In this paper we use comparative study of electoral systems data to understand the variation in citizens’ perceptions of political party placements on the left–right scale. We estimate multilevel models to assess the extent to which individual characteristics, party characteristics, and institutional designs contribute to variability observed in citizens’ perceptions of party placements. Because lack of information on the part of the citizens may be revealed through failure to respond to the left–right scale questions or through random components to actual placements, we develop models that include assessments of both types of responses to reduce bias from considering only one source. We find that individual-, party-, and institutional-level variables are relevant to understanding variation in citizens’ perceptions of party placements. Finally, we demonstrate that an inability to cognize the left–right scale (incognizance) and a deviation in the perceptions of party positions (perceptual deviation) have important consequences for citizens’ thermometer evaluations of political parties.