Partisan in-group bias before and after elections

Partisan attachment is a major source of group identity in democracies, accounting for a strong in-group bias when citizens make judgments on trust, cooperation, and resource sharing. Yet what factors condition behavioural expressions of partisan in-group bias are not well-understood. Here, I explore the impact of one theoretically-critical factor - election cycles - in fueling partisan-based discrimination and favouritism. Using an experiment embedded in a panel study fielded immediately before and after the 2015 Canadian federal election, I find that pre-election in-group bias levels were cut by a full third within two days of election day. The bulk of the decline is explained by a decrease in willingness to discriminate against out-partisans, while co-partisan favouritism levels remain stable. Further, in-group bias substantially decreases post-election among supporters of gaining parties and among strategic voters, while losing party supporters and sincere voters continued to express it strongly. I discuss theoretical implications on our current, static understanding of partisan-based discriminatory behaviour.