Partisan animosity is asymmetrically driven by rising outgroup dislike rather than fading ingroup loyalty.

Evidence

We define partisan animosity as negative thoughts, feelings or behaviours towards a political outgroup. Notably, the term ‘partisan animosity’ involves only dislike of the outgroup and not positive regard towards the ingroup, which most of the studies we review do not measure. We chose this term because while it is unclear whether partisans like their own party more, they certainly report increasing dislike for the other party13. — Rachel Hartman et al., Interventions to Reduce Partisan…, 7

Categorization

• DEFINE: Clarifies partisan animosity as a unipolar construct — outgroup dislike without corresponding ingroup positivity — a precise definitional distinction that shapes measurement.
• XREF: Connects to affective polarization literature and the outgroup-derogation vs ingroup-favoritism distinction common in social identity research.
• QUESTION: Worth verifying whether the assumed asymmetry actually holds across newer datasets or is partly an artifact of which measures past studies chose to include.