The role of expectations in comparisons.

Expectations are proposed as a unifying framework for explaining a variety of findings on comparative judgment. Expectations may pertain to either the features of each separate object or their simultaneous occurrence in all relevant objects. Two experiments demonstrate that inducing expectations by varying the frequency with which a component occurs, as well as the frequency with which it is shared by the compared objects, results in augmented weighting of unexpected components. Expectations can arise not only from experienced frequencies but also from an inferred set of alternatives. Features of cohesive stimuli are shown to be more expected than features of noncohesive stimuli, in the latter sense. The relatively higher weighting of distinctive features in cohesive stimuli, as well as the higher weight assigned to structurally aligned differences, could thus reflect modifications in feature expectedness. Further experiments show how task-dependent weighting interacts with expectations to produce asymmetries between similarity and difference judgments. Finally, it is argued that changes in expectations regarding objects' attributes can explain context effects across different domains, including some types of preference reversals.