Supportive but biased: perceptual neural intergroup bias is sensitive to minor reservations about supporting outgroup immigration.

While decreasing negative attitudes against outgroups are often reported by individuals themselves, biased behaviour prevails. This gap between words and actions may stem from unobtrusive mental processes that could be uncovered by using neuroimaging in addition to self-reports. In this study we investigated whether adding neuroimaging to a traditional intergroup bias measure could detect intersubject differences in intergroup bias processes in a societal context where opposing discrimination is normative. In a sample of 43 Finnish students, implicit behavioural measures failed to indicate intergroup bias against Middle Eastern and Muslim immigrants, and explicit measures reported rather positive attitudes and sentiments towards that targeted group. Yet, while implementing a repeatedly validated method for detecting intergroup bias, an implicit association paradigm presenting stereotypical ingroup and outgroup face stimuli while undergoing magnetoencephalography, we detected a clear neural difference between two experimental conditions. The neural effect is thought to reflect intergroup bias in the valence of the associations that faces evoke. The activity cluster of the neural bias peaked in BA37 and included significant activity in the fusiform gyrus, which has been repeatedly found to be active during face perception bias. Importantly, this neural pattern was driven by participants who were explicitly favourable of immigration - but to a lesser extent than others. These findings suggest that such variations in explicit support of immigration are associated with the differential neural sensitivity to the congruency of associations between intergroup faces and valence. This research showcases the potential of neuroimaging to unravel covert perceptual bias against outgroup members and its sensitivity to small variations in explicit attitudes.