Political Identity and Perceived Threat Predict Negative Perceptions of Outgroup Facial Expressions
Social group identity plays a central role in political polarization and inter-party conflict. Here, we use ambiguously valenced faces to measure affective biases in the processing of political in and outgroup faces and explore predictors of negativity toward political outgroups. Participants identifying as Democrats and Republicans categorized happy, angry, and surprised faces as positive or negative. Whereas happy and angry faces convey positive and negative valence respectively, surprised faces are ambiguous in that they readily convey positive and negative valence. Thus, surprise is a useful tool for characterizing bias. Face stimuli were assigned to the participants’ political in or outgroup, or a third group with an unspecified affiliation (baseline). Participants also completed measures of strength of political identification and perceived outgroup threat. We found a significant interaction of facial expression and group membership, such that outgroup faces were categorized more negatively than ingroup and baseline, but only for surprise. Strength of identification moderated the relationship between threat and the magnitude of outgroup negativity, such that increased outgroup threat predicted greater negativity towards the outgroup (relative to the ingroup), and this effect was exacerbated by stronger ingroup identification. There was also an interaction of facial expression and political affiliation, with Republicans categorizing surprise more negatively than Democrats across all group conditions. Our findings reinforce the importance of political identity on inter-party affective biases and are consistent with ideological differences in bias. Further, strength of political identification and perceived outgroup threat are established as potential mechanisms underlying political polarization and inter-party conflict.