In-group as part of the self: In-group favoritism is mediated by medial prefrontal cortex activation

Abstract

Our identity consists of knowledge about our individual attributes (personal identity) as well as knowledge about our shared attributes derived from our membership in certain social groups (social identity). As individuals seek to achieve a positive self-image, they aim at comparing favorably with other individuals or their in-group comparing favorably with referent out-groups. Imaging data suggest a network centered on the medial prefrontal cortex (MPFC) to instantiate functions that are integral to the self, conceived as the personal self. Given that the social self is constituted by the same mechanisms as the personal self, we expect MPFC activation also for situations in which the social self is addressed, for instance when situations permit evaluative intergroup comparisons. Accordingly, participants worked on a modified version of the minimal group paradigm in the present functional magnetic resonance imaging experiment. Imaging data revealed activation within a network centered on the dorsal MPFC specifically for social identity processes. Furthermore, this activation showed correlation with the displayed in-group bias. The present findings show that social and personal identity processes draw on the same cerebral correlates and hence it is concluded that a network centered on the MPFC subserves functions integral to the self.

Keywords:

• Self-categorization
• In-group favoritism
• Medial prefrontal cortex
• Social comparison
• fMRI

Acknowledgements

The authors thank Tim Hodgson and two anonymous reviewers for helpful comments on an earlier draft as well as Eva Weig and Jennifer Kittel for their assistance in stimulus preparation and data collection. The results were presented at the 12th Annual Meeting of the Organization for Human Brain Mapping, Florence, Italy, 2006.

Notes

¹One may wonder why we did not calculate a correlational analysis between behavior and brain activity. Since we used second-level analyses of groups of subjects based on Bayesian statistics providing probability maps, a correlational analysis between a probability and a performance index is, in our opinion, difficult to interpret. Nevertheless, a correlational analysis of probability and intergroup behavior revealed basically the same activation pattern as observed with the median-split.

²Mean identification value of the four low-identifiers: 2.25 vs. 3.7 for the 16 high-identifiers, t(18) = − 7.22; p <.001.

³Due to the small sample size a more liberal threshold of 96.8% was applied.