Behavioral scientists routinely publish broad claims about human psychology and behavior in the world's top journals based on samples drawn entirely from Western, Educated, Industrialized, Rich, and Democratic (WEIRD) societies. Researchers – often implicitly – assume that either there is little variation across human populations, or that these “standard subjects” are as representative of the species as any other population. Are these assumptions justified? Here, our review of the comparative database from across the behavioral sciences suggests both that there is (...) substantial variability in experimental results across populations and that WEIRD subjects are particularly unusual compared with the rest of the species – frequent outliers. The domains reviewed include visual perception, fairness, cooperation, spatial reasoning, categorization and inferential induction, moral reasoning, reasoning styles, self-concepts and related motivations, and the heritability of IQ. The findings suggest that members of WEIRD societies, including young children, are among the least representative populations one could find for generalizing about humans. Many of these findings involve domains that are associated with fundamental aspects of psychology, motivation, and behavior – hence, there are no obviousa priorigrounds for claiming that a particular behavioral phenomenon is universal based on sampling from a single subpopulation. Overall, these empirical patterns suggests that we need to be less cavalier in addressing questions ofhumannature on the basis of data drawn from this particularly thin, and rather unusual, slice of humanity. We close by proposing ways to structurally re-organize the behavioral sciences to best tackle these challenges. (shrink)

Our discussion of the commentaries begins, at the evolutionary level, with issues raised by our account of the evolution of morality in terms of partner-choice mutualism. We then turn to the cognitive level and the characterization and workings of fairness. In a final section, we discuss the degree to which our fairness-based approach to morality extends to norms that are commonly considered moral even though they are distinct from fairness.

Can the perception that one’s partner is investing effort generate a sense of commitment to a joint action? To test this, we developed a 2-player version of the classic snake game which became increasingly boring over the course of each round. This enabled us to operationalize commitment in terms of how long participants persisted before pressing a ‘finish’ button to conclude each round. Our results from three experiments reveal that participants persisted longer when they perceived what they believed to be (...) cues of their partner’s effortful contribution. Crucially, this effect was not observed when they knew their partner to be an algorithm, nor when it was their own effort that had been invested. These results support the hypothesis that the perception of a partner’s effort elicits a sense of commitment, leading to increased persistence in the face of a temptation to disengage. (shrink)

Can the perception that one’s partner is investing effort generate a sense of commitment to a joint action? To test this, we developed a 2-player version of the classic snake game which became increasingly boring over the course of each round. This enabled us to operationalize commitment in terms of how long participants persisted before pressing a ‘finish’ button to conclude each round. Our results from three experiments reveal that participants persisted longer when they perceived what they believed to be (...) cues of their partner’s effortful contribution. Crucially, this effect was not observed when they knew their partner to be an algorithm, nor when it was their own effort that had been invested. These results support the hypothesis that the perception of a partner’s effort elicits a sense of commitment, leading to increased persistence in the face of a temptation to disengage. (shrink)