Differing approaches to two-dimensional shape recognition.

This article reviews a number of approaches that perceptual psychologists have taken in attempting to understand 2-dimensional (2-D) shape recognition. Various strands in the literature are traced and current theoretical accounts are discussed in light of the earlier work. Today, it is generally accepted that the internal representation of shape is in the form of a structural description. Such a description is, in turn, couched in some form of abstract code. There is increasing interest in the notion that structural descriptions are critically determined by the imposition of a frame of reference. Although the discussion primarily deals with work on 2-D shapes, the underlying assumption is that this work is fundamental for theories of visual object recognition.