Do voters update their perceptions of party positions? How certain do voters feel about their perceptions? We argue that perceptual updating and perceptual certainty depend on how divided or unified political parties are in their policy positions. We argue that voters do not accurately update their perceptions and that they become less certain about their perceptions when divided parties shift positions. For unified parties, we expect voters to accurately update party positions and become more certain about their perceptions. We test our arguments in the context of the European integration issue in the UK. Using original newspaper data on British parties’ messages on European integration and five waves of the British Election Study (2014–2016), we find evidence in support of our arguments. The paper has important implications for research on party position-taking and its consequences on voters.
