{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,10]],"date-time":"2026-10-10T02:08:32Z","timestamp":1791598112809,"version":"4.3.4"},"reference-count":53,"publisher":"Public Library of Science (PLoS)","issue":"8","license":[{"start":{"date-parts":[[2025,8,8]],"date-time":"2025-08-08T00:00:00Z","timestamp":1754611200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["JP23K25160"],"award-info":[{"award-number":["JP23K25160"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["JP23K25160"],"award-info":[{"award-number":["JP23K25160"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["JP21KK0027"],"award-info":[{"award-number":["JP21KK0027"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["JP21KK0027"],"award-info":[{"award-number":["JP21KK0027"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["JP21KK0027"],"award-info":[{"award-number":["JP21KK0027"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:p>Humans have achieved widespread cooperation, largely sustained by mechanisms such as indirect reciprocity, which relies on reputation and social norms. People are highly motivated to maintain a good reputation, and social norms play a critical role in reputation systems by defining acceptable behavior, helping prevent exploitation by free-riders. However, there is a gap between theory and experiment in handling reputation information, with experiments often failing to capture the complexity that theoretical models propose. Here, we address two key issues: what kind of information is needed to define reputation as a social norm and the appropriate level of granularity required for reputation information to function effectively. This paper combines scenario-based experiments and evolutionary game theory to investigate the social norms individuals adopt in real-world settings, aiming to uncover the stability of these norms. Our results show that reputations should be categorized into three levels good, neutral, and bad. Results suggest gradual reputation dynamics that increase and decrease gradually due to cooperation or defection. However, a person\u2019s reputation remains unchanged only when they defect against a bad reputation. Our experimental and theoretical results support critical insights into the dynamics of reputation and social norms within indirect reciprocity, challenging traditional binary reputational evaluations. The gradual nature of reputation updating and the use of nuanced evaluations provide a more realistic model of reputation dynamics.<\/jats:p>","DOI":"10.1371\/journal.pone.0329742","type":"journal-article","created":{"date-parts":[[2025,8,8]],"date-time":"2025-08-08T17:30:26Z","timestamp":1754674226000},"page":"e0329742","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":2,"title":["Gradual reputation dynamics evolve and sustain cooperation in indirect reciprocity"],"prefix":"10.1371","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7966-2629","authenticated-orcid":true,"given":"Hitoshi","family":"Yamamoto","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9943-2668","authenticated-orcid":true,"given":"Isamu","family":"Okada","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Takahisa","family":"Suzuki","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2025,8,8]]},"reference":[{"issue":"1753","key":"pone.0329742.ref001","first-page":"20122573","article-title":"Food sharing in vampire bats: reciprocal help predicts donations more than relatedness or harassment","volume":"280","author":"GG Carter","year":"2013","journal-title":"Proc Biol Sci."},{"issue":"2","key":"pone.0329742.ref002","doi-asserted-by":"crossref","first-page":"20140959","DOI":"10.1098\/rsbl.2014.0959","article-title":"Norway rats reciprocate help according to the quality of help they received","volume":"11","author":"V Dolivo","year":"2015","journal-title":"Biology Letters."},{"key":"pone.0329742.ref003","unstructured":"Nowak M, Highfield R. Supercooperators: Altruism, evolution, and why we need each other to succeed. Simon and Schuster; 2012."},{"issue":"5805","key":"pone.0329742.ref004","doi-asserted-by":"crossref","first-page":"1560","DOI":"10.1126\/science.1133755","article-title":"Five rules for the evolution of cooperation","volume":"314","author":"MA Nowak","year":"2006","journal-title":"Science."},{"key":"pone.0329742.ref005","volume-title":"The economics of rights, cooperation and welfare","author":"R Sugden","year":"1986"},{"key":"pone.0329742.ref006","volume-title":"The biology of moral systems","author":"R Alexander","year":"1987"},{"issue":"6685","key":"pone.0329742.ref007","doi-asserted-by":"crossref","first-page":"573","DOI":"10.1038\/31225","article-title":"Evolution of indirect reciprocity by image scoring","volume":"393","author":"MA Nowak","year":"1998","journal-title":"Nature."},{"issue":"4","key":"pone.0329742.ref008","doi-asserted-by":"crossref","first-page":"561","DOI":"10.1006\/jtbi.1998.0775","article-title":"The dynamics of indirect reciprocity","volume":"194","author":"MA Nowak","year":"1998","journal-title":"J Theor Biol."},{"issue":"1","key":"pone.0329742.ref009","doi-asserted-by":"crossref","first-page":"63","DOI":"10.2307\/2297925","article-title":"Social norms and community enforcement","volume":"59","author":"M Kandori","year":"1992","journal-title":"Rev Econ Stud."},{"issue":"12","key":"pone.0329742.ref010","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pcbi.0020178","article-title":"Stern-judging: A simple, successful norm which promotes cooperation under indirect reciprocity","volume":"2","author":"JM Pacheco","year":"2006","journal-title":"PLoS Comput Biol."},{"issue":"1","key":"pone.0329742.ref011","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pcbi.1004709","article-title":"Social norms of cooperation in small-scale societies","volume":"12","author":"FP Santos","year":"2016","journal-title":"PLoS Comput Biol."},{"issue":"7695","key":"pone.0329742.ref012","doi-asserted-by":"crossref","first-page":"242","DOI":"10.1038\/nature25763","article-title":"Social norm complexity and past reputations in the evolution of cooperation","volume":"555","author":"FP Santos","year":"2018","journal-title":"Nature."},{"issue":"1468","key":"pone.0329742.ref013","doi-asserted-by":"crossref","first-page":"745","DOI":"10.1098\/rspb.2000.1573","article-title":"Evolution of cooperation through indirect reciprocity","volume":"268","author":"O Leimar","year":"2001","journal-title":"Proc Biol Sci."},{"issue":"1","key":"pone.0329742.ref014","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1016\/S0022-5193(03)00154-1","article-title":"A tale of two defectors: the importance of standing for evolution of indirect reciprocity","volume":"224","author":"K Panchanathan","year":"2003","journal-title":"J Theor Biol."},{"issue":"4","key":"pone.0329742.ref015","doi-asserted-by":"crossref","first-page":"435","DOI":"10.1016\/j.jtbi.2005.08.008","article-title":"The leading eight: social norms that can maintain cooperation by indirect reciprocity","volume":"239","author":"H Ohtsuki","year":"2006","journal-title":"Journal of Theoretical Biology."},{"issue":"3","key":"pone.0329742.ref016","doi-asserted-by":"crossref","first-page":"518","DOI":"10.1016\/j.jtbi.2006.08.018","article-title":"Global analyses of evolutionary dynamics and exhaustive search for social norms that maintain cooperation by reputation","volume":"244","author":"H Ohtsuki","year":"2007","journal-title":"J Theor Biol."},{"key":"pone.0329742.ref017","doi-asserted-by":"crossref","DOI":"10.3389\/fphy.2018.00014","article-title":"A theoretical approach to norm ecosystems: two adaptive architectures of indirect reciprocity show different paths to the evolution of cooperation","volume":"6","author":"S Uchida","year":"2018","journal-title":"Front Phys."},{"issue":"1484","key":"pone.0329742.ref018","doi-asserted-by":"crossref","first-page":"2495","DOI":"10.1098\/rspb.2001.1809","article-title":"Cooperation through indirect reciprocity: image scoring or standing strategy?","volume":"268","author":"M Milinski","year":"2001","journal-title":"Proc Biol Sci."},{"issue":"3","key":"pone.0329742.ref019","doi-asserted-by":"crossref","first-page":"230","DOI":"10.1016\/j.evolhumbehav.2015.12.001","article-title":"Reputation-based cooperation: empirical evidence for behavioral strategies","volume":"37","author":"V Swakman","year":"2016","journal-title":"Evol Hum Behav."},{"issue":"1","key":"pone.0329742.ref020","doi-asserted-by":"crossref","first-page":"14813","DOI":"10.1038\/s41598-018-33147-x","article-title":"Experimental evidence of selective inattention in reputation-based cooperation","volume":"8","author":"I Okada","year":"2018","journal-title":"Sci Rep."},{"issue":"6","key":"pone.0329742.ref021","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pone.0235137","article-title":"Justified defection is neither justified nor unjustified in indirect reciprocity","volume":"15","author":"H Yamamoto","year":"2020","journal-title":"PLoS One."},{"issue":"5467","key":"pone.0329742.ref022","doi-asserted-by":"crossref","first-page":"850","DOI":"10.1126\/science.288.5467.850","article-title":"Cooperation through image scoring in humans","volume":"288","author":"C Wedekind","year":"2000","journal-title":"Science."},{"issue":"6870","key":"pone.0329742.ref023","doi-asserted-by":"crossref","first-page":"424","DOI":"10.1038\/415424a","article-title":"Reputation helps solve the \u201ctragedy of the commons\u201d","volume":"415","author":"M Milinski","year":"2002","journal-title":"Nature."},{"issue":"8","key":"pone.0329742.ref024","doi-asserted-by":"crossref","first-page":"1457","DOI":"10.1016\/j.jpubeco.2004.03.008","article-title":"Cooperation among strangers with limited information about reputation","volume":"89","author":"GE Bolton","year":"2005","journal-title":"Journal of Public Economics."},{"issue":"5960","key":"pone.0329742.ref025","doi-asserted-by":"crossref","first-page":"1701","DOI":"10.1126\/science.1178883","article-title":"Indirect punishment and generosity toward strangers","volume":"326","author":"A Ule","year":"2009","journal-title":"Science."},{"key":"pone.0329742.ref026","doi-asserted-by":"crossref","first-page":"10424","DOI":"10.1073\/pnas.1301210110","article-title":"Powering up with indirect reciprocity in a large-scale field experiment","author":"E Yoeli","year":"2013","journal-title":"Proc Natl Acad Sci U S A."},{"issue":"7","key":"pone.0329742.ref027","doi-asserted-by":"crossref","first-page":"2666","DOI":"10.1073\/pnas.0407370102","article-title":"Indirect reciprocity, image scoring, and moral hazard","volume":"102","author":"H Brandt","year":"2005","journal-title":"Proc Natl Acad Sci U S A."},{"issue":"48","key":"pone.0329742.ref028","doi-asserted-by":"crossref","first-page":"12241","DOI":"10.1073\/pnas.1810565115","article-title":"Indirect reciprocity with private, noisy, and incomplete information","volume":"115","author":"C Hilbe","year":"2018","journal-title":"Proc Natl Acad Sci U S A."},{"issue":"1","key":"pone.0329742.ref029","doi-asserted-by":"crossref","first-page":"16799","DOI":"10.1038\/s41598-020-73564-5","article-title":"Two ways to overcome the three social dilemmas of indirect reciprocity","volume":"10","author":"I Okada","year":"2020","journal-title":"Sci Rep."},{"issue":"1","key":"pone.0329742.ref030","doi-asserted-by":"crossref","first-page":"25073","DOI":"10.1038\/s41598-024-76168-5","article-title":"Clarifying social norms which have robustness against reputation costs and defector invasion in indirect reciprocity","volume":"14","author":"H Yamamoto","year":"2024","journal-title":"Sci Rep."},{"key":"pone.0329742.ref031","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1016\/j.geb.2016.05.003","article-title":"On the stability of cooperation under indirect reciprocity with first-order information","volume":"98","author":"U Berger","year":"2016","journal-title":"Games and Economic Behavior."},{"issue":"20","key":"pone.0329742.ref032","doi-asserted-by":"crossref","DOI":"10.1073\/pnas.2300544120","article-title":"Evolutionary stability of cooperation in indirect reciprocity under noisy and private assessment","volume":"120","author":"Y Fujimoto","year":"2023","journal-title":"Proc Natl Acad Sci U S A."},{"issue":"2","key":"pone.0329742.ref033","doi-asserted-by":"crossref","DOI":"10.1103\/PRXLife.2.023009","article-title":"Who is a Leader in the leading eight? indirect reciprocity under private assessment","volume":"2","author":"Y Fujimoto","year":"2024","journal-title":"PRX Life."},{"issue":"33","key":"pone.0329742.ref034","doi-asserted-by":"crossref","DOI":"10.1073\/pnas.2406885121","article-title":"Computational evolution of social norms in well-mixed and group-structured populations","volume":"121","author":"Y Murase","year":"2024","journal-title":"Proc Natl Acad Sci U S A."},{"issue":"11","key":"pone.0329742.ref035","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pcbi.1004527","article-title":"Reputation effects in public and private interactions","volume":"11","author":"H Ohtsuki","year":"2015","journal-title":"PLoS Comput Biol."},{"key":"pone.0329742.ref036","doi-asserted-by":"crossref","DOI":"10.1017\/CBO9781139173179","volume-title":"Evolutionary games and population dynamics","author":"J Hofbauer","year":"1998"},{"issue":"1","key":"pone.0329742.ref037","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1145\/2414425.2414442","article-title":"Mathematical description and analysis of adaptive risk choice behavior","volume":"4","author":"I Okada","year":"2013","journal-title":"ACM Trans Intell Syst Technol."},{"issue":"5","key":"pone.0329742.ref038","doi-asserted-by":"crossref","first-page":"604","DOI":"10.1177\/1948550617720271","article-title":"Death before dishonor","volume":"9","author":"AJ Vonasch","year":"2017","journal-title":"Social Psychological and Personality Science."},{"issue":"3","key":"pone.0329742.ref039","doi-asserted-by":"crossref","first-page":"231","DOI":"10.1007\/BF02912493","article-title":"Human conversational behavior","volume":"8","author":"RI Dunbar","year":"1997","journal-title":"Hum Nat."},{"issue":"2","key":"pone.0329742.ref040","doi-asserted-by":"crossref","first-page":"185","DOI":"10.1177\/1948550619837000","article-title":"Who gossips and how in everyday life?","volume":"11","author":"ML Robbins","year":"2019","journal-title":"Social Psychological and Personality Science."},{"key":"pone.0329742.ref041","doi-asserted-by":"crossref","first-page":"338","DOI":"10.1016\/j.jtbi.2012.10.031","article-title":"Indirect reciprocity with trinary reputations","volume":"317","author":"S Tanabe","year":"2013","journal-title":"J Theor Biol."},{"issue":"1","key":"pone.0329742.ref042","doi-asserted-by":"crossref","first-page":"455","DOI":"10.1038\/s41598-021-04033-w","article-title":"Social norms in indirect reciprocity with ternary reputations","volume":"12","author":"Y Murase","year":"2022","journal-title":"Sci Rep."},{"key":"pone.0329742.ref043","doi-asserted-by":"crossref","first-page":"41870","DOI":"10.1038\/srep41870","article-title":"The evolution of conditional moral assessment in indirect reciprocity","volume":"7","author":"T Sasaki","year":"2017","journal-title":"Sci Rep."},{"issue":"6868","key":"pone.0329742.ref044","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1038\/415137a","article-title":"Altruistic punishment in humans","volume":"415","author":"E Fehr","year":"2002","journal-title":"Nature."},{"issue":"4","key":"pone.0329742.ref045","doi-asserted-by":"crossref","first-page":"671","DOI":"10.1111\/j.1465-7295.2007.00051.x","article-title":"The effect of rewards and sanctions in provision of public goods","volume":"45","author":"M Sefton","year":"2007","journal-title":"Economic Inquiry."},{"issue":"50","key":"pone.0329742.ref046","doi-asserted-by":"crossref","first-page":"19931","DOI":"10.1073\/pnas.1110306108","article-title":"How infants and toddlers react to antisocial others","volume":"108","author":"JK Hamlin","year":"2011","journal-title":"Proc Natl Acad Sci U S A."},{"issue":"1","key":"pone.0329742.ref047","doi-asserted-by":"crossref","first-page":"3339","DOI":"10.1038\/s41598-025-87170-w","article-title":"Exploring condition in which people accept AI over human judgements on justified defection","volume":"15","author":"H Yamamoto","year":"2025","journal-title":"Sci Rep."},{"issue":"4","key":"pone.0329742.ref048","doi-asserted-by":"crossref","first-page":"826","DOI":"10.1037\/a0011381","article-title":"Cooperation in social dilemmas: free riding may be thwarted by second-order reward rather than by punishment","volume":"95","author":"T Kiyonari","year":"2008","journal-title":"J Pers Soc Psychol."},{"issue":"2","key":"pone.0329742.ref049","doi-asserted-by":"crossref","first-page":"21","DOI":"10.5178\/lebs.2012.22","article-title":"Reputational benefit of punishment: comparison among the punisher, rewarder, and non-sanctioner","volume":"3","author":"H Ozono","year":"2012","journal-title":"Letters on Evolutionary Behavioral Science."},{"issue":"2","key":"pone.0329742.ref050","doi-asserted-by":"crossref","first-page":"98","DOI":"10.1016\/j.tree.2014.12.003","article-title":"The reputation of punishers","volume":"30","author":"NJ Raihani","year":"2015","journal-title":"Trends Ecol Evol."},{"issue":"1","key":"pone.0329742.ref051","doi-asserted-by":"crossref","first-page":"6","DOI":"10.5178\/lebs.2020.72","article-title":"The evaluation of second- and third-party punishers","volume":"11","author":"N Mifune","year":"2020","journal-title":"Lett Evol Behav Sci."},{"key":"pone.0329742.ref052","doi-asserted-by":"crossref","first-page":"1198797","DOI":"10.3389\/fpsyg.2023.1198797","article-title":"Punishment in the public goods game is evaluated negatively irrespective of non-cooperators\u2019 motivation","volume":"14","author":"Y Li","year":"2023","journal-title":"Front Psychol."},{"issue":"3","key":"pone.0329742.ref053","doi-asserted-by":"crossref","first-page":"428","DOI":"10.1177\/0022022109359692","article-title":"Indecisiveness and culture: incidence, values, and thoroughness","volume":"41","author":"JF Yates","year":"2010","journal-title":"Journal of Cross-Cultural Psychology."}],"container-title":["PLOS One"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0329742","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,8,8]],"date-time":"2025-08-08T17:30:33Z","timestamp":1754674233000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0329742"}},"subtitle":[],"editor":[{"given":"The Anh","family":"Han","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"editor"}]}],"short-title":[],"issued":{"date-parts":[[2025,8,8]]},"references-count":53,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2025,8,8]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0329742","relation":{},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,8,8]]}}}