Or consider a recent study by Abigail Marsh and her colleagues, of people who choose to donate their kidneys to strangers. Consistent with my argument, these exceptionally altruistic individuals do not score higher on standard empathy tests than normal people. But they are different in another way. The researchers were interested in the amygdala—a part of the brain that is involved in, among other things, emotional responses. Their previous research had discovered that psychopaths had smaller than normal amygdalae and lessened response when exposed to pictures of people who looked frightened,
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