How diverse were the samples in two evolutionary psychology journals?

Details

Psychologists often infer characteristics of populations from small samples, raising questions about how well those samples generalize. There is a consensus that psychology probably relies too heavily on samples from Western, Educated, Industrialised, Rich and Democratic (WEIRD) societies and on university students. Online surveys might increase diversity, but online sampling also reaches only a restricted range of participants.

Evolutionary psychology studies often seek evolved universal characteristics, potentially making diverse samples especially relevant. The researchers empirically examined samples used in the 2015–2016 volumes of Evolution & Human Behavior (104 articles) and Evolutionary Psychology (76 articles). Their database contained 311 human samples, with a median sample size of 186.

Online or student samples accounted for 70% of samples, followed by other Western adult samples at 19%. In total, 253 samples (81%) were classified as Western, meaning Europe, North America or Australia. The remaining samples were predominantly from Asia (N = 37; 12%), mostly Japan. Only a small fraction came from Latin American and Caribbean countries (N = 8) or African countries (N = 6).

Median sample size did not differ significantly between continents, but online samples, both paid and unpaid, were typically larger than those sourced offline. The samples appeared more diverse than those reported in reviews of social and developmental psychology literature. The authors suggested this might reflect evolutionary psychology’s greater inherent need to test hypotheses about evolved, universal human nature. Nevertheless, most samples in contemporary evolutionary psychology research remained WEIRD.