While physical is an integral part of mate selection, the evidence suggests that concerns for mate selection are not the reason people think that beautiful people are more intelligent. First, children as young as kindergarteners share the perception that beautiful people are more competent. Asked to choose between two teachers, one more physically attractive than the other, many kindergarteners prefer the more attractive teacher because they believe she is more competent and nicer. Second, more importantly, among adults, the common perception holds both within and between the sexes. Not only do men believe that more attractive women are more intelligent and women believe more attractive men are more intelligent, but men also believe that more attractive men are more intelligent and women also believe that more attractive women are more intelligent. Since 5-year-olds are typically not concerned with mate selection, and since most people are heterosexual, these two pieces of evidence suggest that there is more going on than concerns of mate selection.

Sociologists and social psychologists, convinced (and politically predisposed to believe) that “beauty is in the eye of the beholder” and “beauty is only skin-deep,” dismiss this widespread perception as “ ,” stereotype,” or “halo effect,” with the implicit assumption that the perception is not accurate and has no factual basis. It is a stereotype that beautiful people are more intelligent. But, as I explain in an earlier post, virtually all stereotypes are empirically true; if they were not true, they would not be stereotypes in the first place. And it turns out that this one is no exception. People believe beautiful people are more intelligent, because they in fact are.

The National Longitudinal Study of Adolescent Health (Add Health), conducted by a team of researchers at the University of North Carolina – Chapel Hill, is one of the very few social science datasets that take biological and genetic influences on human behavior seriously. As a result, Add Health routinely measures both the intelligence and physical attractiveness of its respondents.

In the Wave III of Add Health, conducted in 2000-2001, respondents take an IQ test called the Peabody Picture Vocabulary Test. And then their physical attractiveness is measured objectively by an interviewer, who is unaware of their IQ test scores, on a 5-point scale (1 = Very unattractive, 2 = Unattractive, 3 = About average, 4 = Attractive, and 5 = Very attractive). The following graph shows the association between Add Health respondents’ physical attractiveness and their intelligence. The data come from a large (n = 15,197) nationally representative sample of young Americans (mean age = 22).

As you can see, there is a clear monotonic positive association between physical attractiveness and intelligence. The more physically attractive Add Health respondents are, the more intelligent they are. The mean IQ is 94.2 for those rated “very unattractive,” 94.9 for those rated “unattractive,” 97.1 for those rated “about average,” 100.3 for those rated “attractive,” and 100.7 for those rated “very attractive.” Due partly to the large sample size, the association is highly statistically significant.

As I explain in earlier posts, both intelligence and physical attractiveness are correlated with ; men on average are slightly more intelligent than women, and women on average are physically more attractive than men. So it is important to see what the association between physical attractiveness and intelligence looks like within each sex. The following two graphs reproduce the association separately for each sex.

The graphs show that the association is no longer monotonic among either women or men, but the general positive association still holds for both sexes. “Very attractive” women are on average more intelligent than “very unattractive” women by about 6 IQ points. Similarly, “very attractive” men are on average more intelligent than “very unattractive” men by about 8 IQ points.

So it appears that the “stereotype” that beautiful people are more intelligent appears to be true empirically, just as virtually all “stereotypes” are. But now the question is: Why? Why are beautiful people more intelligent? I will address this question in my next post.