Encyclopedia of Evolutionary Psychological Science

Living Edition
| Editors: Todd K. Shackelford, Viviana A. Weekes-Shackelford

Social Contract Rule Violation

  • Daniel FarrellyEmail author
Living reference work entry
DOI: https://doi.org/10.1007/978-3-319-16999-6_3444-1



When an individual in a social exchange with another “cheats,” by taking a benefit without incurring a cost and/or returning the favor to another.


One of the founding principles of Evolutionary Psychology is that the human mind consists of domain-specific modules that have been shaped by evolution. This modular view of the mind suggests that our ancestors were able to use these modules to help solve specific problems they encountered in their environment. Possibly the most well-known example of such a module is one dedicated to reasoning about social contracts (Cosmides 1989; Cosmides and Tooby 1992). In such contracts, there will be a rule about how an individual is expected to behave (e.g., “if you take a benefit from another individual, then you must return the favor in some form”), and when entering such an exchange each individual is aware of this. According to Cosmides and Tooby (1992), individuals who violate such rules (i.e., “cheats” who take a benefit without incurring a cost or returning the favor) need to be avoided as partners in social contracts, as they will be exploitative and costly with no benefit. Therefore, a “cheater detection” module has evolved in humans which makes us very good at detecting and remembering individuals who cheat in social contracts.

Cosmides and Tooby (1992) provide evidence of this heightened ability to detect cheats in social contracts using the Wason Card Selection Task (Wason 1966). In the standard format of this game, individuals are presented with four cards lying down and are told that each card has a number on one side and a letter on the other. An example of the four cards can be seen in Fig. 1.
Fig. 1

The abstract version of the Wason Selection task

Individuals are then asked which cards they would need to turn over to see if the following rule is correct: “If there is an even number on one side, then there is a vowel on the other.” In this abstract version of the task, few people choose the correct options (the “4” and the “D” card), in fact only about 25% get it right.

However, this changes when the original abstract version of the task is replaced by one that features a social contract (Cosmides and Tooby 1992). For example, in the following version individuals were again presented with four cards but were now told that each card has a drink on one side and a person’s age on the other. An example of this social contract version of the task can be seen in Fig. 2.
Fig. 2

A social contract version of the Wason selection task

Individuals were told to imagine they were working in a bar and had to ensure that the following social contract was upheld: “If a person is drinking alcohol, then they must be twenty-one years old or older.” Compared to the abstract version of the task, a majority of people (approximately 90%) answered correctly (the “Beer” and the “18” card). So why such a difference in accuracy, if the underlying reasoning logic for the two tasks were the same? Cosmides and Tooby (1992) suggest that as the latter version involved a social contract, it activated individuals’ “cheater detection” module, meaning they were better able to spot cheaters here. In other words, drinking alcohol can be considered a social contract, where individuals must incur a cost (i.e., being twenty-one or older) in order to gain a benefit (i.e., drinking alcohol). Therefore, we are better able to identify violations of this rule, which is someone taking the benefit (drinking beer) without incurring the costs (being aged 18), and select those cards accordingly more readily.

Further evidence of the existence of heightened ability to detect social contract rule violation comes when novel or unusual social contracts are used. For example, Cosmides and Tooby (1992) also presented individuals with a similar card task but with a different social contract rule for them to check; “if you get married, you must have a tattoo on your forehead.” Even though this was novel for individuals (compared to the drinking alcohol/age rule), accuracy here was still very high (approximately 75% picked the correct cards). Also, when tested cross culturally, it has been found that performance is similar, which suggests that an ability to detect social rule violators is universal. For example, Sugiyama et al. (2002) found that among the Shiwiar tribe in Ecuador, performance on the social contract versions of the selection (86% selected the correct cards) was very similar to that of the original US sample. This evidence highlights that it is not familiarity with a social contract rule that causes heightened detection of social rule violators but an underlying evolved ability humans have to recognize a social contract whether it is familiar or novel that allows us to detect cheats quickly and accurately.

Evidence also exists that reasoning relating to social contract rule violation is separate to that of similar cognitive abilities. For example, Stone et al. (2002) found that patients with brain damage performed normally on abstract versions of the Wason Selection task, but poorly on versions that involved social contracts. Also, due to the high costs involved in social contracts, the role of emotions in reasoning about social contracts has been shown to be important (Reis et al. 2007) and violations of social contracts elicit anger as the predominant emotion (Fiddick 2004). Finally, recent evidence exploring personality traits as predictors of social contract reasoning has shown that conscientiousness (and to a lesser extent trust) correlates with social contract reasoning abilities (Brase et al. 2019), further showing how human reasoning is affected by social contexts.


By showing that humans would have faced the problem of who to trust in social exchanges, and that we have evolved an ability to understand these social rules, researchers such as Cosmides and Tooby have shown how our cognition can be tuned to certain topics. These topics were relevant in our evolution, and our better reasoning with these than with more abstract topics suggests our minds are built for specific, not general problem-solving.



  1. Brase, G. L., Osborne, E. R., & Brandner, J. L. (2019). General and specific personality traits as predictors of domain-specific and general conditional reasoning. Personality and Individual Differences, 137, 157–164.CrossRefGoogle Scholar
  2. Cosmides, L. (1989). The logic of social exchange: Has natural selection shaped how humans reason? Studies with the Wason selection task. Cognition, 31, 187–276.CrossRefGoogle Scholar
  3. Cosmides, L., & Tooby, J. (1992). Cognitive adaptations for social exchange. In J. Barkow, L. Cosmides, & J. Tooby (Eds.), The adapted mind (pp. 163–228). New York: Oxford University Press.Google Scholar
  4. Fiddick, L. (2004). Domains of deontic reasoning: Resolving the discrepancy between the cognitive and moral reasoning literatures. The Quarterly Journal of Experimental Psychology A, Human Experimental Psychology, 57(3), 447–474.CrossRefGoogle Scholar
  5. Reis, D. L., Brackett, M. A., Shamosh, N. A., Kiehl, K. A., Salovey, P., & Gray, J. R. (2007). Emotional intelligence predicts individual differences in social exchange reasoning. NeuroImage, 35(3), 1385–1391.CrossRefGoogle Scholar
  6. Stone, V. E., Cosmides, L., Tooby, J., Kroll, N., & Knight, R. T. (2002). Selective impairment of reasoning about social exchange in a patient with bilateral limbic system damage. Proceedings of the National Academy of Sciences of the United States of America, 99(17), 11531–11536.CrossRefGoogle Scholar
  7. Sugiyama, L., Tooby, J., & Cosmides, L. (2002). Cross-cultural evidence of cognitive adaptations for social exchange among the Shiwiar of Ecuadorian Amazonia. Proceedings of the National Academy of Sciences, 99, 11537–11542.CrossRefGoogle Scholar
  8. Wason, P. (1966). Reasoning. In B. M. Foss (Ed.), New horizons in psychology. Harmondsworth: Penguin.Google Scholar

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© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.University of WorcesterWorcesterUK

Section editors and affiliations

  • Kevin Kniffin
    • 1
  1. 1.Cornell UniversityIthacaUSA