How opinion variation among in-groups can skew perceptions of ideological polarization

There is a widespread perception that society has been polarizing into groups with increasingly divergent opinions. Multiple studies have sought to quantify the degree of opinion divergence (or ideological polarization), typically relying on differences between self-reported opinions, and have reached mixed conclusions. We propose this inconsistency can be explained by the way individuals' subjective perceptions are shaped by their social identities. We introduce a formal framework to analyze opinion data that accounts for such asymmetric, dynamic perceptions. When members of an in-group become increasingly homogeneous on a given topic (i.e. when the variance of opinions in that group decreases), they perceive deviant opinions as increasingly distant from their own. Consequently, these individuals may perceive greater polarization than an objective, neutral observer would. Applying the framework to data on the opinions of Germans about climate change, we show that perceived polarization may depend as much on the dynamics of in-group variance as it does on actual opinion divergence in society. Moreover, we show that the direction of this effect may vary over time and across different partisan groups. Our framework offers an explanation why people might sometimes perceive higher levels of ideological polarization than surveys indicate, independent of social segregation, polarization-enforcing cognitive biases, or affect-driven attitudes towards out-groups.