New research traces the physical roots of peer pressure and explains why rewards tend to outweigh risks when people are in a group

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PROBLEM: Showing off is tacky. Still, we tend to take stupid chances -- gamble more and engage in riskier behavior -- when all of our friends are watching. Why?

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METHODOLOGY: Researchers led by University of Southern California's Georgio Coricelli measured brain activity in regions associated with rewards and social reasoning using functional magnetic resonance imaging. They observed 24 participants who entered in lotteries.

RESULTS: The authors saw that the striatum, a part of the brain linked with rewards, showed higher activity when a participant beat a peer in the lottery, as opposed to when the participant won while alone. The medial prefrontal cortex, a region of the brain associated with social reasoning, exhibited similar patterns. Respondents who won in a group were also more likely to engage in riskier behavior in subsequent lottery trials.

CONCLUSION: The human brain places more value on winning in a social setting than it does on winning when alone.

IMPLICATION: We're not that different from other animals. There are strong incentives for wanting top social ranking, as animals in the dominant position use their status to secure privileged access to limited resources. Conversely, we're risk-averse when alone for reasons of survival as well. As Coricelli puts it, "In private environments with no social support network in place, a bad gamble can spell doom."

SOURCE: The full study, "Medial Prefrontal Cortex and Striatum Mediate the Influence of Social Comparison on the Decision Process," is published in the journal Proceedings of the National Academy of Sciences.

Image: REUTERS/Pablo Sanchez.