Kamei, Kenju

写真a

Affiliation

Faculty of Economics ( Mita )

Position

Professor

Related Websites
Scopus Paper Info  
Paper Count: 33 Citation Count: 395 h-index: 9

Click to view the Scopus page. The data was downloaded from Scopus API in April 19, 2026, via http://api.elsevier.com and http://www.scopus.com .

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Profile 【 Display / hide 】

  • 私の専門は、経済実験を通じて行動データを収集し、経済仮説を検証する研究分野であり、応用経済学のさまざまな問題を対象に研究を行っています。具体的には、組織・社会における民主的意思決定、ワークプレイス・デモクラシーや労働者の生産性、モラルハザードやサボタージュなどのビジネス経済学のテーマ、ピア効果など教育・労働経済学のトピックス、人々の投票行動や制度構築に関する組織・政治経済学のトピックス、オンライン・メカニズムの効果や評判形成を含むユーザの行動特性、社会的ジレンマ下での人々の協力行動に関する行動経済学的研究、人々の利他的な罰則行動など幅広い分野で研究活動を進めています。

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Message from the Faculty Member 【 Display / hide 】

  • 人間を対象とする現実の社会では、経済理論の通りに物事が進まないことも少なくありません。そのため、経済実験などを通じて、日々さまざまな発見があります。皆さんも経済学を学ぶ際には、経済学の前提や設定、各専門領域の理論的示唆が、現実の社会の事象にどの程度当てはまるのかを考えてみてください。もし当てはまるのであればなぜなのか、当てはまらないのであればどの前提が妥当でないのか、といった点を人々の行動原理から考えることで、多くの発見があり、経済学がより面白く感じられると思います。

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Academic Background 【 Display / hide 】

  • 1996.04
    -
    2000.03

    The University of Tokyo, Engineering, Civil Engineering

    University, Graduated

  • 2000.04
    -
    2002.03

    The University of Tokyo, Engineering, Civil Engineering

    Graduate School, Completed, Master's course

  • 2006.09
    -
    2007.05

    Brown University, Department of Economics

    United States, Graduate School, Master's course

  • 2006.09
    -
    2011.05

    Brown University, Department of Economics

    United States, Graduate School, Completed, Doctoral course

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Books 【 Display / hide 】

  • はじめての実験経済学ーやさしくわかる意思決定の特徴

    亀井　憲樹, オーム社, 2024.12,  Page： 324

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Papers 【 Display / hide 】

  • Motivations behind peer-to-peer (Counter-)punishment in public goods games: An experiment

    Kamei K., Tabero K.

    Economics Letters 257 2025.12

    ISSN  01651765

    　View Summary

    It is well-known that efficiency often fails to improve in public goods games with peer-to-peer punishment when counter-punishment is possible. This paper experimentally demonstrates, for the first time, that the effects of sanctioning institutions are modest, regardless of the decision-making format (individual or team). In the “team” conditions, subjects are randomly assigned to teams of three, and make joint decisions through communication. Their dialogue provides valuable insights into the motivations behind (counter-)punishment, as well as the resulting behavioral effects. A coding exercise reveals that first-order punishments (and counter-punishments) are primarily emotional responses to peers’ low contributions (and first-order punishments, respectively).

  • Collective sanction enforcement: New experimental evidence from two societies

    Kamei K., Sharma S., Walker M.J.

    Journal of Economic Behavior and Organization 237 2025.09

    ISSN  01672681

    　View Summary

    This paper presents the first experimental study on how higher-order punishment affects third-party sanction enforcement in the presence of multiple third parties. The design varies across treatments the number of third parties witnessing a norm violation and the opportunities available for third parties to costly punish each other after observing their peers’ enforcement actions. To test generalizability of higher-order enforcement effects, the experiment is conducted across two contrasting societies – India and the United Kingdom – using a prisoner's dilemma game. These societies are selected for their positions at opposite ends of the tight-loose ancestral kinship spectrum. In both societies, third parties punish defectors who exploit their paired cooperators more strongly than any other person, consistent with prior research. Yet, punitive patterns differ. In the UK, third parties punish defectors less frequently and less strongly when other third parties are present; when higher-order punishments are available among third parties, their failure to punish defectors and acts of anti-social punishment invite strong higher-order punishment from their peers, which encourages their pro-social first-order punishments and makes mutual cooperation a Nash equilibrium outcome in the primary cooperation dilemma. However, in India, overall punishment levels are lower, group size and incentive structure changes have no discernible effects, and higher-order punishments are not better disciplined. These findings support a model of norm conformity for the UK and do not contradict such a model for India.

  • Free riding, democracy, and sacrifice in the workplace: Evidence from a real-effort experiment

    Kamei K., Tabero K.

    Journal of Economics and Management Strategy 34 ( 1 ) 3 - 23 2025.02

    ISSN  10586407

    　View Summary

    Teams are increasingly popular decision-making and work units in firms. This paper uses a novel real-effort experiment to show that (a) some teams in the workplace reduce their members' private benefits to achieve a group optimum in a social dilemma and (b) such endogenous choices by themselves enhance their work productivity (per-work-time production)—a phenomenon called the “dividend of democracy.” In the experiment, worker subjects are randomly assigned to a team of three, and they then jointly solve a collaborative real-effort task under a revenue-sharing rule in their group with two other teams, while each individual worker can privately and independently shirk by playing a Tetris game. Strikingly, teams exhibit significantly higher productivity (per-work-time production) when they can decide whether to reduce the return from shirking by voting than when the policy implementation is randomly decided from above, irrespective of the policy implementation outcome. This means that democratic culture directly affects behavior. On the other hand, the workers under democracy also increase their shirking, presumably due to enhanced fatigue owing to the stronger productivity. Despite this, democracy does not decrease overall production thanks to the enhanced work productivity.

  • Endogenous monitoring through voluntary reporting in an infinitely repeated prisoner's dilemma game: experimental evidence

    Kamei K., Nesterov A.

    Economica 91 ( 364 ) 1553 - 1577 2024.10

    ISSN  00130427

    　View Summary

    Exogenous reputational information is known to improve cooperation. This study experimentally investigates how people create such information by reporting their partner's action choices, and whether endogenous monitoring helps to sustain cooperation, in an indefinitely repeated prisoner's dilemma game with random matching. The experimental results show that most subjects report their opponents' action choices, thereby successfully cooperating when reporting does not involve costs. However, when reporting is costly, participants are strongly discouraged from doing so. Consequently, they fail to achieve strong cooperative norms when the reported information is conveyed privately only to their next-round interaction partners. Costly reporting occurs only occasionally even when there is a public record whereby all future partners can check the reported information, but significantly more frequently relative to the condition in which it is sent to the next partner only. With public records, groups can foster cooperative norms aided by reported information that gradually accumulates and becomes more informative over time.

  • Self-regulatory resources and institutional formation: An experiment

    Kamei K.

    Journal of Economic Behavior and Organization 222   354 - 374 2024.06

    ISSN  01672681

    　View Summary

    A novel laboratory experiment is used to show that the state of people's self-regulatory resources influences their reliance on the formal enforcement of norms in a social dilemma. The subjects’ self-regulatory resources are manipulated using well-known depletion tasks. On the one hand, when their resources are not depleted, most decide to govern themselves through decentralized, peer-to-peer punishment in a public goods dilemma, and then achieve high cooperation norms. On the other hand, when the resources are limited, the majority enact a costly formal sanctioning institution; backed by formal punishment, the groups achieve strong cooperation. A supplementary survey on the Covid-19 pandemic was conducted to enhance the external validity of the findings, generating a similar pattern while revealing that people's desire to commit, not their beliefs about others’ behavior without formal enforcement, drives their institutional preferences. Self-control preference theories, combined with inequity aversion, can explain these patterns because they predict that those with limited self-control are motivated to remove temptations in advance as a commitment device.

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Papers, etc., Registered in KOARA 【 Display / hide 】

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

  • Productivity, norms, and efficiency in Japanese organizations: An experimental investigation

    2025.06
    -
    2029.03

    挑戦的研究（開拓）, Principal investigator

  • Efficient institutions to overcome social dilemmas

    2023.04
    -
    2027.03

    基盤研究(B), Principal investigator

  • Task-preference matching and worker behavior

    2022.08
    -
    2024.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, 研究活動スタート支援, Principal investigator

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Courses Taught 【 Display / hide 】

  • RESEARCH SEMINAR (THESIS)

    2026

  • BUSINESS ECONOMICS

    2026

  • EXPERIMENTAL ECONOMICS

    2026

  • RESEARCH SEMINAR C

    2026

  • RESEARCH SEMINAR IN EXPERIMENTAL ECONOMICS

    2026

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