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A Positive Neural Payoff for Revenge?

Neural reward systems were activated as these men anticipated exacting revenge on those who violated group norms.

Why do humans exact revenge even at great personal cost? To explore the neurobiologic basis of these actions, investigators performed PET scans on men involved in a money-based game; the men contended with others who had violated group norms by acting in an untrustworthy manner ("defectors").

Among subjects who reported a desire to punish, PET scans demonstrated activation of areas in the dorsal striatum, particularly the head of the caudate nucleus, as they anticipated retaliating against defectors. This brain area has been associated with anticipated rewards or pleasures. Greater activation occurred when subjects could actually reduce the defector's payout (effective punishment, rather than merely symbolic). Concurrent activity of the medial prefrontal cortex, associated with cost-benefit analyses of behaviors, suggested that the rewards anticipated from vengeful behavior could override increased personal costs. Subjects with greater caudate activation when punishment had no personal cost were willing -- in scenarios that did involve personal cost -- to spend more of their own resources to punish the defectors.

Comment: These findings indicate that the "neuroeconomics" of altruistic punishment are apparently rooted in reward-related brain systems. It remains to be determined how much the neurobiologically based rewards associated with vengeful behavior are learned, culturally influenced, and/or genetically variable within populations. Understanding that neural reward systems may reinforce the anticipation of revenge -- even in the face of mounting costs -- may help us deal with human aggression in settings ranging from the clinical to the political. Functional MRI research (which, as a commentator points out, has greater sensitivity to timing than PET) may help further delineate the sequence of events.

— Joel Yager, MD

Published in Journal Watch Psychiatry September 23, 2004

Citation(s):

de Quervain DJF et al. The neural basis of altruistic punishment. Science 2004 Aug 27; 305:1254-8.

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• Medline abstract (Free)

Knutson B. Sweet revenge? Science 2004 Aug 27; 305:1246-7.

• Original article (Subscription may be required)
• Medline abstract (Free)