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

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. Finger tracking pressure changes along the edge were transduced and monitored as a function of induced 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.