Neural evidence for inequality-averse social preferences

For richer, for poorer Based on experimental and field evidence, social scientists commonly assume that human behaviour favours outcomes that are 'fair', keeping inequality to a minimum since experience suggests that in the long run all will benefit. Now a novel role-play experiment in human male volunteers whose brain activity was being tracked by functional magnetic resonance imaging provides evidence for a neural basis for such 'inequality-averse' social preferences. The experiment starts with one of a pair of participants being made 'rich', receiving a large monetary payout; the other receives nothing and stays 'poor'. Neural responses in the striatum and prefrontal cortex of the 'rich' subjects were stronger when the other individual received further payments. In the 'poor' subjects, neural responses in the same areas were stronger when they themselves received the money. This suggests that the brain's reward circuitry is sensitive to distribution inequality and is actively modulated relative to context.