Who Can Deviate from the Party Line? Political Ideology Moderates Evaluation of Incongruent Policy Positions in Insula and Anterior Cingulate Cortex

Abstract

Political polarization at the elite level is a major concern in many contemporary democracies, which is argued to alienate large swaths of the electorate and prevent meaningful social change from occurring, yet little is known about how individuals respond to political candidates who deviate from the party line and express policy positions incongruent with their party affiliations. This experiment examines the neural underpinnings of such evaluations using functional MRI (fMRI). During fMRI, participants completed an experimental task where they evaluated policy positions attributed to hypothetical political candidates. Each block of trials focused on one candidate (Democrat or Republican), but all participants saw two candidates from each party in a randomized order. On each trial, participants received information about whether the candidate supported or opposed a specific policy issue. These issue positions varied in terms of congruence between issue position and candidate party affiliation. We modeled neural activity as a function of incongruence and whether participants were viewing ingroup or outgroup party candidates. Results suggest that neural activity in brain regions previously implicated in both evaluative processing and work on ideological differences (insula and anterior cingulate cortex) differed as a function of the interaction between incongruence, candidate type (ingroup versus outgroup), and political ideology. More liberal participants showed greater activation to incongruent versus congruent trials in insula and ACC, primarily when viewing ingroup candidates. Implications for the study of democratic representation and linkages between citizens' calls for social change and policy implementation are discussed.