Problems in perceptual development

The perceptual repertoire of human beings develops over a lengthy period of time. In maturity the spatial senses operate in such a way as to afford a veridical account of the physical environment. The reliability of sensori-motor behaviour and the accuracy with which spatial judgements can be made testify strongly to this. When required to process information of certain kinds, however, distortions are evidenced. Straight lines appear curved, regular forms are misshapen and forms of similar shape seem different. Thus, the spatial senses which allow reliable judgements to be made of some spatial patterns fall to do so when faced with others. The most convincing theories proposed to account for distortions of this kind are based upon the assumption that experience of typical features of the spatial environment serves to modify perceptual organisation. An experimental and theoretical appraisal is made of the 'perspective ' theory, the 'carpentered world' hypothesis and the 'size-constancy' theories in particular and the 'inappropriate size-depth' theories in general. The conclusion drawn is that these attempts to explain the development of perceptual organisation are unsuccessful.