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Abstract

We report three experiments where the categorical perception of familiar, three-dimensional objects was investigated. A continuum of shape change between 15 pairs of objects was created
and the images along the continuum were used as stimuli. In Experiment 1 participants were first
required to discriminate pairs of images of objects that lay along the shape continuum. Then
participants were asked to classify each morph-image into one of two pre-specified classes. We
found evidence for categorical perception in some but not all of our object pairs. In Experiment 2 we
varied the viewpoint of the objects in the discrimination task and found that effects of categorical
perception generalized across changes in view. In Experiment 3 similarity ratings for each object
pair were collected. These similarity scores correlated with the degree of perceptual categorization
found for the object pairs. Our findings suggest that some familiar objects are perceived categorically
and that categorical perception is closely tied to inter-object perceptual similarity.