Thursday, March 19, 2009
Discover Magazine: When we see faces, we don't just recognize them; we also make the same face, if only for a moment. If you see someone wearing a big grin, muscles on your face will start contracting in about a third of a second. The same goes for angry faces and sad ones. We respond this way whether people are looking at us or at someone else.
Mimicking faces is a deep instinct in humans -- babies start doing it days after birth. And our ancestors were probably making these faces for millions of years... We do not mimic faces simply as a side-effect of looking at other people. Experiments show that mimicry actually helps us understand what other people are feeling... When humans mimic others' faces, in other words, we don't just go through the motions. We also go through the emotions.
In some trials subjects chose two words to describe each face's expression, forcing them to consciously reflect on the emotions they saw. In other trials, subjects chose a name for each face, but no attention was drawn to the emotion.
The brain activity in the two groups was strikingly different. When people merely chose a name for an angry face, the amygdala region of the brain became very active. The amygdala plays a central role in how we respond unconsciously to emotional situations. Among the volunteers who used words to describe the faces -- consciously reflecting on the emotions they say -- the amygdalas remained quiet. But an entirely different region, called the right ventrolateral prefrontal cortex, became active. This area is energetic during reflection, reasoning, and self-control.
Image source here.