An fMRI study on the neural correlates of social conformity to a sexual minority

Abstract

Social conformity refers to the tendency to align one's own behaviors, beliefs and values to those of others. Little is known about social influence coming from a minority group. To test whether social pressure from sexual minorities triggers avoidance-motivated behaviors, we explored how being influenced by the preferences of gay peers modifies the behavioral and neural reactivity of individuals defined as in- vs. out- groups on the basis of sexual orientation. To this aim, we combined fMRI with a social conformity paradigm in which heterosexual and gay/bisexual (hereafter non-exclusively heterosexual, NEH) individuals provided with male body attractiveness ratings by a fictitious group of gay students may or may not alter their previous rating and may or may not conform to the mean. Behaviorally, conformity to the minority preference was found in in-group NEH more than in out-group heterosexuals. Analysis of BOLD signal showed that social pressure brought about increased brain activity in frontal and parietal regions associated with the detection of social conflict. These results show that members of a sexual majority group display a smaller level of conformity when a sexual minority group exerts social influence. However, the neural correlates of this modulation are yet to be clarified.

Figure 1

Schematic representation of the experimental task. Structure and timeline of a representative event-trial from the male body attractiveness-rating task. Virtual models were created by the authors (see Visual Stimuli for details).

Figure 2

Behavioral results. The plot represents the interaction between Social influence (from −3 to +3) and Group (Het = Heterosexuals, NEH = Non-exclusively heterosexuals) in determining the difference between the first and the second attractiveness rating (Delta). Light blue shades represent 95% confidence bands, rugs represent the number of observations for each value.

Figure 3

Whole brain Social Influence effects (Disagreement vs. Agreement). Whole brain activation for the Disagree vs. Agree contrast displayed in the axial and coronal section. The bar plots at the bottom show the means and the 95% Confidence Intervals for the contrast estimates for the Disagree – Agree contrast in each group. The bar graphs are overlaid with the single data points.