Western, Educated, Industrialized, Rich, and Democratic, that is. One of the common complaints about evolutionary psychology is that it claims to be addressing evolved human universals, but when you look at the data sets, they are almost always drawn from the same tiny pool of outliers, Western undergraduate students enrolled in psychology programs, and excessively extrapolated to be representative of Homo sapiens — when we’re actually a very peculiar group.

How peculiar? A paper by Henrich, Heine, and Norenzayan, “The Weirdest People in the World”, tries to measure that…and by nearly every standard they looked at, the wealthy inhabitants of democratic western societies are not exactly normal (that is, they’re far from average in ways both good and bad and value neutral).

Who are the people studied in behavioral science research? A recent analysis of the top journals in six sub‐disciplines of Psychology from 2003‐2007 revealed that 68% of subjects came from the US, and a full 96% of subjects were from Western industrialized countries, specifically North America, Europe, Australia, and Israel (Arnett 2008). The make‐up of these samples appears to largely reflect the country of residence of the authors, as 73% of first authors were at American universities, and 99% were at universities in Western countries. This means that 96% of psychological samples come from countries with only 12% of the world’s population. Put another way, a randomly selected American is 300 times more likely to be a research participant in a study in one of these journals than is a randomly selected person from outside of the West.

It’s even worse: “67% of the American samples (and 80% of the samples from other countries) were composed solely of undergraduates in psychology courses”.

That wouldn’t be so bad if we were examining traits that were truly universal, or if we had a better understanding of exactly what properties were unusual and derived. Fruit flies are also real oddball organisms, but we can still learn a lot from taking them apart…as long as we don’t simply pretend that people and mice and beetles and clams are all just like flies. Lab rats have their place, but understanding the bigger picture needs more diversity.

So it is possible that maybe the results aren’t significantly biased by sampling error if there weren’t much variation anyway. Unfortunately for the psychological universalists, that doesn’t seem to be the case. The paper describes many differences between cultures, some of which one might be willing to argue are fairly superficial: some societies have homosexual activities as an important step in the rituals of becoming a man, for instance, and while many of us might find that uncomfortable, we can see a range of sexual preferences even within the WEIRD group. But others violate properties I’ve always taken for granted.

For instance, in neuroscience and psychology you’ll see this optical illusion all the time, the Mueller-Lyer illusion. The two lines are exactly the same length, but we perceive them as longer or shorter depending on the direction of the arrows.

Wait, “we”? Yeah, I do, most of you readers probably do too, and every time I’ve seen this illusion in the text books it’s presented as a fait accompli — but of course you will see this dramatic illustration of how the brain processes visual stimuli!

Only, they don’t. The magnitude of the effect is culture-dependent. In a series of tests in which the lines were adjusted until the viewer saw them as equal in length, different groups saw different things. The WEIRD group needed one line extended a great deal before they saw them as equal; the African San scarcely saw the illusion at all.

Mueller‐Lyer Results for Segall et. al.’s cross‐cultural project. PSE is the percentage that segment ‘a’ must be longer than ‘b’ before individuals perceive them as equal.

The paper goes through multiple examples of this kind of variable phenomena: economic decision making (not everyone thinks like a trader), biological reasoning (Western people are marked by a deep ignorance of other organisms), spatial cognition (how do you see yourself and others relative to landmarks?), and the individual’s relationship to society. They also identify properties that do seem to be common across populations…and that’s the nub of the argument here.

No one is denying that there are almost certainly deep commonalities between all members of our species. But there are also phenomena that are much more fluid, and sometimes those phenomena are so deeply ingrained in contemporary culture that we assume that they must be human universals — we assume our personal differences and biases must be shared by all right-thinking, decent human beings. But you can’t know that until you look, and your personal prejudices do not count as data.

It takes hard work to identify the real common threads of our humanity, and it can be rewarding to see which bits of our identity are actually superficial, not an essential part of our generally human self. The authors advocate more care in interpretation and wider empirical research.

Many radical versions of cultural relativity deny any shared commonalities in human psychologies across populations. To the contrary, we expect humans from all societies to share, and probably share substantially, basic aspects of cognition, motivation, and behavior. As researchers who see much value in applying evolutionary thinking to psychology and behavior, we have little doubt that if a full accounting were taken across all domains among peoples past and present, that the number of similarities would indeed be large, as much ethnographic work suggests (e.g., Brown 1991)—ultimately, of course, this is an empirical question. Thus, our thesis is not that humans share few basic psychological properties or processes; rather we question our current ability to distinguish these reliably developing aspects of human psychology from more developmentally, culturally, or environmentally contingent aspects of our psychology given the disproportionate reliance on WEIRD subjects. Our aim here, then, is to inspire efforts to place knowledge of such universal features of psychology on a firmer footing by empirically addressing, rather than dismissing or ignoring, questions of population variability.

Perspective is needed. The ridiculous bias in most psychology studies might be unavoidable — not every undergraduate psychology can afford to fly to deepest Uganda or the Chinese hinterlands to broaden the cultural background of their research — but we could at least have greater caution in claiming breadth. I thought this suggestion was amusing:

Arnett (2008) notes that psychologists would surely bristle if journals were renamed to more accurately reflect the nature of their samples (e.g., Journal of Personality and Social Psychology of American Undergraduate Psychology Students). They would bristle, presumably, because they believe that their findings would broadly generalize. Of course, there are important exceptions to this general tendency as some researchers have assembled a broad database to provide evidence for universality (e.g., Buss 1989, Daly & Wilson 1988, Tracy & Matsumoto 2008).

I don’t think the specificity of that journal title would diminish its interest, and it would be a heck of a lot more accurate. We already have specialty science journals for Drosophila, zebrafish, nematodes, etc., so why not give the American Undergraduate Psychology Students the recognition they deserve as a standard model organism?

(via The Pacific Standard)