INTERMODALITY RELATIONS: VISION AND TOUCH
D. H. Warren M. J. Rossano University of California, Riverside
The guiding premise of this chapter is that in order to understand the sense of touch, one must consider the possibility that tactual perception is not entirely independent of vision. Thus the question to which this chapter is addressed is the following: What must we know about the relationship between vision and touch in order to understand touch?
A priori, there are several possibilities for potential interactions. First, vision and touch may be capable of processing the same or similar events, but they may do so largely independently of one another, with little or no interaction. Second, for some events, vision may mediate better perception than touch, and may, when information is available to both modalities, supersede touch entirely. Third, the reverse may happen. Finally, vision and touch may be differentially suited for different events and may interact in various ways, depending on the nature of the perceptual performance that is involved. For example, vision may add substantially to the quality of localization of tactual targets but may contribute little to the tactual discrimination of texture. To skip to the "bottom line," this fourth possibility best describes the literature--the interactions are complex and interesting, and they do not submit to simple conclusions.
One does not have to search very far for instances of the interactions of touch with vision. For example, if for some reason the tactual and visual systems provide different information to the observer about the size of an ob