Most of us reflexively grin when we see another beaming face and grimace when we see a comrade in pain. New research suggests that such mimicry helps people—especially women—more quickly grasp others’ emotional expressions.

In their recent study Dutch psychologists Marille Stel of Leiden University and Ad van Knippenberg of Radboud University Nijmegen showed 62 research participants a series of photographs of faces, each for less than a tenth of a second. After viewing each face, participants pressed a button to indicate whether the image displayed positive or negative emotion. For half the experimental trials, Stel and van Knippenberg instructed participants to avoid mimicking the faces’ emotional expressions and to clench their teeth, which hindered their ability to do so. In a control condition, participants were asked to hold their shoulders still as they responded, a constraint that the researchers believed was about as distracting as having to avoid moving facial muscles. The investigators measured how quickly participants responded to each face and found that when women were free to mimic emotional expressions, they were faster than men were to recognize whether the emotion was positive or negative. When mimicry was constrained, the men were not affected, but the women slowed down to the males’ speed.

The results square with brain-imaging studies that suggest that our brain possesses a shortcut for processing emotional expressions, the authors say. The findings also hint that women may make more use of this biological shortcut than men do. Social psychologist Dacher Keltner, who studies emotions at the University of California, Berkeley, says the study is important because it corroborates other work showing that, as compared with men, women report greater correspondence between their own emotions and those of others and that they experience higher levels of empathy. Most existing data, Keltner explains, depend on research participants’ self-reported perceptions: “This study shows that these gender differences are also observed in very fast, behavioral mimicry.”

What remains unknown is how commonly people mimic emotional expressions in natural circumstances or whether mimicry is essential for the “fast route” that women take to emotion recognition, according to psychologist Simon Baron-Cohen of the University of Cambridge. “Certainly there is lots of evidence that females have a stronger drive to empathize, but whether this is mimicry-mediated remains to be firmly established. This new study is at least consistent with that possibility,” he says.

Note: This article was originally printed with the title, "More Than Flattery".