Neural mechanisms of social influence

The present investigation explores the neural mechanisms underlying the impact of social influence on preferences. We socially tagged symbols as valued or not - by exposing participants to the preferences of their peers - and assessed subsequent brain activity during an incidental processing task in which participants viewed popular, unpopular, and novel symbols. The medial prefrontal cortex (mPFC) differentiated between symbols that were and were not socially tagged - a possible index of normative influence while aspects of the striatum (the caudate) differentiated between popular and unpopular symbols - a possible index of informational influence. These results suggest that integrating activity in these two brain regions may differentiate objects that have become valued as a result of social influence from those valued for non-social reasons. (C) 2009 Elsevier Inc. All rights reserved.