Two-Tactor Vibrotactile Navigation Information for the Blind: Directional Resolution and Intuitive Interpretation

Lacking vision, blind people have to exploit other senses for navigation. Using the tactile rather than the auditory sense avoids masking important environmental information. Directional information is particularly important and traditionally conveyed through an array of tactors, each coding one direction. Here, we present a different approach to represent arbitrary directions with only two tactors. We tested intuitiveness, plasticity, and variability of direction perception in a behavioral experiment in 33 seeing participants. Vibrotactile stimulation was applied to the palms of both hands. Directions were coded through the temporal structure of the stimuli. Three different codes were tested. Participants reported their directional percept by moving a marker on a computer screen. The participants' ability to interpret stimuli intuitively depended strongly on the direction code used. After an explanation of the code, participants generally performed well. When systematic deviations from linearity were accounted for, the mean accuracy of direction perception was around 150-200 and, depending on the code used, showed an improvement with practice. The results suggest that the neuroperceptual system is able to deduce directional information with reasonable resolution from temporally modulated vibrations even when only two tactors are used. This greatly improves the everyday usability of vibrotactile stimulation for directional information.