Face to Face with the Emotional Brain
Amygdala responses to the facial signals of others predict both normal and abnormal emotional states. An understanding of the brain chemistry underlying these responses will lead to new strategies for treating and predicting psychopathology.
One of our favorite scientific studies of the past few years is a laboratory assessment of how people react to strangers, conducted by Alex Todorov and colleagues at Princeton.1 They presented subjects with pictures of faces—many faces—that they had never seen before. All of the faces were intended to have no discernable expression, that is, they wore neutral expressions. The subjects were asked to rate how trustworthy they thought each face was based on a gut reaction. Naturally, each subject thought that some of the faces were more trustworthy-looking, some were less trustworthy-looking, and some were neutral. At the same time, the response of each subject’s amygdala—a deep brain structure—was measured using functional magnetic resonance imaging (fMRI).
The measured responses showed some relationship with the judgments the subjects made about the faces. Specifically, the amygdala responses were greatest to faces judged to be the most untrustworthy. As cool as that is, it was not the most interesting finding.