The proposed research will investigate the perception of tactile patterns by human subjects. The tactile patterns will be generated on arrays of stimulators that fit against the subject's fingertips. Each array consists of 144 stimulators arranged in a matrix 6 columns by 24 rows. Sets of patterns differing along such dimensions as location, intensity, number of line segments, and so forth will be generated and presented to subjects. Response measures will include identification, discrimination, reaction time, and pattern matching. Three aspects of tactile pattern perception will be examined: masking, interactions among multiple sites of stimulation, and the role of experience. A temporal masking paradigm will be used to see how the perception of tactile patterns is interfered with by tactile maskers and how the nature of the interference changes with changes in the type of masker and in the temporal separation between target and masker. In the studies of interaction among multiple sites, patterns will be presented to as many as three sites on the fingertips and palm. This paradigm will be used to assess the role of attention in tactile information processing. The role of short-term experience will be examined by measuring changes in pattern perception as subjects learn to identify and discriminate tactile patterns. The effect of long-term experience will be evaluated by comparing the performance of groups of subjects who differ in the amount and nature of their experience with complex tactile patterns. One group will be Optacon users, blind individuals who can read by means of a tactile array. The other groups will be blind individuals without Optacon experience and several groups of sighted subjects with varying amounts of tactile experience. The proposed research will be concerned with drawing parallels between tactile processing and visual and auditory processing, with developing measures relevant to understanding the neural coding of tactile patterns, and with improving cutaneous communication systems for the blind, deaf, and deaf-blind.
