The DOI matches its Crossref record; 27 of the 27 references it cites were found in a registry or an index.
Echo chambers online?: Politically motivated selective exposure among Internet news users
Open accessAbstract
A review of research suggests that the desire for opinion reinforcement may play a more important role in shaping individuals’ exposure to online political information than an aversion to opinion challenge. The article tests this idea using data collected via a web-administered behavior-tracking study with subjects recruited from the readership of 2 partisan online news sites (N = 727). The results demonstrate that opinion-reinforcing information promotes news story exposure while opinion-challenging information makes exposure only marginally less likely. The influence of both factors is modest, but opinion-reinforcing information is a more important predictor. Having decided to view a news story, evidence of an aversion to opinion challenges disappears: There is no evidence that individuals abandon news stories that contain information with which they disagree. Implications and directions for future research are discussed.
Overview
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Integrity signals
Registry
Cites
Statistics
Verification
Claims the paper makes
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
The cited source doesn’t support the claim as written.
In the citing paper
“Homophily in communication, the tendency of people to communicate with others having similar beliefs, is understood to lead to the formation of echo chambers which reinforce individual beliefs and fuel further increase in polarization.”
From Credibility of climate change denial in social media (2019) · cites this paper as Garrett, 2009
Checked by a reasoning model — may be wrong.
Experimental — accuracy not yet measuredThe cited source doesn’t support the claim as written.
In the citing paper
“For example, homophily among liberals and conservatives in political blogs links (Adamic and Glance, 2005), i.e., the tendency of liberal and conservative blogs to link primarily within their separate communities, leads to echo chambers (Jasny et al., 2015;Garrett, 2009;Flaxman et al., 2016), and hence beliefs can be polarized due to such exposure to selective information (Bakshy et al., 2015).”
From Credibility of climate change denial in social media (2019) · cites this paper as Garrett, 2009
Checked by a reasoning model — may be wrong.
Experimental — accuracy not yet measuredThe source backs part of the claim, not all of it — or backs it for a different population, condition or comparison.
In the citing paper
“Furthermore, users show a tendency to favor information adhering to their beliefs and join groups formed around a shared narrative, that is, echo chambers (1, 14–18).”
From The echo chamber effect on social media (2021) · cites this paper as [15]
Experimental — accuracy not yet measuredThe source backs part of the claim, not all of it — or backs it for a different population, condition or comparison.
In the citing paper
“Estudios basados en encuestas encuentran que el efecto polarizador de la red no deriva de la tendencia de las cámaras de eco, sino más bien de la exposición transversal a los mensajes de personas con ideologías políticas opuestas (Bail y otros, 2018;Garrett, 2009).”
From Polarización, heterogeneidad política y redes sociales en México: un análisis comparativo de #PresidenteRompaElPacto, #FRENA y #RevocacionDeMandato en Twitter (2023) · cites this paper as Garrett, 2009
Experimental — accuracy not yet measuredIn the citing paper
“In social media, such polarized communication networks were observed in controversial debates ranging from political orientation [10, 11], US and French presidential elections [12], or street protests [13].”
From Modeling echo chambers and polarization dynamics in social networks (2020) · cites this paper as [13]
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
The self-check needs the paper’s full text.
Citations
Cites
A Theory of Cognitive Dissonance
Festinger, L. (1957) · doi:10.1515/9781503620766 · Cited by 24,241
Hierarchical Linear Models: Applications and Data Analysis Methods.
Longford, N. T., Bryk, A. S., & Raudenbush, S. W. (1993) · Contemporary Sociology A Journal of Reviews · doi:10.2307/2075823 · Cited by 18,773
A Theory of Cognitive Dissonance
Morvan, C., & O’Connor, A. (2017) · Macat Library eBooks · doi:10.4324/9781912282432 · Cited by 18,284
Hierarchical Linear Models: Applications and Data Analysis Methods
Davidian, M. (2003) · Journal of the American Statistical Association · doi:10.1198/jasa.2003.s288 · Cited by 13,820
Lord, C. G., Ross, L., & Lepper, M. R. (1979) · Journal of Personality and Social Psychology · doi:10.1037/0022-3514.37.11.2098 · Cited by 4,583
Christoph, V. F., Lazarfeld, P. F., Berelson, B., & Gaudet, H. (1945) · The American Catholic Sociological Review · doi:10.2307/3707538 · Cited by 1,732
Hearing the Other Side: Deliberative versus Participatory Democracy
Mutz, D. C. (2006) · doi:10.1017/cbo9780511617201 · Cited by 1,687
Hearing the Other Side: Deliberative versus Participatory Democracy
Mutz, D. C. (2006) · Choice Reviews Online · doi:10.5860/choice.44-2388 · Cited by 1,588
Media Use and Political Predispositions: Revisiting the Concept of Selective Exposure
Stroud, N. J. (2008) · Political Behavior · doi:10.1007/s11109-007-9050-9 · Cited by 1,154
Recent Research on Selective Exposure to Information
Frey, D. (1986) · Advances in experimental social psychology · doi:10.1016/s0065-2601(08)60212-9 · Cited by 820
Research works printed but not linked: 1
- Kohut, 2006, Online papers modestly boost newspaper readership: Maturing Internet news audience-broader than deep
Cited by
Sorted by citations
Items 901–998 of 998
Jungherr, A. M., Rivero, G., & Gayo-Avello, D. (2020) · Cambridge University Press eBooks · doi:10.1017/9781108297820.011
Choosing to AvoidPreprint
Mukerjee, S., & Yang, T. (2020) · doi:10.31219/osf.io/hc2vs
Similar Word Replacement Method for Improving News Commenter Analysis
Lee, D., & Choi, S. (2022) · Applied Sciences · doi:10.3390/app12136803
Medienpädagogik und soziale Netzwerkanalyse
Stegbauer, C. (2022) · Springer eBooks · doi:10.1007/978-3-658-23578-9_19
Ideological homophily and polarization in political Twitter during the 2017 Norwegian electionPreprint
Enjolras, B., & Salway, A. (2022) · Research Square · doi:10.21203/rs.3.rs-1997439/v1
Freedom of Expression in the Age of Digital Platforms: Change of Paradigm?
Lanceiro, R. T. (2022) · Law, governance and technology series · doi:10.1007/978-3-031-07377-9_13
PMP, Violent Conflicts, and Peace Processes
Wolfsfeld, G., Sheafer, T., & Althaus, S. L. (2022) · Oxford University Press eBooks · doi:10.1093/oso/9780197634998.003.0003
Wolfsfeld, G., Sheafer, T., & Althaus, S. L. (2022) · Oxford University Press eBooks · doi:10.1093/oso/9780197634998.003.0007
Wolfsfeld, G., Sheafer, T., & Althaus, S. L. (2022) · Oxford University Press eBooks · doi:10.1093/oso/9780197634998.002.0005
Wolfsfeld, G., Sheafer, T., & Althaus, S. L. (2022) · Oxford University Press eBooks · doi:10.1093/oso/9780197634998.002.0004
The Politics-Media-Politics Approach
Wolfsfeld, G., Sheafer, T., & Althaus, S. L. (2022) · Oxford University Press eBooks · doi:10.1093/oso/9780197634998.003.0001
Wolfsfeld, G., Sheafer, T., & Althaus, S. L. (2022) · Oxford University Press eBooks · doi:10.1093/oso/9780197634998.002.0008
Wolfsfeld, G., Sheafer, T., & Althaus, S. L. (2022) · Oxford University Press eBooks · doi:10.1093/oso/9780197634998.003.0004
Using the PMP Approach to Assess Media Performance in Both Democratic and Autocratic Regimes
Wolfsfeld, G., Sheafer, T., & Althaus, S. L. (2022) · Oxford University Press eBooks · doi:10.1093/oso/9780197634998.003.0006
PMP and Comparative Political Communication
Wolfsfeld, G., Sheafer, T., & Althaus, S. L. (2022) · Oxford University Press eBooks · doi:10.1093/oso/9780197634998.003.0005
Verarbeitung politischer Informationen
Kümpel, A. S., & Unkel, J. (2022) · Springer eBooks · doi:10.1007/978-3-658-26233-4_35
Medienpädagogik und soziale Netzwerkanalyse
Stegbauer, C. (2021) · Springer eBooks · doi:10.1007/978-3-658-25090-4_19-1
Politische Kommunikationsforschung im Wandel
Zerback, T., Marschall, S., Königslöw, K. K., & Borucki, I. R. (2022) · Springer eBooks · doi:10.1007/978-3-658-26233-4_56
Men’s Rights Activism and the Manosphere
O’Donnell, J. (2022) · Springer eBooks · doi:10.1007/978-3-031-14057-0_2
Resources and Partisanship: Response to Commentaries
Baumeister, R. F., & Bushman, B. J. (2023) · Psychological Inquiry · doi:10.1080/1047840x.2023.2192654
El sistema intercomunicacional: de los medios al cambio social mundial
Torres, E. (2023) · Perspectivas de la comunicación · doi:10.56754/0718-4867.2023.3040
Digital Existence and Its Impossible Education and Democracy
Zhao, S. (2023) · Springer eBooks · doi:10.1007/978-3-031-25871-8_4
Post, S., Bienzeisler, N., & Pannach, F. (2023) · New Media & Society · doi:10.1177/14614448231185764
Online Platforms and Analysis of Community Dynamics
Lyubareva, I., & Waldeck, R. (2023) · doi:10.1002/9781394236565.ch1
หองแหงเสยงสะทอนออนไลนกบผออกเสยงเลอกตงครงแรกในการเลอกตงทวไป พ.ศ. 2562
รามสูต, พ., ไชยนันท์, พ., & สุทธิสีมา, ว. (2022) · วารสารสังคมศาสตร์ จุฬาลงกรณ์มหาวิทยาลัย · doi:10.61462/cujss.v52i2.897
The Impact of social media on Political Polarization: A Comparative Analysis
Lokesh, M. R. (2023) · International Journal for Research Publication and Seminars · doi:10.36676/jrps.2023-v14i2-032
From Framing To Enframing: Reflections On The Technical Ethics Of Nudge In Journalism
Jia, C., & Mustafa, H. (2023) · International Journal of Academic Research in Business and Social Sciences · doi:10.6007/ijarbss/v13-i12/19865
La necesidad de definir las nuevas tecnologías deliberativas para el derecho
Major, A. N. S. (2023) · Revista Chilena de Derecho y Tecnología · doi:10.5354/0719-2584.2023.68070
Perspective chapter: Democracy beyond rationality
Polyák, G., & Kövesdi, V. (2024) · IntechOpen eBooks · doi:10.5772/intechopen.1003998
Yeni Medyada Kanaat Önderleri, Görüş Arayanlar Ve Yankı Odaları
ULAŞ, T. (2023) · Özgür Yayınları eBooks · doi:10.58830/ozgur.pub403
Seitz, P., Eisenegger, M., & Bergman, M. M. (2023) · MDPI eBooks · doi:10.3390/books978-3-0365-1347-8
Exploring Groupthink Bias and Polarisation Bias
Aktukun, L. A. (2024) · Advances in human resources management and organizational development book series · doi:10.4018/979-8-3693-1766-2.ch005
The Economics of Social MediaPreprint
Aridor, G., Jiménez-Durán, R., Levy, R., & Song, L. (2024) · SSRN Electronic Journal · doi:10.2139/ssrn.4723727
Ideological Polarization through Selective Exposure: Social Media Perspectives
Mohaimen, A. A., Sultana, S., & Islam, K. D. (2023) · Sudurpaschim Spectrum · doi:10.3126/sudurpaschim.v1i1.63388
Lyu, Z., Nagayoshi, K., & Takikawa, H. (2024) · Translational systems sciences · doi:10.1007/978-981-99-9432-8_7
Polarising punchlines: The influence of inter-group humour on partisan affective polarisationPreprint
Sleiman, Y., Grasso, M. T., Pattie, C. J., Hofer, C., & Serra, L. (2024) · SSRN Electronic Journal · doi:10.2139/ssrn.4769335
Leveraging content producer networks and user perception to detect online discursive communities
Guarino, S., Mounim, A., Caldarelli, G., & Saracco, F. (2026) · Scientific Reports · doi:10.1038/s41598-026-39477-5
Responding to Online Hate—Activism Through Policy
Keighley, R. (2024) · Palgrave hate studies · doi:10.1007/978-3-031-57089-6_6
Starke, A. D., Bremnes, A. S., Knudsen, E., Trilling, D., & Trattner, C. (2024) · ACM Conference on User Modeling, Adaptation and Personalization (UMAP) · doi:10.1145/3631700.3665189
Polarizing reply patterns in comment sections of a large German news outletPreprint
Buder, J., & Anders, G. (2024) · Research Square · doi:10.21203/rs.3.rs-4773834/v1
COVID-19, Social Media Dependency and Desire for Omnipresence: Ways Forward
Mozzini-Alister, C. (2024) · Advances in experimental medicine and biology · doi:10.1007/978-3-031-61943-4_10
Ismaili, Y. (2024) · Journal of international relations and political science studies. · doi:10.69494/jirps.1492964
The Effect of Agenda-Setting on Occurrence of Echo Chamber on Social Media
Nagura, T., & Akiyama, E. (2024) · Transactions of the Japanese Society for Artificial Intelligence · doi:10.1527/tjsai.39-6-ag24-a
Media Capture as an Instrument of Power Culture in Brazil
Moreira, S. V., & Bianco, N. R. D. (2024) · Palgrave studies in journalism and the global South · doi:10.1007/978-3-031-68962-8_4
Machen wir uns die Welt, wie sie uns gefällt?
Knop, K., & Welzenbach-Vogel, I. C. (2019) · merz | medien + erziehung · doi:10.21240/merz/2019.6.7
The Impact of Digital Media on Mass Communication: A Mixed-method Study
Zhu, Y. (2024) · Journal of Education Humanities and Social Sciences · doi:10.54097/yt8x9g64
Online Communication Environment Design for Encouraging Reciprocal Use of Information among Groups
Ichikawa, M., & Takeuchi, Y. (2024) · IEICE Transactions on Information and Systems · doi:10.1587/transinf.2024hcp0010
Kim, H., Jung, W., & Kim, B. (2024) · Korean Journal of Journalism & Communication Studies · doi:10.20879/kjjcs.2024.68.6.001
Jiang, Y., Chen, J., An, S., & Zheng, T. (2025) · SSRN Electronic Journal · doi:10.2139/ssrn.5157744
Echoes on the Internet: Dissecting Social Media Silos through Behavioral and Personality MarkersPreprint
Gao, L. (2025) · Research Square · doi:10.21203/rs.3.rs-5519950/v1
Public value science outcomes: Lessons from the COVID-19 pandemic
Bozeman, B. L. (2025) · ANU Press eBooks · doi:10.22459/bc.2025.03
Dual Narratives on Social Media and the Future of Trust and Reliability in Indian Politics
Dhanapal, K., Sivaprakkash, S., Xavier, N., & Marianand, N. (2025) · IGI Global eBooks · doi:10.4018/979-8-3693-7468-9.ch018
Motivations to connect with like-minded audiences increase partisan sharing on social mediaPreprint
Marie, A., & Petersen, M. B. (2025) · OSF Preprints (OSF Preprints) · doi:10.31219/osf.io/nmg9h_v3
Bias Mitigation and Shifting Ideologies of LLM by Prompting
Ueda, Y., & Suwa, H. (2025) · Communications in computer and information science · doi:10.1007/978-3-031-94171-9_41
Shifting spectrums: how does media consumption alter political orientation?
Martí, J., & Arin, K. P. (2025) · Comparative European Politics · doi:10.1057/s41295-025-00436-5
Filardi, P. V., & Robles, J. M. (2025) · Revista Española de Investigaciones Sociológicas · doi:10.5477/cis/reis.191.113-128 · Cited by 2
Bogado, N., Coninck, D. D., Duque, M., & Schwartz, S. J. (2025) · Research Square · doi:10.21203/rs.3.rs-6881836/v1
Media Exposure Diversity: An Empirical Explication
Jia, X., Pan, Z.-D., & Tu, F.-J. (2025) · Journal of Broadcasting & Electronic Media · doi:10.1080/08838151.2025.2535391
A qualitative analysis of how Just Stop Oil protests are framed in the UK online news media
Handy, H. (2025) · The Plymouth Student Scientist · doi:10.70156/1754-2383.1509
Can Authoritarians’ Electoral Success Abroad Change Citizens’ Satisfaction with Democracy?
Chan, K. (2025) · Political Behavior · doi:10.1007/s11109-025-10071-1 · Cited by 1
Kim, M., & Kim, H. (2025) · SSRN Electronic Journal · doi:10.2139/ssrn.5403378
Political Polarization and Trust in Institutions
Anisin, A. (2025) · Springer eBooks · doi:10.1007/978-3-032-02395-7_4
Disinformation elicits learning biasesPreprint
Vidal-Perez, J., Dolan, R. J., & Moran, R. (2025) · eLife · doi:10.7554/elife.106073.2
Wu, B., Liu, J., Li, Y., Shen‐Zhang, C., & Luan, S. (2025) · PsyCh Journal · doi:10.1002/pchj.70051
Disinformation elicits learning biasesPreprint
Vidal-Perez, J., Dolan, R. J., & Moran, R. (2025) · eLife · doi:10.7554/elife.106073.3
A influence prediction method in social networks with perturbation-constrained learning
Chen, B.-L., Hang, Z., Fang, Z., Liu, B., Hou, Y., & Ji, X. (2025) · Physica A Statistical Mechanics and its Applications · doi:10.1016/j.physa.2025.131139
An empirical study on curbing believability and sharing intention of fake news
Chen, J., Bock, G., & Kim, H.-M. (2025) · Information Technology and Management · doi:10.1007/s10799-025-00475-0
Misinformation, Magic, and Mendacity: Peeking Behind the Curtain to Explore the World of Deception
Draper, P. W., & Zompetti, J. P. (2025) · Anthropology of Consciousness · doi:10.1111/anoc.70025
Wise, K. R., Paltaratskaya, V., & Ji, A. (2025) · De Gruyter eBooks · doi:10.1515/9783111292144-008
Balancing Engagement and Polarization: Multi-Objective Alignment of News Content Using LLMsPreprint
Cheng, M., Ofek, E., & Yoganarasimhan, H. (2025) · RePEc: Research Papers in Economics · doi:10.48550/arxiv.2504.13444 · Cited by 6
Kim, S., Kim, S., & Kim, Y. (2025) · SSRN Electronic Journal · doi:10.2139/ssrn.5451435
Der Bildungsauftrag öffentlich-rechtlicher Medien
Grassmuck, V. R. (2017) · doi:10.59350/5e3x6-fjj14
Der Bildungsauftrag öffentlich-rechtlicher Medien
Grassmuck, V. R. (2017) · doi:10.59350/5vzpq-fbh32
Moreno, C. (2025) · European Journal of Humour Research · doi:10.7592/ejhr.2025.13.4.1081
Holbert, R. L., Rasheed, H., & Scacco, J. M. (2026) · Journal of Broadcasting & Electronic Media · doi:10.1080/08838151.2025.2607431
Gualda, E., Estebanez, P. P., & Faroldi, L. G. (2026) · Redes Revista hispana para el análisis de redes sociales · doi:10.5565/rev/redes.1129 · Cited by 1
Information Cocoon and Citizens' Political Support: Evidence From China
Ding, T., Zhong, Z. T., & Jing, H. (2025) · International Journal of Public Opinion Research · doi:10.1093/ijpor/edaf069
Zhu, Y. E., Leiner, D. J., Neuendorf, N. L., & Scherr, S. (2025) · Human Communication Research · doi:10.1093/hcr/hqaf031
How Do Competing Narratives Spread? A Stance-Based Epidemiological Approach
Gurung, M. I., & Agarwal, N. (2026) · Lecture notes in computer science · doi:10.1007/978-3-032-14107-1_8
Engaging to Oppose: Cross-Cutting Patterns in Hostile News Commentary
Noh, S. Y., & Soroka, S. (2026) · The International Journal of Press/Politics · doi:10.1177/19401612261416569
Gamez-Djokic, M., Mooijman, M., Rocklage, M. D., & Kouchaki, M. (2026) · Journal of Experimental Social Psychology · doi:10.1016/j.jesp.2026.104893 · Cited by 1
A Machine Learning Driven Framework for Enhancing Digital Election Campaigns to Strengthen Democracy
V., M. B. Y., Naidu, P. A. S., & Prof. Deepak, B. (2026) · Vidhyayana · doi:10.58213/b8wxac09
Nagura, T., & Akiyama, E. (2025) · IEEE International Conference on Big Data (BigData) · doi:10.1109/bigdata66926.2025.11402391
Lev‐On, A. (2026) · Information Communication & Society · doi:10.1080/1369118x.2026.2641632
Kermani, H. (2026) · Journal of Information Technology & Politics · doi:10.1080/19331681.2026.2645613
The social dilemma of online segregation: A dynamical model of platform choice
Banisch, S., Jacob, D., Willaert, T., & Olbrich, E. (2026) · Rationality and Society · doi:10.1177/10434631261428850 · Cited by 2
Zhu, Z., Chen, F., & Jin, Y. (2026) · Transportation Research Part F Traffic Psychology and Behaviour · doi:10.1016/j.trf.2026.103596
Zhang, S., Yao, X., & Yu, X. (2026) · Psychology and Sexuality · doi:10.1080/19419899.2026.2647295
Competing Narratives on TikTok: Modeling Taiwan’s 2024 Election Dynamics
Gurung, M. I., & Agarwal, N. (2026) · Studies in computational intelligence · doi:10.1007/978-3-032-16645-6_26
Valdez, J. E. P. (2022) · theses.fr (ABES) · doi:10.70675/9d59d434z27f3z480fzbdd5ze6a4ffb83cec
Happtitude in Action: Emotional Engagement and the Digital Transformation of Political Communication
Verma, S., Bhalla, P., Zafar, S., Kamboj, B., & Monga, S. (2026) · Emerald Group Publishing Limited eBooks · doi:10.1108/978-1-83708-712-920261006
Hwang, T., & Shin, S. (2026) · Social Sciences · doi:10.3390/socsci15040241
Topic Matters: How Linguistic Properties can Shape Reading Behaviour in Selective Exposure Studies
Krämer, T., Kern, D., Kosch, T., & Hienert, D. (2026) · CHI Conference Extended Abstracts on Human Factors in Computing Systems (CHI EA) · doi:10.1145/3772363.3799294
Reframing Social Psychology for the Virtual Age
Bajwa, R. S., & Yunus, A. (2026) · IGI Global eBooks · doi:10.4018/979-8-3373-5896-3.ch001
Metadata
- Authors
- Garrett, R. K.
- Affiliations
- The Ohio State University (US)
- Corresponding author
- Garrett, R. Kelly
- ORCID
- Garrett, R. Kelly
- Venue
- Journal of Computer-Mediated Communication
- Publisher
- Oxford University Press (OUP)
- Published
- 2009-01
- Volume
- 14
- Issue
- 2
- Pages
- 265-285
- ISSN
- 1083-6101 (ISSN-L)
- OpenAlex
- W2137809006
- Cited by
- 1,040
- References
- 27
- Citations by year
- 2026: 64 · 2025: 86 · 2024: 89 · 2023: 89 · 2022: 104 · 2021: 102 · 2020: 120 · 2019: 93 · 2018: 62 · 2017: 50 · 2016: 38 · 2015: 33 · 2014: 29 · 2013: 38 · 2012: 16
- FWCI
- 45.29
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Journal of Computer-Mediated Communication (publishedVersion)
- Topics
- Social Sciences › Sociology and Political Science › Media Influence and Politics
- Social Sciences › Communication › Social Media and Politics
- Social Sciences › Communication › News Media Framing and Political Communication
- Keywords
- selective exposure, echo chambers, online news, political information, political polarization, news avoidance
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
Are you an author, or do you see a problem with this page? Request a review
