Policy-based and Affective Partisanship Depend on Dissociable Neural Systems

Political partisanship is often conceived as a lens through which we view politics. Behavioral research has distinguished two types of “partisan lenses” - Policy-based and Affective – that may influence our perception of political events. Little is known, however, about the mechanisms through which partisanship operates within individuals. We addressed this question by collecting neuroimaging data while participants watched videos of speakers expressing partisan views. A “partisan lens effect” was identified as the difference in neural synchrony between each participant’s brain response and that of their partisan ingroup vs. outgroup. A policy-based partisanship lens effect was observed in socio-political reasoning and affective responding brain regions. An affective partisanship lens effect was observed in mentalizing and affective responding brain regions. These data suggest that policy-based and affective partisanship are supported by related but distinguishable neural and therefore psychological mechanisms, which may have implications for how we characterize partisanship and ameliorate its deleterious impacts.