• ideology;
  • need to evaluate;
  • political expertise;
  • attitude structure

Political psychologists have typically argued that ideological commitments are structured in a bipolar fashion, where a positive evaluation of conservative objects implies a negative evaluation of liberal objects (and vice versa). Individual differences in conformity to this pattern are usually attributed to an ability-related variable, i.e., political expertise. Departing from this strict focus on ability, this study examines the hypotheses that an important motivational variable—the need to evaluate, or the desire to form opinions of objects as “good” or “bad”—would (1) predict deviations from ideological bipolarity, even controlling for expertise; and (2) moderate the relationship between expertise and deviations from bipolarity. Data from two national surveys provided evidence for these hypotheses and indicated that the results extended to deviations from bipolarity in evaluations of presidential candidates and political parties.