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Exp Brain Res (2007) 182:379385 DOI 10.1007/s00221-007-0992-2
RESEARCH ARTICLE
Assessing the neural correlates of self-enhancement bias: a transcranial magnetic stimulation study
Virginia S. Y. Kwan Veronica Barrios Giorgio Ganis Jamie Gorman Claudia Lange Monisha Kumar Alejandro Shepard Julian Paul Keenan
Received: 30 December 2006 / Accepted: 16 May 2007 / Published online: 3 July 2007 Springer-Verlag 2007
Abstract Considerable research has focused on overly positive self-perceptions (self-enhancement), and yet little is known about the underlying neural mechanisms. The present study sought to assess the neural correlates of self-enhancement by applying Transcranial Magnetic Stimulation (TMS) to three brain regions. Twelve participants rated their best friend, as well as the self on a set of desirable or undesirable traits while TMS pulses were delivered in a virtual lesion manner. During the baseline condition (Sham TMS), participants produced more desirable and fewer undesirable ratings for themselves as compared to their best friend, showing self-enhancement. Compared to Sham TMS, TMS delivered to the Medial Prefrontal Cortex (MPFC) reduced self-enhancement whereas TMS delivered to the Supplementary Motor Area (SMA) and the precuneus
did not. Together, these Wndings suggest that the MPFC may inXuence self-enhancement.
Keywords Medial prefrontal cortex Transcranial magnetic stimulation TMS Self-enhancement Self-deception Self-perception
Introduction
Little is known about the neural mechanisms underlying overly positive self-evaluations (i.e., self-enhancement bias), despite the numerous studies that have been carried out on self-enhancement and its relation to mental health (e.g., Bonanno et al. 2002; Colvin et al. 1995; John and Robins 1994; Kwan et al. 2004; Paulhus 1998; Sedikides et al. 2004; Taylor et al. 2003). However, both functional neuroimaging studies and those examining patient populations have indicated a possible role for positive self-biasing in the Medial Prefrontal Cortex (MPFC).
While there have been no direct, speciWc measures of the neurological correlates of self-enhancement bias, there is growing evidence that the functional brain networks involved in processing self-related information involve the MPFC in the evaluation of the self. SigniWcant MPFC involvement has been found during self-evaluation (Craik et al. 1999; Fossati et al. 2003; Johnson et al. 2002; Lou et al. 2004; Ochsner et al. 2005) and general self-reXection (Gusnard and Raichle 2001; Lieberman et al. 2004). For example, Ochsner et al. (2005) examined the neural correlates of directed (how you perceive...