Psychology is biased. At least. Perhaps it is wrong at all

Is psychology a form of Western dominance?
Does it have anything relevant to tell us about humanity in general or merely few words about a small non-representative segment of Western society?

Yet psychologists base most of their generalizations about human nature on studies of our own narrow and atypical slice of human diversity. Among the human subjects studied in a sample of papers from the top psychology journals surveyed in the year 2008, 96% were from Westernized industrial countries (North America, Europe, Australia, New Zealand, and Israel), 68% were from the U.S. in particular, and up to 80% were college undergraduates enrolled in psychology courses, i.e., not even typical of their own national societies. That is, as social scientists Joseph Henrich, Steven Heine, and Ara Norenzayan express it, most of our understanding of human psychology is based on subjects who may be described by the acronym WEIRD: from Western, educated, industrialized, rich, and democratic societies. Most subjects also appear to be literally weird by the standards of world cultural variation, because they prove to be outliers in many studies of cultural phenomena that have sampled world variation more broadly. Those sampled phenomena include visual perception, fairness, cooperation, punishment, biological reasoning, spatial orientation, analytic versus holistic reasoning, moral reasoning, motivation to conform, making choices, and concept of self. Hence if we wish to generalize about human nature, we need to broaden greatly our study sample from the usual WEIRD subjects (mainly American psychology undergraduates) to the whole range of traditional societies.

Excerpt from Jared Diamond, “The world until yesterday: What Can We Learn from Traditional Societies?“, Viking: 2012