: 10.1079/WPS200478

van Krimpen M. M., Kwakkel R. P., van der Peet-Schwering C. M. C., den Hartog L. A., Verstegen M. W. A. (2008). Low dietary energy concentration, high nonstarch polysaccharide concentration, and coarse particle sizes of nonstarch polysaccharides affect the behavior of feather-pecking-prone laying hens. Poultry Sci. 87, 485–496. doi: 10.3382/ps.2007-00279

van Krimpen M. M., Leenstra F., Maurer V., Bestman M. (2016). How to fulfill EU requirements to feed organic laying hens 100% organic ingredients. J. Appl. Poultry Res. 25, 129–138. doi: 10.3382/japr/pfv048

van Staaveren N., Ellis J., Baes C. F., Harlander-Matauschek A. (2021). A meta-analysis on the effect of environmental enrichment on feather pecking and feather damage in laying hens. Poultry Sci. 100, 397–411. doi: 10.1016/j.psj.2020.11.006

Vas J., BenSassi N., Vasdal G., Newberry R. C. (2023). Better welfare for broiler chickens given more types of environmental enrichments and more space to enjoy them. Appl. Anim. Behav. Sci. 261, 105901. doi: 10.1016/j.applanim.2023.105901

Vasdal G., Vas J., Newberry R. C., Moe R. O. (2019). Effects of environmental enrichment on activity and lameness in commercial broiler production. J. Appl. Anim. Welf Sci. 22, 197–205. doi: 10.1080/10888705.2018.1456339

Ventura B. A., Siewerdt F., Estevez I. (2010). Effects of barrier perches and density on broiler leg health, fear, and performance. Poultry Sci. 89, 1574–1583. doi: 10.3382/ps.2009-00576

Ventura B. A., Siewerdt F., Estevez I. (2012). Access to barrier perches improves behavior repertoire in broilers. PloS One 7, e29826–e29826. doi: 10.1371/journal.pone.0029826

Villagrá A., Olivas I., Althaus R. L., Gómez E. A., Lainez M., Torres A. G. (2014). Behavior of broiler chickens in four different substrates: a choice test. Braz. J. Poultry Sci. 16, 67–75. doi: 10.1590/S1516-635X2014000100010

Wagner K., Brinkmann J., March S., Hinterstoißer P., Warnecke S., Schüler M., et al. (2018). Impact of daily grazing time on dairy cow welfare—Results of the welfare quality ® Protocol. Animals 8, 1. doi: 10.3390/ani8010001

Wagner K., Brinkmann J., Bergschmidt A., Renziehausen C., March S. (2021). The effects of farming systems (organic vs. conventional) on dairy cow welfare, based on the Welfare Quality ® protocol. Animal 15, 100301. doi: 10.1016/j.animal.2021.100301

Waiblinger S., Menke C., Niebuhr K. (2007). “Mutilations in organic animal husbandry: Ethical dilemmas?,” in Sustainable food production and ethics . Eds. Zollitsch W., Winckler C., Waiblinger S., Haslberger A. (Wageningen Academic Publishers, Wageningen), 321–327.

Wallenbeck A., Wilhelmsson S., Jönsson L., Gunnarsson S., Yngvesson J. (2016). Behaviour in one fast-growing and one slower-growing broiler (Gallus gallus domesticus) hybrid fed a high- or low-protein diet during a 10-week rearing period. Acta Agriculturae Scandinavica Section A — Anim. Sci. 66, 168–176. doi: 10.1080/09064702.2017.1303081

Weeks C. A., Nicol C. J. (2006). Behavioural needs, priorities and preferences of laying hens. World’s Poultry Sci. J. 62, 296–307. doi: 10.1079/WPS200598

Wichman A., De Groot R., Håstad O., Wall H., Rubene D. (2021). Influence of different light spectrums on behaviour and welfare in laying hens. Animals 11, 924. doi: 10.3390/ani11040924

Wilhelmsson S., Yngvesson J., Jönsson L., Gunnarsson S., Wallenbeck A. (2019). Welfare Quality ® assessment of a fast-growing and a slower-growing broiler hybrid, reared until 10 weeks and fed a low-protein, high-protein or mussel-meal diet [Article]. Livestock Sci. 219, 71–79. doi: 10.1016/j.livsci.2018.11.010

Wurtz K. E., Thodberg K., Berenjian A., Foldager L., Tahamtani F. M., Riber A. B. (2022). Commercial layer hybrids kept under organic conditions: a comparison of range use, welfare, and egg production in two layer strains. Poult Sci. 101, 102005. doi: 10.1016/j.psj.2022.102005

Yeates J. W., Röcklinsberg H., Gjerris M. (2011). Is welfare all that matters? A discussion of what should be included in policy-making regarding animals. Anim. Welfare 20, 423–432. doi: 10.1017/S0962728600002980

Zimmerman P. H., Lindberg A. C., Pope S. J., Glen E., Bolhuis J. E., Nicol C. J. (2006). The effect of stocking density, flock size and modified management on laying hen behaviour and welfare in a non-cage system. Appl. Anim. Behav. Sci. 101, 111–124. doi: 10.1016/j.applanim.2006.01.005

Keywords: laying hen, broiler, animal housing, management, natural behaviour, legislation, EU regulation

Citation: Göransson L and Lundmark Hedman F (2024) The perks of being an organic chicken – animal welfare science on the key features of organic poultry production. Front. Anim. Sci. 5:1400384. doi: 10.3389/fanim.2024.1400384

Received: 13 March 2024; Accepted: 22 April 2024; Published: 07 May 2024.

Reviewed by:

Copyright © 2024 Göransson and Lundmark Hedman. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Lina Göransson, [email protected]