Prismatically induced curvature and finger-tracking pressure changes in a visual capture phenomenon

Abstract

A method was developed to help elucidate the manner in which vision exerts a dominant influence over other sources of sensory information. Subjects were required to track a horizontal straight edge with their forefingers while viewing the movements of their limbs through a curve-inducing lens. FiII'ger tracking pressure changes along the edge were transduced and monitored as a function of indtfced curvature orientation (convex-down, convex-up). Findings showed that greater pressure occurred when the finger was located at the low point(s) of the apparent curvature. A trend analysis indicated that the obtained pressure profiles (passive proprioception) contained large quadratic components and were exactly opposite in orientation to the shape of the visual image and subjects' reported felt curvature of the straight edge. Results were discussed in terms of central and peripheral interpretations of visual capture. In most real-life situations, humans process visual spatial information in larger amounts and with greater acuity than any other spatial information. A likely consequence is the experimental finding that when contlicting cues regarding spatial position are encountered by a subject, the resolution is preponderantly in the direction of the visual information in spite of the true state of affairs. Empirical contirmations of the so-called dominance of vision over the other senses have been widely