, Volume 63, Issue 7, pp 1140-1152

The independence of size perception and distance perception


Research on distance perception has focused on environmental sources of information, which have been well documented; in contrast, size perception research has focused on familiarity or has relied on distance information. An analysis of these two parallel bodies of work reveals their lack of equivalence. Furthermore, definitions of familiarity need environmental grounding, specifically concerning the amount of size variation among different tokens of an object. To demonstrate the independence of size and distance perception, subjects in two experiments were asked to estimate the sizes of common objects from memory and then to estimate both the sizes and the distances of a subset of such objects displayed in front of them. The experiments found that token variation was a critical variable in the accuracy of size estimations, whether from memory or with vision, and that distance had no impact at all on size perception. Furthermore, when distance information was good, size had no effect on distance estimation; in contrast, at far distances, the distances to token variable or unknown objects were estimated with less accuracy. The results suggest that size perception has been misconceptualized, so that the relevant research to understand its properties has not been undertaken. The size-distance invariance hypothesis was shown to be inadequate for both areas of research.

Part of this research was reported in a doctoral dissertation by C.A.L. in 1990. Partial support for this research was provided by Research Grant NEI-07801 from the National Eye Institute to R.N.H. and by two research contracts from the Veterans Administration’s Rehabilitation Research and Development Program (C448-R and C995-PA) to the Rehabilitation Research and Development Center at the Hines VA Hospital, Hines, Illinois, and through contracts from the Hines VA Hospital to the University of Illinois at Chicago to R.N.H.