Inferring Other People's Actions and Intentions

Giacomo Rizzolatti, Leonardo Fogassi, and Vittorio Gallese, "Mirrors in the Mind," Scientific American 54 (November 2006):

John watches Mary, who is grasping a flower. John knows what Mary is doing--she is picking up the flower--and he also knows why she is doing it. Mary is smiling at John, and he guesses that she will give him the flower as a present. The simple scene lasts just moments, and John's grasp of what is happening is nearly instantaneous. But how exactly does he understand Mary's action, as well as her intention, so effortlessly?

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[Our research group] found that answer somewhat accidentally in a surprising class of neurons [which we later called "mirror neurons"] in the monkey brain that fire when an individual performs simple goal-directed motor actions...

... John grasps Mary's action because even as it is happening before his eyes, it is also happening, in effect, inside his head. It is interesting to note that philosophers in the phenomenological tradition long ago posited that one had to experience something within oneself to truly comprehend it. But for neuroscientists, this finding of a physical basis for that idea in the mirror neuron system represents a dramatic change in the way we understand the way we understand.