In romantic relationships, men are much more likely than women to overestimate the likelihood of their partner’s infidelity. According to an article published in the journal Evolutionary Psychology, this overestimation may be a cognitive bias with an important evolutionary function.
Two studies, conducted by Aaron T. Goetz and Kayla Causey, recruited a total of 312 college students to investigate the difference in perceptions of infidelity in men and women. All participants in the study were involved in heterosexual relationships.
Both studies found that men were more suspicious of future infidelity in their relationship than women, although men also reported being more likely to be unfaithful to their partner in the future.
The authors of this study believe the difference in perceptions of infidelity can be attributed to a cognitive bias in men.
“Cognitive biases refer to particular patterns in perception, judgment, or decision making in which an error is predictably made. Cognitive biases have been understood as evolved information-processing mechanisms that are biased to err in a specific direction regardless of objective reality.”
In this case, the cognitive bias in men is to err in the direction of suspecting infidelity. Although both men and women have an stake in detecting infidelity, from an evolutionary perspective, the consequences of not detecting infidelity can be more serious for men than for women.
“Ancestral men, however, were susceptible to an additional and profound cost if they failed to detect a partner’s infidelity: cuckoldry – the unwitting investment of resources into genetically unrelated offspring.”
Whereas a woman can be very certain, for obvious reasons, that a child is her’s, a man does not have this certainty and may invest time and resources into a child that is not genetically related to himself.
Thus, the evolutionary cost of infidelity may be more serious for men than for women. If this is the case, then the oversensitivity to perceptions of infidelity could be an evolutionary mechanism designed to enhance men’s genetic fitness.
Goetz, A.T. & Causey, K. (2009). Sex differences in perceptions of infidelity: Men often assume the worst. Evolutionary Psychology, Vol 7, No 2: 253-263. Full text: http://www.epjournal.net/filestore/ep07253263.pdf