Tactile apparent movement: the effects of shape and type of motion.

Abstract

Judgments of tactile apparent movement were obtained from six subjects for a variety of tactile spatiotemporal stimulus patterns (moving points and lines, rotating lines, and expanding squares, boundaries, and holes). Each of these patterns was presented by means of three different numbers of steps used to trace the pattern over time. Stimulus duration and interstimulus onset interval (ISOI) were varied to determine the temporal conditions required for good tactile apparent movement. In general, pattern shape and type of movement (linear, rotating, expanding) had little effect on the temporal conditions for good apparent movement or on the interactions among the other variables. Increasing the number of steps in a pattern decreased the ISOI required for good apparent movement, but had no effect on the range of ISOIs over which good movement was obtained. Increases in stimulus duration increased the ISOI required for good tactile apparent movement, in agreement with earlier studies, and increased as well the range of ISOIs over which good movement was obtained.