Is virtue really its own reward? When it comes to altruism, the brain seems to pat itself on the back. The choice to cooperate stimulates pleasure centers in the brain and can even overcome the urge to strive for increased financial gains. This reward circuitry may provide a biological basis for altruism, selfless behavior that is unique to humans.
Researchers at Emory University scanned the brains of 36 women as they played Prisoner's Dilemma, a game that pits two subjects against each other and has been used in the study of social behavior for at least half a century. Subjects were rewarded money based on their choice to defect or to cooperate: A defection resulted in greater financial gain, while cooperation activated areas of the brain linked to the processing of pleasures such as drugs and food. Researchers also paired subjects with a computerized partner, but cooperation in this instance stimulated only one region of the brain, as opposed to the three distinct areas involved in positive human interactions.