Information transmission with a multifinger tactual stimulator.

Abstract

The information transmission capabilities of a multifinger positional stimulator, called the Tactuator, were explored in a series of absolute identification experiments. Variations in the frequency of single sinewave stimuli evoked three relatively distinct perceptual attributes: smooth motion (up to about 6 Hz), a rough or fluttering sensation (about 10 to 70 Hz), and smooth vibration (above about 150 Hz). Multicomponent stimuli were formed by summing sinusoids from each of these three regions, with the intent that frequency (and amplitude) variations within each region could be identified independently. Stimulation was applied to either one of three digits (thumb, index, or middle) or to all three digits simultaneously. For stimulus durations of 500 and 250 ms, information transfer (IT) was 6.6 bits (corresponding to perfect identification of 97 stimuli); at 125 ms, IT was 6.0 bits. Estimates of potential IT rates were obtained by sequencing three random stimuli and (a) having the subject identify only the middle stimulus and (b) extrapolating this IT to that for continuous streams. Estimated IT rates were 13 bits/s, and the optimal stimulus presentation rate was approximately 3 items/s regardless of stimulus duration. This IT rate is roughly the same as that achieved by Tadoma users in tactual speech communication. [Work supported by NIDCD.]