Coalitional Psychology 

Us versus them; collective action; perceptions of race; multi-individual cooperation

For information on how coalitional thinking helped shape the outcome of the 2016 US presidential election, see this article with contributions from Leda Cosmides in the New Yorker.


Cooperation between 3 or more individuals who are not kin is rare in the animal kingdom, yet common in our species. How could this have evolved? See:

Tooby, J., Cosmides, L., & Price, M. (2006). Cognitive adaptations for n-person exchange: The evolutionary roots of organizational behavior.Managerial and Decision Economics, 27, 103-129.

Tooby, J. & Cosmides, L. (2010). Groups in mind: Coalitional psychology and the roots of war and morality. In Høgh-Olesen, Henrik (Ed.), Human morality and sociality: Evolutionary and comparative perspectives. (pp.191-234) Palgrave Macmillan.

Pietraszewski, D. (2013). What is group psychology? Adaptations for mapping shared intentional stances. In M. Banaji & S. Gelman (Eds.), Navigating the social world: What infants, children, and other species can teach us (pp. 253-257). New York, NY: Oxford. PDF


Alliance detection:

Is categorizing others by race an (easily reversible) byproduct of a computational system designed to detect who is allied with whom?

“Seeing” others as members of a race may not be inevitable, as many psychologists had thought. Instead, the tendency to notice and remember someone’s race may be a changeable byproduct of brain mechanisms that evolved for another reason: to detect shifting coalitions and alliances. By creating a social context in which race was uncorrelated with coalitional alliances, we were able to drastically decrease the extent to which subjects noticed and remembered other people’s race. Click here for more, also see:

Pietraszewski D, Cosmides L, Tooby J (2014). The content of our cooperation, not the color of our skin: Alliance detection regulates categorization by coalition and race, but not sex. PLoS ONE 9(2): e88534. doi:10.1371/journal.pone.0088534. Click here for UCSB press release.

Kurzban, R., Tooby, J. & Cosmides, L. (2001).  Can race be erased?: Coalitional computation and social categorization.  Proceedings of the National Academy of Sciences, 98(26), 15387-15392. (December 18, 2001; Epub 2001 Dec 11. PMID: 11742078). For The Economist’s article on this work, click here.

Cosmides, L., Tooby, J. & Kurzban, R. (2003). Perceptions of raceTrends in Cognitive Sciences 7(4), 173-179 (April). PMID: 12691766.

Is the mind designed to track accent differences, or is this a byproduct of more general processes? See

Pietraszewski, D. & Schwartz, A. (2014). Evidence that accent is a dimension of social categorization, not a byproduct of perceptual salience, familiarity, or ease-of-processingEvolution and Human Behavior, 35, 43-50. DOI: 10.1016/j.evolhumbehav.2013.09.006 (Supplemental)

What is the relationship between accent, race, and coalitional psychology? See…

Pietraszewski, D. & Schwartz, A. (2014). Evidence that accent is a dedicated dimension of social categorization, not a byproduct of coalitional categorizationEvolution and Human Behavior, 35(1), 51-57. DOI: 10.1016/j.evolhumbehav.2013.09.005


What psychological mechanisms allow people to cooperate in groups? For empirical studies, see…

*Krasnow, M.M., *Delton, A.W., Tooby, J. & Cosmides, L. (2013) Meeting now suggests we will meet again: Implications for debates on the evolution of cooperationNature Scientific Reports, 3, 1747. DOI:10.1038/srep01747
* indicates joint first authorship

Delton, A. W., Cosmides, L., Robertson, T. E., Guemo, M., & Tooby, J. (2012). The psychosemantics of free riding: Dissecting the architecture of a moral conceptJournal of Personality and Social Psychology, 102, 1252-1270. (Supplemental)

Price, M. E., Cosmides, L. & Tooby, J.  (2002). Punitive sentiment as an anti-free rider psychological device.  Evolution and Human Behavior, 23, 203-231. DOI: 10.1016/S1090-5138(01)00093-9

When cooperation is organized as a public good even people who do not contribute can still access the benefits that cooperation creates. How does the structure of public goods affect moral reactions to people who merely opt out of cooperation – even if they do not take the benefits of cooperation? See…

Delton, A. W., Nemirow, J., Robertson, T. E., Cimino, A., & Cosmides, L. (2013). Merely opting out of a public good elicits moralization: An error management approach to cooperationJournal of Personality and Social Psychology. DOI: 10.1037/a0033495 (Supplemental)

Does the human mind contain adaptations for integrating newcomers into coalitions? See…

Cimino, A. & Delton, A. W. (2010). On the perception of newcomers: Toward an evolved psychology of intergeneration coalitionsHuman Nature, 21, 186-202.

Delton, A. W. & Cimino, A. (2010). Exploring the evolved concept of newcomer: Experimental tests of a cognitive modelEvolutionary Psychology, 8, 317-335.

Humans share food and other resources with each other in biologically unprecedented ways. What are some of the psychological abilities that make this possible? See…

Delton, A. W. & Robertson, T. E. (2012). The social cognition of social foraging: Partner selection by underlying valuationEvolution and Human Behavior.

What are relationship representations for? We report new developmental data on one of the core functions of coalitional psychology: using relationship information to make predictions about others. See…

Pietraszewski, D. & German, T.C. (2013) Coalitional psychology on the playground: Reasoning about indirect social consequences in preschoolers and adultsCognition, 126(3), 352-363.