Sexual orientation is associated with temporal changes in neural processing: An ERP study of in-group bias

Social biases have been demonstrated in many domains, including race, age, and sexual orientation. Behavioral research addressing sexual orientation identification has shown that individuals perform better than chance at recognizing the sexual orientation of others. Time processing for sexual orientation congruent and incongruent stimuli, based on participant self-report, was examined. A Neuroscan EEG system fitted with a 64-electrode cap was used to examine event-related potential P1, N170, P300, and LPP components in a sexual orientation identification/discrimination task. Undergraduates and young adults completed questionnaires regarding their own sexual orientation and then reported their best judgment on the sexual orientation for images of self-identified homosexual and heterosexual individuals. Analyses compared homosexual and heterosexual participants’ event-related potentials to heterosexual and homosexual faces. A greater vertex positive potential (VPP) was found for heterosexual individuals viewing heterosexual (in-group) stimuli compared to homosexual (out-group) stimuli. The N170 was reduced at P8 (right parietal site) for homosexual individuals viewing heterosexual faces. The late positive potential (LPP) was much smaller for heterosexual females viewing homosexual faces. These findings suggest greater amplitudes for congruent compared to incongruent stimuli based on sexual orientation for the VPP, N170, and LPP. However, incongruent faces elicited greater P300 amplitudes at P3 and P4. Results suggest that face processing differs as a function of own and other sexual orientation, providing a possible mechanism for group differences in sexual orientation identification previously found. These findings are consistent with in-group studies and support an expertise theory of face recognition.