Brain activation upon ideal-body media exposure and peer feedback in late adolescent girls

Abstract

Media's prevailing thin-body ideal plays a vital role in adolescent girls' body image development, but the co-occurring impact of peer feedback is understudied. The present study used functional magnetic resonance imaging (fMRI) to test media imagery and peer feedback combinations on neural activity related to thin-body ideals. Twenty-four healthy female late adolescents rated precategorized body sizes of bikini models (too thin or normal), directly followed by ostensible peer feedback (too thin or normal). Consistent with prior studies on social feedback processing, results showed increased brain activity in the dorsal medial prefrontal cortex (dmPFC)/anterior cingulate cortex (ACC) and bilateral insula in incongruent situations: when participants rated media models' body size as normal while peer feedback indicated the models as too thin (or vice versa). This effect was stronger for girls with lower self-esteem. A subsequent behavioral study (N = 34 female late adolescents, separate sample) demonstrated that participants changed behavior in the direction of the peer feedback: precategorized normal sized models were rated as too thin more often after receiving too thin peer feedback. This suggests that the neural responses upon peer feedback may influence subsequent choice. Our results show that media-by-peer interactions have pronounced effects on girls' body ideals.

Keywords: Adolescents; Body image; FMRI; Ideal-body imagery; Media effects; Peer influence; Self-esteem.

Fig. 1

Task sequence of congruent feedback (Color figure online)

Fig. 2

Neural responses in the contrasts (a) “participant rating: too thin vs. peer feedback: normal” compared to “participant rating: too thin vs. peer feedback: too thin” and (b) in the contrast “participant rating: normal vs. peer feedback: too thin” compared to “participant rating: normal vs. peer feedback: normal,” showing activation in bilateral insula and dmPFC/ACC; (c) “participant rating: normal vs. peer feedback: too thin” resulted in stronger activation in the ACC compared to “participant rating: too thin vs. peer feedback: normal” (all contrasts are displayed at FDR cluster-corrected threshold at p < .05 with an initial threshold of p < .005) (Color figure online)

Fig. 3

ROI plots of left insula, right insula, dmPFC/ACC, and self-esteem (Color figure online)