We all know that you shouldn’t judge a book by its cover. But we all do it anyway. If I were to show you some faces, you’d find it pretty easy to make a snap judgment of –say – how clever they look. But this would just be prejudice, right? You couldn’t, just by looking, guess people’s actual intelligence. Could you?

Let’s try. Below are three men. Rank them in order of intelligence from most to least (these aren’t real people, but composites created – in each case – by averaging across lots of difference faces).

Image And now the same for women.Image

Scroll down to find out the rankings that most people give.


For the male faces, most people rate the man on the right as the most intelligent, and the man on the left as the least. For the female faces, most people rate the woman on the left as the most intelligent, and the woman on the right as the least (in both cases, the middle faces are in between).

But these are just stereotypes, right? No. When researchers in the Czech Republic asked people to estimate the intelligence of 80 biology students on the basis of facial photographs, a significant correlation was observed between perceived and actual intelligence (as measured by an IQ test); but only for men.

Admittedly, the relationship was small. Statisticians express the relationship between two measures using a number called a correlation coefficient (sometimes abbreviated to r). This number ranges between 0 (i.e., no relationship between face-ratings and IQ-test scores) and 1 (i.e., you can perfectly predict anyone’s IQ on the basis of the face-rating). On this scale, the correlation between perceived and actual intelligence for men was tiny[i]r=0.06 – though easily statistically significant. The concept of statistical significance is explained in detail in the book version of Psy-Q (look for the section The Tea Test), but the take-home message is this: The likelihood of researchers finding an apparent relationship between perceived and actual intelligence of this size (i.e., r=0.06 on the 0-1 scale) by chance alone, if none actually existed, is less than 1 in 1,000.

Two unsolved puzzles remain. First, why is it that we can read intelligence in the faces of men (at least to a modest degree), but not women? Perhaps, in evolutionary terms, giving off signals of intelligence is more important for men than women. Indeed, cross cultural studies tell us that – pretty much universally – women value intelligence much more than do men when seeking a partner (You can take this “Perfect Partner” test yourself in the book version of Psy-Q, as well as measuring your own IQ, and completing other face-rating tasks looking at trustworthiness, aggression and attractiveness).

Another possibility is that, when asked to rate intelligence in women’s faces, the raters (both men and women) couldn’t help being swayed by attractiveness (what researchers call a “halo effect”). Indeed, the relationship between rated attractiveness and rated intelligence for female faces was r=0.9 on the 0-1 scale, meaning that the two are almost interchangeable (the corresponding figure for male faces was r=0.5).

The second remaining question is just what features of men’s faces raters were using to predict intelligence (which, remember, they were able to do at way above chance levels). The researchers found that, on the whole, faces that were rated as intelligent tended to be long and thin with larger noses, while those that were rated as less intelligent tended to be rounder and fatter with small noses. But, confusingly, when they fed these measurements into the computer, they did not predict IQ-test scores, just perceived intelligence.

So, for now, this second puzzle remains unsolved: We don’t know exactly what features people use to correctly predict intelligence in male faces. The researchers speculate that it may be “particular configurations of eyes or gaze, colour of eyes, hair and skin, or skin texture”. What we need now is studies that tease apart these possibilities (for any psychology students reading this, this might be an interesting idea for a 3rd year project, if you can find a suitable supervisor).

In the meantime, the findings of this study suggest that people not only do judge a book by its cover but – to at least some extent – are justified in doing so. So, whilst we don’t yet know exactly what this entails, then the lesson – particularly if you are a man – is clear: Look sharp!

This is a sample chapter in the style of Psy-Q by Ben Ambridge, forthcoming from Profile Books (UK) and Penguin (US).  For details click here

Kleisner, K., Chvátalová, V., & Flegr, J. (2014). Perceived Intelligence Is Associated with Measured Intelligence in Men but Not Women. PloS one9(3), e81237.

Buss, D. M. (1989). Sex differences in human mate preferences: Evolutionary hypotheses tested in 37 cultures. Behavioral and Brain Sciences, 12, 1–14.


[i] One reason that the effect is tiny is that the researchers had to control for ratings of attractiveness, which is highly correlated with perceived intelligence (r=0.5 for men).

112 thoughts on “Look Sharp!

  1. People have too many clichés sitting in their head:) Also, your rating depends on your own intelligence and character in the first place. Great reading, thanks!

  2. Remember though we are still evolutionary driven biological machines. Nature has crafted our individual bodies to adapt to our environments and to inherit traits of our predecessors.

    A study I read once mentioned broader jaws and a predisposition to fight, because a broader jaw meant a sturdier jaw. Likewise a bigger nose meant more oxygen to the brain and more sensory input to make decisions with quicker in a shorter time. Just those two things alone make the male on the left appear lesser than the person on the right…but the leftie looks like he could beat up the righty.

  3. Much to be said about keeping an open mind when you meet people, but I am certain everyone has preconceived ideas when they meet someone… Until that someone proves them wrong. I have always thought about this subject, especially when you hear comments like… ‘He doesn’t look like a killer’. What exactly is a killer supposed to look like, or a smart or dumb person for that matter?!?! It’s great to read research about this.

  4. This was truly educational for someone like myself. All I can contribute is that my husband is a genius by IQ standards and he does have a longer more narrow face, BUT his nose is also narrow (hmm). And as for myself, I’ve never taken an IQ test. I think I’m too scared to attempt it, wouldn’t want to know the results. I like to think of myself as street savvy. I’ll let my husband fill me in on space-time continuum theories and learn the rest from Neil Degrasse Tyson on his Cosmos segments.

  5. I went by which faces looked more open and yes, I did choose the male on the right and the female on the left as most ‘open’ and therefore intelligent. Interesting read.

  6. Very Good Post, it kinda make me sick if a person whose well dress and smell nice tries out for a job, then a person with a tatoo perhaps mohawk dress nice try to get a job, whose gonna the job? I never look at people and judge them i have 3 points to base my judgement off of. personality, behaviour, and body language. i never get caught up in people apperance or looks. GREAT POST. http://www.averykey.wordpress.com come by sometime

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  8. Does this have anything to do with our evolution? Going to back to who looks the most ‘Neanderthal-like’ and who looked the most ‘evolved’? I don’t know how that helps with women though. Interesting.

  9. Very interesting! I never knew that you could actually tell a person’s intelligence in this way! I do believe studies have shown that “women” are the truer in intelligence (not to toot any horns here…lol) but after this article I have to say i’m thinking we are both on the same level… although, both genders are prone to making the same idiotic mistakes in life:) Anyway-thanks for sharing a great uniquely written concept in an article for all of us to read!

  10. If you look closely you will see that the 3rd man and the 1st woman have perfectly proportioned faces. The distance between the top of the forehead to the eyebrows is the same as the distance between the eyebrows to the tip of the nose, and the tip of the nose to the bottom of the chin. Humans equate attractiveness with proportionality. Perhaps the same is true for intelligence.

  11. I don’t know if I tried to judge intelligence by face but by the attitude and how they talk but I will give it a try.
    For men : 1, 2, 3 and for Women : 1,3,2 :) I didn’t look to see what other people answered before me because I want to play fair. ;))

  12. As someone who is very interested in evolutionary psychology, this is a great read. There’s still much that can be studied in this field.

    -Niq (20somethingmedlife)

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