Neural systems of social comparison and the "above-average" effect.

Extant neural models of self-evaluation are dominated by associations with medial prefrontal cortex (MPFC) and posterior cingulate cortex (PCC) function and have mostly been developed from studies differentiating self-evaluation from evaluation of other people. Although self-evaluation is robustly characterized by systematic biases, current neural models of self-evaluation cannot speak to their neurobiology because of a lack of research. The few extant studies have made claims about associations between bias and ventral anterior cingulate cortex (vACC) function but have confounded bias with the valence of experimental stimuli. In study 1, fMRI was used to examine the neurobiology of the "above-average" effect, a robust self-evaluation bias. The majority of people judge their personality to be more desirable (i.e., more positive and less negative traits) than their peers' personalities. MPFC and PCC were significantly more activated by a condition that reduced susceptibility to "above-average" judgments. However, MPFC and PFCC activity were not modulated by individual differences in "above-average" judgments. VACC activity distinguished positive from negative valence but did not predict individual differences in "above-average" judgments. Instead, the extent to which participants viewed themselves as "above average" was negatively correlated with orbitofrontal cortex (OFC) and, to a lesser extent, dorsal anterior cingulate cortex (dACC) activation. A complementary study found that mental load increases "above-average" judgments (study 2). These findings are the first to directly examine the neural systems involved in social judgment bias and have implications for the association between frontal lobe dysfunction and poor insight. Copyright (c) 2009 Elsevier Inc. All rights reserved.