Research press release


Nature Neuroscience

Adults with autism overestimate changeability of their surroundings



今回の研究でRebecca Lawsonたちの研究グループは、ASDの成人(24名)と年齢と知能指数が一致する神経学的機能が正常な成人(25名)の双方に学習課題を行わせ、その成績データにコンピューターモデリングを適用して、それぞれの被験者の学習過程の特徴を明らかにした。ここから分かったのは、自閉症の成人が知覚環境の変動性を過大評価する傾向があり、そのために適応的な驚きをもたらす安定した予想を形成するための学習が損なわれていることだった。つまり、キーボード上のキーを押した後、自動車のクラクションの音が聞こえても自閉症の成人は驚かない可能性があるのだ。Lawsonたちは、今回の研究で、ASDの患者がその環境の変化に応答する過程における行動的機構、計算的機構、生理的機構に関する新たな手掛かりが得られたと結論づけている。

Adults with autism spectrum disorder (ASD) show less surprise than adults without ASD when faced with something unexpected in their environment, and the level of this reduced surprise can predict the severity of ASD symptoms, reports a study published online this week in Nature Neuroscience. The study suggests that adults with ASD tend to overestimate how changeable an environment is and underestimate the likelihood of a specific change, thus making unexpected events less surprising.

Insistence on sameness and intolerance of change are part of the diagnostic criteria for ASD, but there is little research addressing how people with ASD represent and respond to changes to their environment. For instance, how surprised should a person be if they hit a key on their keyboard and hear a car-horn sound instead of a clacking sound- Ordinarily, the clacking sound would be expected, but if the person’s tech-savvy prankster teenage niece has been visiting, the person might adjust their expectations, owing to a more changeable (volatile) environment, and be less surprised. However, overestimating how changeable the environment is may impair the formation of prior expectations (of the key clack), thus making the car horn less surprising.

In this study, Rebecca Lawson and colleagues tested 24 adults with ASD and 25 age- and intelligence-matched neurotypical adults with a learning task and applied computational modelling to the data to characterize each person’s learning process. They find that adults with autism show a tendency to overestimate the volatility of the sensory environment, at the expense of learning to build stable expectations that lead to adaptive surprise. That is, after pressing a key on a keyboard, adults with autism might not be surprised by hearing a car horn. The authors conclude that their study offers novel insight into the behavioural, computational and physiological mechanisms that underlie how people with ASD to respond to changes to their environment.

doi: 10.1038/nn.4615

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