Two-point vibrotactile discrimination related to parameters of pulse burststimulus

Tactile spatial resolution is an important factor in the design of vibrotac tile arrays. The two-point discrimination distance is used as a measure of tactile spatial resolution. An experimental study is presented showing the effect of pulse burst stimulus parameters, pulse repetition period and duty cycle on two-point vibrotactile spatial discrimination. An array of piezoc eramic vibrators is used to measure two-point spatial discrimination on the index finger. In a group of 14 subjects, the average two-point discriminat ion distance for a pulse repetition period of 1/25s is 2.1 mm (SD = 1.0), w hereas for 1/500s it is 5.1 mm (SD = 0.9). Differences in discrimination di stances are statistically significant according to the ANOVA analysis (p<0. 001). Results show that the two-point discrimination distance is better for longer pulse repetition periods. Therefore the pulse repetition period in an excitatory waveform composed of bursts of pulses is important for tactil e resolution. No statistically significant differences in discrimination di stances are found between bursts of pulses of 50% duty cycle and those of l ower duty cycle. The latter result indicates that, by choosing low-duty cyc le waveforms for vibrotactile stimulation, the power can be reduced with no loss in two-point discrimination capacity.