New research from the Czech Republic finds people can accurately judge intelligence by looking at faces of men, but not women.

Can you tell whether someone is smart just be looking at them? It sounds preposterous, but new research from the Czech Republic suggests you can—if the subject in question is a man.

The results of a just-published study “suggest that a perceiver can accurately gauge the real intelligence of men, but not women, by viewing their faces in photographs,” writes a research team led by Karel Kleisner of Charles University in Prague.

The study, in the journal PLoS One, reports people tend to associate certain facial traits with high intelligence. The researchers report these notions “represent nothing but a cultural stereotype,” but some still-unidentified visual cues apparently point them in the right direction.

"The strong halo effect of attractiveness may thus prevent an accurate assessment of the intelligence of women."

The study featured 160 participants who looked at photographs of 80 Czech university students (40 men and 40 women). The images were close-ups of the students’ faces, which featured a neutral, non-smiling expression, and were devoid of jewelry and cosmetics.

Each of the pictured students completed a Czech version of the Intelligence Structure Test, which utilizes a variety of tools to measure different types of intelligence (including IQ).

Using as much time as needed, each participant rated all 80 faces for either intelligence or attractiveness, using a one-to-seven (highest to lowest) scale. The researchers then averaged the intelligence and attractiveness scores each student received.

“Our raters (men and women alike) were able to estimate intelligence with an accuracy higher than chance from static facial photographs of men, but not from photos of women,” the researchers report.

Specifically, they write, “two factors of general intelligence were significantly associated with perceived intelligence from men’s faces: fluid intelligence and figural intelligence. Fluid intelligence is the capacity to logically solve problems independent of acquired knowledge. Figurative intelligence describes the ability to handle objects such as images, patterns and shapes.”

Clearly, the research (if successfully replicated) leaves us with two big questions: What presumably unconscious mental process allows people to spot intelligence? And whatever this technique turns out to be, why doesn’t it work when we’re judging women?

The researchers rule out “shape variability” as the signal, but don’t have a good alternative answer. “We can speculate about attributions of intelligence based on particular configurations of eyes or gaze, color of eyes, hair and skin, or skin texture,” they write.

On the inability to accurately judge women’s intelligence, the researchers point to several possibilities. Perhaps, they write, cues of higher intelligence are apparent only in men’s faces “due to some genetic and developmental association to sex-steroid hormonal agents during puberty.”

“Another option is that women are pervasively judged according to their attractiveness,” they add. “The strong halo effect of attractiveness may thus prevent an accurate assessment of the intelligence of women.”

Determining the truth will require a lot of hard work by very intelligent people. Have you seen any?