Testing the reinforcement learning hypothesis of social conformity. Issue 5 (27th November 2020)

• Record Type: Journal Article
• Authors: Levorsen, Marie; Ito, Ayahito; Suzuki, Shinsuke; Izuma, Keise
• Is Part Of: Human brain mapping. Volume 42:Issue 5(2021)
• Page Start: 1328
• Page End: 1342
• Publication Date: 2020-11-27
• Subjects: fMRI -- MVPA -- prediction error -- reinforcement learning -- social conformity; Brain mapping -- Periodicals; 611.81
• DOI: 10.1002/hbm.25296
• Languages: English
• ISSNs: 1065-9471

Abstract

Abstract: Our preferences are influenced by the opinions of others. The past human neuroimaging studies on social conformity have identified a network of brain regions related to social conformity that includes the posterior medial frontal cortex (pMFC), anterior insula, and striatum. Since these brain regions are also known to play important roles in reinforcement learning (i.e., processing prediction error), it was previously hypothesized that social conformity and reinforcement learning have a common neural mechanism. However, although this view is currently widely accepted, these two processes have never been directly compared; therefore, the extent to which they shared a common neural mechanism had remained unclear. This study aimed to formally test the hypothesis. The same group of participants ( n = 25) performed social conformity and reinforcement learning tasks inside a functional magnetic resonance imaging (fMRI) scanner. Univariate fMRI data analyses revealed activation overlaps in the pMFC and bilateral insula between social conflict and unsigned prediction error and in the striatum between social conflict and signed prediction error. We further conducted multivoxel pattern analysis (MVPA) for more direct evidence of a shared neural mechanism. MVPA did not reveal any evidence to support the hypothesis in any of these regions but found that activation patterns between social conflict and prediction error in these regions were largely distinct. Taken together, the present study provides no clear evidence of a common neural mechanism between social conformity and reinforcement learning. Abstract : The present study tested the hypothesis that social conformity would share the same neural mechanism as reinforcement learning. While univariate results showed large activation overlaps in the posterior medial frontal cortex (pMFC), anterior insula, and striatum between social conflict and prediction error, multi‐voxel pattern analysis (MVPA) showed that their activation patterns within each of these regions were largely distinct rather than similar. The results suggest that the idea that social conformity and reinforcement learning share common neural mechanisms may be too simplistic.