Many theories of object categorization assume that objects
are represented in terms of components-attributes such as
parts, functions and perceptual properties. The origin of
these components has been neglected in concept learning
theories. W e provide further evidence for a theory of part
ontogeny in which parts are not simply given by
perceptual information but develop over the course of
category learning. T w o experiments are reported. T h e
experiments showed that subjects could identify a
component of u n k n o w n stimuli as a part in spite of
variation in its shape across exemplars of the category.
However, the experiments also revealed perceptual
constraints on what variations could be identified as the
same part.
