Research press release


Nature Neuroscience

Always look on the bright side of life


T Sharotらは、被験者に生活上の有害な出来事(例えば、アルツハイマー病にかかる、強盗に遭うなど)の一覧表を見せ、将来これらの出来事がどれくらい起こりそうかそれぞれ見積もらせた後、実際の統計的確率を提示した。最後に、被験者に同じ出来事の起こる見込みを再評価してもらい、実際の確率をフィードバックすることでその見積もりがどのように変化するのか評価した。



これらの結果から浮き彫りになるのは、ヒトの脳には「楽観バイアス」が生来備わっていると思われることで、このバイアスは世界に関する正確な 情報取得に対し抵抗する。

People update their beliefs accurately only when things turn out to be better than expected, not when they're worse than expected reports a study published online this week in Nature Neuroscience. Correspondingly, neural activity faithfully encodes feedback about things being better than previously thought, but the encoding of unexpectedly negative information is much weaker.

Tali Sharot and colleagues showed people a list of adverse life-events — such as getting Alzheimer Disease, or being robbed — and asked them to estimate how likely it was that these events would happen to them in the future. After each rating, people were provided with the actual probability of each of these events. Finally, these subjects rated the likelihood of the same events again, in order to measure how feedback about actual probabilities changes people's estimates of the likelihood of adverse life events.

The authors found that people were are far more likely to change their estimations later when the feedback indicated that, in reality, they were much less likely to suffer an adverse event than they had originally estimated. In contrast, when people were told that an adverse event was much more likely that they had originally estimated, they still tended to give the original, incorrect estimate.

The authors' team also tracked brain activity during this task, and, corresponding to the behaviour, they find that activity in frontal areas of the brain faithfully tracks estimation errors when things are better than expected, but its tracking of estimation errors when things are worse than people originally thought was much weaker.

These results highlight a seemingly built-in optimism bias in the human brain, which is resistant to accurate information about the world.

doi: 10.1038/nn.2949

「Nature 関連誌注目のハイライト」は、ネイチャー広報部門が報道関係者向けに作成したリリースを翻訳したものです。より正確かつ詳細な情報が必要な場合には、必ず原著論文をご覧ください。

メールマガジンリストの「Nature 関連誌今週のハイライト」にチェックをいれていただきますと、毎週最新のNature 関連誌のハイライトを皆様にお届けいたします。