Polarized neural responses to political narratives are sensitive to small variations in self-reported political perspectives

In an increasingly polarized and divided world, people often interpret new information through an ideologically biased lens (e.g., confirmation bias). Recent studies in the emerging field of political neuroscience report the phenomenon of "neural polarization": cerebral activity that is shared (synchronized) between individuals holding similar political perspectives - but not between those holding dissimilar perspectives. Here, we extend this literature by testing for neural polarization between people with subtly different ideologies. Using functional magnetic resonance imaging (fMRI) while individuals (<i>n</i> = 40) listened to narratives about immigration in Finland, we observe neural polarization between more and slightly less immigration-supportive individuals in widespread neural areas, similar to the areas reported in previous studies of neural polarization. The findings extend current knowledge by revealing that neural polarization arises even when self-reported ideological perspectives differ only slightly. Together, these results shed light on how political information is interpreted and processed in the brain.