Weighting common and distinctive features in perceptual and conceptual judgments

By adding the same component (e.g., glasses) to two stimuli (e.g., schematic faces) or to one stimulus only, it is possible to assess the impact of that component as a common or as a distinctive feature. A formal procedure, based on the contrast model (A. Tversky, 1977, Psychological Review, 84, 327-352), for estimating the relative weight of common to distinctive features from similarity judgments between separable stimuli with independent components, was developed. The results show that in verbal stimuli (e.g., descriptions of persons, meals, trips) common features loom larger than distinctive features. On the other hand, in pictorial stimuli (e.g., schematic faces, landscapes) distinctive features loom larger than common features. Verbal descriptions of pictorial stimuli were evaluated like other verbal stimuli and unlike their pictorial counterparts. In conceptual comparisons, the relative weight of common to distinctive features was higher in judgments of similarity than in judgments of dissimilarity.