Tactile Presentation of Visual Information

Psychophysical experiments on tactile sensations were performed to determine parameters needed in the design of a tactile display containing about one hundred stimulators. This tactile displayis being used to present spatial and temporal patterns to the skin to investigate the pattern recognition capabilities of the tactile sense. Airjet tactile stimulators were used in the experiments because they combine the fine localization property of poke-probe stimulators with the slight adaptation property of vibrators. Two perceptual phenomena that were investigated are apparent location and apparent motion. Apparent location occurs when two airjets of different pressure are sensed as one airjet located on the line connecting the two jets. Pressure difference and apparent location were found to be functionally related. This phenomena was extended to two dimensions with three noncollinear stimulators. Apparent motion occurs when two airjets with different onset times are sensed as one airjet moving between two locations. This phenomenon was found to occur when there was a 0.05-to 0.15-second time difference between the onsets of the two pulses, provided that the pulses overlap by less than 0.2 second. The system used to program the array of approximately 100 tactile stimulators is described.