The brain's "concern mechanism" is activated when people watch someone with a sad facial expression tell an unhappy story, according to a study published in the journal Neuropsychologia (Vol. 41, No. 2). But an entirely different set of brain areas is activated when the content of the story and the facial expression of the storyteller don't match.
The study offers a new look at how we perceive and react to others' emotions. It also provides support for a "shared representations" model of sympathy, in which sympathizing with someone else activates the same brain regions that would be activated if one were experiencing the emotion.
Neuroscientist Jean Decety, PhD, and graduate student Thierry Chaminade of the University of Washington's Center for Mind, Brain and Learning videotaped actors telling sad or neutral stories while making sad, neutral or happy facial expressions. They then showed the videotapes to 12 male volunteers and measured their brain activity using positron-emission tomography.
They found that the brain activity of participants who listened to sad stories increased in regions associated with emotion, such as the amygdala, but only when the actors' expressions were consistent with the stories they told. The premotor cortex and other brain regions associated with motor representations also became more active.
When the actors' facial expressions didn't match their stories, however, a different set of brain areas was activated. Those areas included the ventromedial prefrontal cortex, which plays a role in understanding social stimuli.
Participants also showed a distinct physiological response to the mismatch, with higher skin conductance than in the other conditions. And while they felt sympathetic toward people who told sad stories with a sad expression, they actively disliked those who told sad stories with a smile.
"The activations are caused, or triggered, by the experience of listening to someone else's sad experience," says Decety. When that experience isn't convincing--as when facial expressions and stories don't match--brain activity shifts from areas associated with emotions and shared motor representations to areas associated with resolving conflicting signals.