Specific Lines of Research

I primarily use experimental games from experimental economics to investigate the following areas. In addition, I supplement some of them with mathematical models from evolutionary game theory. Within the broad topic of cooperation, I am currently pursuing the following non-mutually exclusive lines of research:

1) BIOLOGICAL MARKETS, PARTNER CHOICE, AND COMPETITIVE HELPING: When organisms can choose whom they interact with, this partner choice creates a “biological market” where individuals must compete with each other over partnerships. My work applies this concept to human partnerships (e.g., friends, allies, coalition members, mates) to understand how people choose and get chosen by partners. Many of the traits that we value in partners are cues of someone’s value as a partner (ability, willingness, and availability to help). One confirmed prediction is that people will compete by being more generous than others (“competitive altruism” or “competitive helping”).

Barclay, P., & Barker, J. (2020). Greener than thou: people who protect the environment are more cooperative, compete to be environmental, and benefit from reputation. Journal of Environmental Psychology, 72, 101441. [LINK]

*Pleasant, A., & Barclay, P. (2018). Why hate the good guy? Antisocial punishment of high cooperators is higher when people compete to be chosen. Psychological Science, 29, 868-876. [LINK] [PDF]

Barclay, P. (2017). Attractiveness biases are the tip of the iceberg in biological markets – a commentary on Maestripieri et al. Behavioral and Brain Sciences, 40, 17-18. [LINK] [PDF]

Arnocky, S., Piché, T., Albert, G., Ouellette, D., & Barclay, P. (2017). Altruism predicts mating success in humans. British Journal of Psychology, 108, 416-435. [LINK] [PDF]

Raihani, N., & Barclay, P. (2016). Exploring the trade-off between quality and fairness in human partner choice. Royal Society Open Science, 3, 160510. [LINK] [PDF]

Barclay, P., & Raihani, N. (2016). Partner choice versus punishment in human prisoner’s dilemmas. Evolution and Human Behavior, 37, 263-271. [LINK] [PDF]

Barclay, P. (2016). Biological markets and the effects of partner choice on cooperation and friendship. Current Opinion in Psychology, 7, 33-38. [LINK] [PDF]

Barclay, P. (2013). Strategies for cooperation in biological markets, especially for humans. Evolution & Human Behavior, 34(3), 164-175. [LINK] [PDF]

Barclay, P. (2011). Competitive helping increases with the size of biological markets and invades defection. Journal of Theoretical Biology, 281, 47-55. [LINK] [PDF]

Barclay, P. (2010). Altruism as a courtship display: Some effects of third-party generosity on audience perceptions. British Journal of Psychology, 101, 123-135. [LINK] [PDF]

Barclay, P., & Willer, R. (2007). Partner choice creates competitive altruism in humans. Proceedings of the Royal Society of London Series B, 274, 749-753. [LINK] [PDF]

­­­­­­­Barclay, P. (2004). Trustworthiness and Competitive Altruism Can Also Solve the “Tragedy of the Commons”. Evolution & Human Behavior, 25(4), 209-220. [LINK] [PDF]

2) REPUTATIONAL BENEFITS FOR COOPERATIVE BEHAVIOUR: if cooperators receive private benefits for their actions, however unintended those benefits are, then this can cause natural selection and/or learning of cooperative sentiment. There is much overlap between this topic and biological markets – here are the papers on reputational benefits which are not specifically related to biological markets.

*Rotella, A., Sparks, A.M., & Barclay, P. (2020). Feelings of obligation are valuations of signaling-mediated social payoffs. Behavioral and Brain Sciences, 43, e85.

*Sparks, A., Burleigh, T., & Barclay, P. (2016). We can see inside: accurate predictions of Prisoner’s Dilemma decisions after a brief face-to-face interaction. Evolution and Human Behavior210-216[LINK] [PDF]

Barclay, P. (2015). Reputation. In D. Buss (Ed.) Handbook of Evolutionary Psychology (2nd Ed.), pp. 810-828. Hoboken, NJ: J. Wiley & Sons. [PDF]

*Sparks, A., & Barclay, P. (2015). No effect on condemnation of short or long exposure to eye images. Letters on Evolutionary Behavioral Science, 6, 13-16. [LINK] [PDF]

*Sparks, A., & Barclay, P. (2013). Eyes increase generosity, but not for long: the limited effect of a false cue. Evolution & Human Behavior, 34, 317-322. [LINK] [PDF]

Barclay, P. (2012). Harnessing the power of reputation: strengths and limits for promoting cooperative behaviours. Evolutionary Psychology, 10(5), 868-883. [LINK] [PDF]

Barclay, P., & Reeve, H.K. (2012). The varying relationship between helping and individual quality. Behavioral Ecology, 23(4), 693-698. [LINK] [PDF]

3) COSTLY PUNISHMENT: people are willing to incur costs to punish others who don’t cooperate, and cooperation is much higher when punishment is present. But why are people willing to punish, if doing so is costly and if all group members (including non-punishers) benefit from the resulting increase in cooperation? My research to date has investigated reputational benefits for punitive behaviour including deterrence and trust, and the prevalence or lack thereof of second-order punishment (punishing those who don’t punish free-riders).

*Pleasant, A., & Barclay, P. (2018). Why hate the good guy? Antisocial punishment of high cooperators is higher when people compete to be chosen. Psychological Science, 29, 868-878. [LINK] [PDF]

Barclay, P., & Raihani, N. (2016). Partner choice versus punishment in human prisoner’s dilemmas. Evolution and Human Behavior37, 263-271. [LINK] [PDF]

Barclay, P., & Kiyonari, T. (2014). Why sanction? Functional causes of punishment and reward. In P. Van Lange, B. Rockenbach, & T. Yamagishi (Eds.) Social Dilemmas: New Perspectives on Reward and Punishment, pp. 182-196. Oxford, UK: Oxford University Press. [PDF]

Barclay, P. (2012). Proximate and ultimate causes of Strong Reciprocity and punishment. Behavioral and Brain Sciences, 35(1), 16-17. [PDF]

Kiyonari, T., & Barclay, P. (2008). Cooperation in social dilemmas: free-riding may be thwarted by second-order rewards rather than punishment. Journal of Personality and Social Psychology, 95(4), 826-842. [LINK] [PDF]

Barclay, P. (2006). Reputational benefits for altruistic punishment. Evolution and Human Behavior, 27, 325-344. [LINK] [PDF]

4) SCALE OF COMPETITION: In some situations, organisms are in heavy competition with whoever they interact with (local competition). In other situations, any two interaction partners are not in direct competition with each other, but instead compete against the wider population (global competition). This “scale of competition” creates incentives for spite, inequity aversion, and aggression, while simultaneously suppressing cooperation; after all, an organism will do poorly if it helps its direct competitor. I have investigated how the scale of competition affects people’s tolerance for inequality, their willingness to harm others, and their cooperation within classrooms.

Ho, J.L., Powell, D. M., Barclay, P., & Gill, H. (2019). The influence of competition on motivation to fake in employment interviews. Journal of Personnel Psychology, 18(2), 95-105. [LINK] [PDF]

Barker, J., & Barclay, P. (2016). Local competition increases people’s willingness to harm others. Evolution and Human Behavior315-322. [LINK] [PDF]

Barclay, P., & Stoller, B. (2014). Local competition sparks concern for fairness in the ultimatum game. Biology Letters, 10, 20140213. [LINK] [PDF]

Krupp, D. B., Kim, J., Taylor, P., & Barclay, P. (2014). Cooperation and competition in large classrooms. Toronto: Higher Education Quality Council of Ontario. [PDF]

5) COGNITIVE MECHANISMS UNDERLYING COOPERATIVE EXCHANGE: how specific are these cognitive mechanisms, what other mechanisms are involved in social exchange, and what algorithms do they use? I have tested predictions about the specificity/generality of these cognitive mechanisms, including examining claims that humans possess mental algorithms specifically designed for dealing with people who “cheat” in social contracts.

*Rotella, A., & Barclay, P. (2020). Failure to replicate moral licensing and moral cleansing in an online experiment. Personality and Individual Differences, 161, 109967. [LINK]

Lightner, A.D., Barclay, P., & Hagen, E.H. (2017). Radical framing effects in the ultimatum game: the impact of explicit culturally transmitted frames on economic decision making. Royal Society Open Science, 4, 170453. [LINK] [PDF]

Driscoll, R. L., Barclay, P., & Fenske, M. (2017). To be spurned no more: the affective and behavioural consequences of social and non-social rejection. Psychonomic Bulletin & Review, 24, 566-573. [LINK] [PDF]

Barclay, P. (2008). Enhanced recognition of defectors depends on their rarity. Cognition, 107, 817-828. [LINK] [PDF]

Barclay, P., & Lalumière, M. (2006). Do people differentially remember cheaters? Human Nature, 17(1), 98-113. [LINK] [PDF]

6) INTERGROUP COMPETITION & GROUP THREATS: many theories predict that intragroup cooperation increases in the face of group threat. I have recently done work that empirically demonstrates this “stability-dependent cooperation” and shows how people (especially those of high status) will manipulate that to their own advantage.

Barclay, P., & Benard, S. (2020). The effects of social versus asocial threats on group cooperation and manipulation of perceived threats. Evolutionary Human Sciences, 2, e54. [LINK]

Benard, S., & Barclay, P. (2021). Democratic competition for rank increases both cooperation and deception in small groups. Social Science Quarterly, 101(7), 2413-2436. [LINK]

Barclay, P., & Krupp, D. B. (2016). The burden of proof for a cultural group selection account. Behavioral and Brain Sciences39, 21-22. [PDF]

*Sparks, A., *Mishra, S., & Barclay, P. (2013). Fundamental freedoms and the psychology of threat, bargaining, and inequality. Behavioral and Brain Sciences, 36, 36-37. [PDF]

Barclay, P., & Benard, S. (2013). Who cries wolf, and when: manipulation of perceived threats to preserve rank in cooperative groups. PLOS ONE, 8(9), e73863. doi:10.1371/journal.pone.0073863. [LINK with PDF]

7) MISCELLANEOUS COOPERATION: for topics and publications on cooperation that don’t fit cleanly into any of the above…

Barclay, P. Barclay, P. (2020). Reciprocity creates a stake in one’s partner, or why you should cooperate even when anonymous. Proceedings of the Royal Society of London B, 287, 20200819. [LINK]

*Larney, A., *Rotella, A, & Barclay, P. (2019). Stake size effects in Ultimatum Game and Dictator Game offers: a meta-analysis. Organizational Behavior and Human Decision Processes, 151, 61-72. [LINK] [PDF]

Barclay, P. (2017). Bidding to commit: an experimental test of the benefits of commitment under moderate degrees of conflict. Evolutionary Psychology, 15(1), 1-8. [LINK] [PDF]

Barker, J., Barclay, P., & Reeve, H.K. (2013). Competition over personal resources favors contributions to shared resources in human groups. PLOS ONE, 8(3), e58826. [LINK with PDF]

Barker, J., Barclay, P., & Reeve, H.K. (2012). Within-group competition reduces cooperation and payoffs in human groups. Behavioral Ecology, 23(4), 735-741. [LINK] [PDF]

Krupp, D. B., DeBruine, L. M., & Barclay, P. (2008). A cue of kinship promotes cooperation for the public good. Evolution & Human Behavior, 29, 49-55. [LINK] [PDF]


*Kafashan, S., *Sparks, A., *Rotella, A., & Barclay, P. (2016). Why heroism exists: evolutionary perspectives on extreme helping. In S. T. Allison, G. R. Goethals, & R. M. Kramer (Eds.) The Handbook of Heroism and Heroic Leadership, pp. 36-57. New York, NY: Routledge. [PDF]

Barclay, P. (2015). Reputation. In D. Buss (Ed.) Handbook of Evolutionary Psychology (2nd Ed.), pp. 810-828. Hoboken, NJ: J. Wiley & Sons. [PDF]

Barclay, P., & Van Vugt, M. (2015). The evolutionary psychology of human prosociality: adaptations, mistakes, and byproducts. In D. Schroeder & W. Graziano (Eds.) Oxford Handbook of Prosocial Behavior, pp. 37-60. Oxford, UK: Oxford University Press. [PDF] * Note: most of this chapter was later reused with permission in the authored book “Social Dilemmas: The Psychology of Human Cooperation” by P. Van Lange, D. Balliet, C. D. Parks, & M. Van Vugt, published in 2014 by Oxford University Press. I am first author of the corresponding chapter there.

*Kafashan, S., *Sparks, A., Griskevicius, V., & Barclay, P. (2014). Prosocial behaviour and social status. In J. T. Cheng, J. L. Tracy, & C. Anderson (Eds.) The Psychology of Social Status, pp. 139-158. New York, NY: Springer. [PDF]

Barclay, P. (2012). Harnessing the power of reputation: strengths and limits for promoting cooperative behaviours. Evolutionary Psychology, 10(5), 868-883. [LINK] [PDF]

Barclay, P. (2011). The evolution of charitable behaviour and the power of reputation. In C. Roberts (Ed.) Applied Evolutionary Psychology, pp. 149-172. Oxford, UK: Oxford University Press. [PDF]

Barclay, P. (2010). Reputation and the Evolution of Generous Behavior. Nova Science Publishers, Hauppauge, NY. * Note: this is essentially a very lengthy book chapter based on my PhD thesis introduction & discussion, but the publisher released it as a stand-alone book. [PDF]


*Rotella, A., *Fogg, C., Mishra, S., & Barclay, P. (2019). Measuring delay discounting in a crowdsourced sample: an exploratory study. Scandinavian Journal of Psychology, 60, 520-527. [LINK] [PDF]

Barclay, P., *Mishra, S., & *Sparks, AM. (2018). State-dependent risk-taking. Proceedings of the Royal Society of London B, 285, 20180180. [LINK] [PDF]

*Mishra, S., Barclay, P., & *Sparks, A. (2017). The relative state model: Integrating need-based and ability-based pathways to risk-taking. Personality and Social Psychological Review, 21(2), 176-198. [LINK] [PDF]

*Mishra, S., Barclay, P., & Lalumière, M.L. (2014). Competitive disadvantage facilitates risk taking. Evolution and Human Behavior, 35, 126-132[LINK] [PDF]


*O’Connor, J. J. M., & Barclay, P. (2018). High voice pitch mitigates the aversiveness of antisocial cues in men’s speech. British Journal of Psychology. [LINK] [PDF]

*O’Connor, J., & Barclay, P. (2017). The influence of voice pitch on perceptions of trustworthiness across social contexts. Evolution and Human Behavior, 38(4), 506-512. [LINK] [PDF]

Montano, K.J., Tigue, C.C., Isenstein, S.G.E., Barclay, P., & Feinberg, D. (2017). Men’s voice pitch influences women’s trusting behavior. Evolution and Human Behavior, 38(3), 293-297. [LINK] [PDF]


Karabegović, M., *Rotella, A., & Barclay, P. (2018). Broadening the role of “self-interest” in Folk-Economic Beliefs. Behavioral and Brain Sciences, 41, e174. [LINK]

Tybur, J. M., Inbar, Y., Aarøe, L., Barclay, P., Barlow, F.K., de Barra, M., Becker, D.V., Borovoi, L., Choi, I., Choi, J.A., Consedine, N.S., Conway, A., Conway, J.R., Conway, P., Cubela Adoric, V., Demirci, E., Fernández, A.M., Ferreira, D.C.S., Ishii, K., Jakšić, I., Ji, T., van Leeuwen, L., Lewis, D.M.G., Li, N.P., McIntyre, J.C., Mukherjee, S., Park, J., Pawlowski, B., Petersen, M.B., Pizarro, D., Prodromitis, G., Prokop, P., Rantala, M.J., Reynolds, L.M., Sandin, B., Sevi, B., de Smet, D., Srinivasan, N., Tewari, S., *Wilson, C., Young, J.C., & Žeželj, I. (2016). Parasite stress and pathogen avoidance relate to distinct dimensions of political ideology across 30 nations. Proceedings of the National Academy of Sciences of the USA, 113(44), 12408-12413. [LINK] [PDF]

Driscoll, R. L., Barclay, P., & Fenske, M. (2017). To be spurned no more: The affective and behavioural consequences of social and non-social rejection. Psychonomic Bulletin and Review, 24, 566-573. [LINK] [PDF]

Krupp, D. B., & Barclay, P. (2010). Margo Wilson (1942-2009). Journal of Evolutionary Psychology, 8(1), 1-3. [PDF]

Barclay, P. (2008). Using the hatchet and burying it afterwards – A review of “Beyond revenge: The evolution of the forgiveness instinct”. Invited book review for Evolution & Human Behavior, 29(6), 450-451. [PDF]

Krupp, D.B., Barclay, P., Daly, M., Kiyonari, T., Dingle, G., & Wilson, M. (2005). Let’s add some psychology (and maybe even some evolution) to the mix. Behavioral & Brain Sciences, 28(6), 828-829. [PDF]

Barclay, P., & Daly, M. (2003). Humans should be individualistic and utility-maximizing, but not necessarily “rational”. Behavioral & Brain Sciences, 26(2), 154-155. [PDF]