Evolutionary Psychology Has Problems; and It Isn’t Getting Better

Evolutionary psychology (EP) attempts to study how evolution has shaped our brains, thoughts and behaviour. However, it's ability to obtain reliable results is hampered by the fact it's trying to study all humans yet 75% of EP research is conducted only on Westerners. Of course, I'm hardly breaking new ground with this criticism; researchers have been pointing it out for years. Which raises the question: is all this criticism having an impact? Is evolutionary psychology improving?

The criticism

The issue of sampling practices in psychology is an old one. If your research doesn't examine a representative cross-section of the population then your results may not apply to the whole population. In fact, they might not apply to anyone outside the narrow group you examined; effectively meaning you wasted your time. As a result of this late last century people were debating over whether psychology examined enough non-whites ¹, or whether it focused too much on university students ².

In recent years the focus has shifted somewhat. People began asking "even if we studied a perfect cross-section of America would those results be representative of humanity as a whole?" The answer seemed to be no ³. In 2008, Arnett hammered this problem home publishing one of the largest reviews of psychology research ever. He found that 95% of research examined WEIRD populations ⁴. That's 95% of research conducted on an unrepresentative sample.

Most of this discussion may have focused on psychology in general, but EP has been paying attention. Researchers have written about how Arnett's results do not bode well for the field ^3,5 and the eponymous textbook Evolutionary Psychology devotes a fair bit of time to how bad sampling practices are bad ⁶. And that's not counting all the blogs, books and other articles on the issue.

In short, evolutionary psychology knows using WEIRD samples too much is bad. So surely their use is decreasing over time, in favour of more representative samples that would produce more reliable results?

The test

Last week I wrote about a review of EP research I conducted. At the end of that little experiment I was left with a lot of data on how much EP research used WEIRD samples from 2003 - 2007 and in 2013. So having finished with my previous review, I went over to this data set and asked it "has the use of such samples been decreasing over time?"

Hopefully you all read the headline of this post before clicking on it so by now you know the answer: No.

As you can see - aside from a brief dip in 2005 - there was effectively no change over this period. Statistics confirms this; indicating there was not a statistically significant change in the use of WEIRD samples from 2003 - 2007. As if that wasn't bad enough, when you break it down by journal it turns out that some have actually increased their use of WEIRD samples.

" But Adam" I hear my dear readers ask, " these results are from 2007. Surely it's unfair to dismiss evolutionary psychology based on old data ". And right you are, reader who lives in my head. Which is why I also examined the latest complete issue of these journals (which was at the time the 2013 issue).

And the results, sadly, were the same. There was no statistically significant decrease in the use of WEIRD samples between the 2003 - 2007 data and the 2013 data. Evolutionary psychology has had 10 years to get its act together, and it has completely failed. Which is a real shame because this is a field with so much potential. It could tell us so much. Yet at the moment it's often being done badly; and it doesn't show any signs of changing.

References

1. Graham, S. (1992). " Most of the subjects were White and middle class": Trends in published research on African Americans in selected APA journals, 1970-1989. American Psychologist, 47(5), p.629.

2. Sears, D. (1986). College sophomores in the laboratory: Influences of a narrow data base on social psychology's view of human nature.Journal of personality and social psychology, 51(3), p.515.
3. Henrich, J., Heine, S. and Norenzayan, A. (2010). Beyond WEIRD: Towards a broad-based behavioral science.Behavioral and Brain Sciences, 33(2-3), pp.111-135.
4. Arnett, J. (2008). The neglected 95%: why American psychology needs to become less American.American Psychologist, 63(7), p.602.
5. Henrich, J., Heine, S. and Norenzayan, A. (2010). The weirdest people in the world?.Behavioral and brain sciences, 33(2-3), pp.61-83.

6. Buss, D. (2008). Evolutionary psychology. 3rd ed. Boston: Allyn and Bacon.