2013年10月17日木曜日

Neural Evidence for Individual and Cultural Variability in the Social Comparison Effect

Pyungwon Kang, Yongsil Lee, Incheol Choi, and Hackjin Kim
J. Neurosci. 2013;33 16200-16208

fMRIを用いた文化差の研究。
アメリカ人と韓国人の比較。アメリカは「Independentな文化」の例、韓国は「Interdependentな文化」の例らしい。
Interdependentな文化で育った韓国人の方が(Independentな文化で育ったアメリカ人に比べ)、報酬系の脳部位(腹側線条体、腹内側前頭前皮質)が「自分と他者の報酬の違い」に敏感に反応した。

Although several studies have investigated the neural mechanism of social comparison, it remains unclear whether and how cultural membership, particularly independent versus interdependent cultures, may differentially shape the neural processes underlying social comparison. In the present functional magnetic resonance imaging (fMRI) study, we examined the behaviors and neural response patterns of Korean (i.e., interdependent culture) and American (i.e., independent culture) participants while performing a financial gambling task simultaneously and independently with a partner. Upon seeing the partner's income, greater modulation of the activity in the ventral striatum (VS) and the ventromedial prefrontal cortex (vmPFC) by relative gain was observed in Korean than American participants, suggesting greater sensitivity of Koreans toward social comparison. The strength of functional connectivity between the VS and the vmPFC predicted individual variability in the degree to which participants' decisions were affected by relative incomes. Additional model-based fMRI analysis further confirmed the primary role of the vmPFC in biasing decisions based on relative incomes. In summary, the present study provides the first neural evidence for decision biases due to social comparison and their individual and cultural variations.

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