But there are other possibilities, too. I know that some psychologists rely heavily on psychology students to take their studies. Apart from average age, there might be other things that make psychology students not exactly representative of the general population... such as knowledge of the theories being tested.
One example of such a non-universal fact is the so-called "fundamental attribution error" - people's tendency to blame other people's missteps on their inherent personality defects, but excusing their own by making reference to extenuating circumstances. With a name like that, you might suspect that it was a universal irrational tendency of humankind. Apparently, not so! People in "collectivist" societies allegedly pay more attention to context, and are more likely to say that a person who is angry might be merely having a bad day.
Another example is Maslow's hierarchy of needs, which seem intuitive and obvious to me, but have been criticised as culturally-specific, and also as age-specific.
A third example is the tendency of a large majority of people to rate themselves as above-average in desirable qualities such as intelligence or health, i.e. collective delusion... again, this tendency is much diminished or even perhaps absent in some cultures.
So this raises, like, so many questions. Among them:
- How did it take the field of psychology so long to figure this kind of stuff out? It seems like it should be fairly obvious, if perhaps politically-incorrect these days for someone outside a non-WEIRD culture to point out, that cultures differ in various important ways. Why did no-one think of going to another country and trying to replicate? Expense? Is it really justifiable to be that penny-pinching? Or was there a massive bias against replications in psychology?
- Never mind Western psychologists going to other countries and replicating - aren't there like, actual psychologists in non-WEIRD countries, that could have done this kind of replication a long time ago and published on it? Again, why did this take so long?
- Why does Wikipedia mention not one, not two, but three subfields of psychology that sound like they might cover this sort of thing - cultural psychology, cross-cultural psychology and international psychology? Why so many? What's the difference between them? (It's not super-clear to me from reading their Wikipedia articles.)
- What other "universal" results exist that aren't actually universal? And by all means, let's broaden that question to other social science fields - such as behavioural economics.
- Are any of these cross-cultural differences ones that those of us in WEIRD cultures could learn something from, or benefit by adopting?
Does anyone have any light to shed on any of these questions?