may depend on the increased speed of processing form via sight. If we blur vision sufficiently, normal observers rely on touch ( Heller, 1983). Moreover, visual dominance may break down under circumstances where vision is blurry, as in peripheral vision, or in people with low vision. One would further expect that dominance relationships might shift for people undergoing progressive loss of a sense, as with a person losing sight or hearing.
This raises the question of the "normal observer." Most discussions of intersensory relations assume a "normal" observer. We have methods for testing this in sight, and norms are readily available for acuity, contrast sensitivity, and so on. Unfortunately, we don't have this information for touch. We really don't know what normal touch might be, and this greatly complicates any discussion of intermodal relations. It seems likely that just as there are myopic individuals, and those with poor hearing, there are people with poor touch. This is obvious when a person has neuropathy owing to diabetes, or has peripheral nerve damage. However, we don't even have a name for this sort of defect in the sense of touch. Thus, it becomes difficult to answer questions about which sense is most appropriate for perception of a particular attribute, when we can't assess a "normal" observer, and screen out people with "low touch."
Intermodal relations and perceptual saliency are not constant over the course of development. Newborn animals may be more likely to depend on cutaneous input ( Gottlieb, 1971). Furthermore, it is entirely possible that there is a shift in reliance on the mouth for exploration of objects to the hands in early infancy (see Turkewitz & Mellon, 1989). Bushnell and Boudreau have focused their discussion on the use of the hands for haptics, and perceptual saliency in early infancy.
Gottlieb G. ( 1971). "Ontogenesis of sensory function in birds and mammals". In E. Tobach, L. R. Aronson , & E. F. Shaw (Eds.), "The biopsychology of development" (pp. 67-128). New York: Academic Press.
Heller M. A. ( 1983). "Haptic dominance in form perception with blurred vision". Perception, 12, 607-613.
Rock I., & Victor J. ( 1964). "Vision and touch: An experimentally created conflict between the two senses". Science, 143, 594-596.