How USA-Centric Is Psychology? An Archival Study of Implicit Assumptions of Generalizability of Findings to Human Nature Based on Origins of Study Samples

Conclusions about human behavior are primarily based upon observations from western, educated, industrialized, rich, and democratic (WEIRD) samples, especially from the United States. One consequence may be the promotion of assumptions that research findings from these populations are more generalizable to humankind than findings from non-WEIRD populations. We tested this with an archival study comparing the extent to which titles of over 5,000 published psychology articles specify samples’ racial/ethnic/national/cultural characteristics—a practice that implies constraints to generalizability. We observed that samples from the United States were less frequently specified in titles compared to both other WEIRD and non-WEIRD regions. Yet, samples from the United States (compared to other regions) were more frequently specified in titles if they referred to racial/ethnic/cultural minorities who may be perceived as exceptions to assumed generalizability of the White American population. These findings suggest that one consequence of a USA-centric sampling bias in psychology may be biased assumptions of (White) people from the United States as especially reflective of humankind.