The influence of theoretical knowledge on similarity judgment.

The similarity of the features between two entities has been assumed to be the essential factor for distinguishing these two entities across a variety of cognitive acts; however, the mechanism underlying the similarity processing remains unclear. The perceptual-based account suggests that similarity judgment is based on perceptual features between entities, whereas other accounts assume that similarity judgment relies heavily on one's previous knowledge of the entities. In Experiment 1, we explored the influence of theoretical knowledge on similarity judgment when perceptual features conflict with conceptual information. In Experiment 2, we examined whether categorization tasks further influence the results of the similarity judgment. Our results showed that the theoretical knowledge contributed to the overall similarity of the stimuli. In addition, carrying out a categorization task or not did not contribute more to the processes of the similarity judgment. Overall, these findings suggest that the conceptual information is more important than perceptual features while judging the similarity of two entities; if sufficient theoretical knowledge is available, the criteria for carrying out the categorization task might be consistent with those for the similarity judgment in the present study.