In the 19th century some scientists said the inferiority of women’s intellect could be attributed to their lighter and smaller brains. And today, with more sophisticated tools like brain imaging, scientists often link brain structure and function to psychological behavior.

We should take such findings with extreme caution. So says a review published this week in Current Directions in Psychological Science.

Most neuroimaging studies are conducted with small numbers, like 20 subjects, where differences could easily be due to chance. Additionally we currently have little understanding for how neural structures influence complicated behaviors.

For instance, a 2005 20-person study using fMRI found that for women the left-prefrontal cortex was more active than in men when they were shown the same funny cartoons. This led to all kinds of interpretations by the media including a famous Vanity Fair article by Christopher Hitchens stating that women had to work harder to get jokes, if they got them at all.

Neuroscientists conducting the research know that any small difference in such a small sampling does not lead to an overall generalization. But the popular press often grabs hold of these conclusions because they are easy, and make for an interesting story. So reader beware: If it seems too amazing to be true, it probably is.

—Christie Nicholson