Research press release


Nature Neuroscience

How other people’s choices affect our own



Pearl Chiuたちは、賭け事課題の際に危険性の高い選択肢(確率は低いが見返りは大きい)と、安全な選択肢(確率は高いが見返りは少ない)とで決断を下す70名の被験者について、他人の選択を観察する場合としないで自分で決断する場合を比較研究した。被験者は、他人の選択を観察すると他人が以前に下したのと同じ選択をする傾向が強かった。他人の選択が被験者自身の危険性に対する好みに沿ったものであるとこの効果はいっそう強く、また危険性をきらう被験者は、他人の下す安全な選択に影響を受けやすいし、その逆も観察できた。別の実験でChiuらは、被験者が見た選択はコンピュータが無作為に生み出したものだと被験者に伝えた場合、危険性を伴う行動は影響を受けないことを発見した。


The decisions of other people similar to ourselves to take a risk or play it safe influence our own behavior by increasing the subjective value of a particular choice, reports a study published online in Nature Neuroscience. This finding increases our understanding of how social influences affect decision-making and could potentially guide efforts to alter individual decision-making via social factors.

Decisions about risky options are guided by both objective information, such as the likelihood of a particular outcome, and our attitudes towards risk. Other people’s decisions are known to influence our own choices of risker or safer options, but it is unknown how we incorporate them with our own preferences to make a decision.

Pearl Chiu and colleagues studied 70 human participants as they made decisions between risky (less probable, but higher payoff) and safe (more probable, but lower payoff) options in a gambling task, either on their own or after observing the choices of others. Participants were more likely to make a choice if they had observed that others had previously made the same choice. This effect was stronger when the choices of others were aligned with a participant’s own risk preferences: risk-averse participants were more likely to be influenced by another’s choice of a safe option, and vice versa. In a separate experiment, the authors found that risk-taking behavior was not affected when participants were told that a computer had randomly generated the choices they observed.

Using functional magnetic resonance imaging (fMRI), the researchers showed that the increased subjective value of an option due to social influence was reflected in activation of the ventromedial prefrontal cortex, an area known to encode the subjective value of choices.

doi: 10.1038/nn.4022

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