Pattern identification and perceived stimulus quality as a function of stimulation waveform on a fingertip-scanned electrotactile display

The effect of stimulation waveform on pattern perception was investigated on a 49-point fingertipscanned electrotactile (electrocutaneous) display. Waveform variables burst frequency (F), number of pulses per burst (NPB), and pulse repetition rate (PRR) were varied in a factorial design. Contrast reduction was used to limit performance of perceiving a 1-tactor gap defined within a 3 * 3 tactor outline square. All three variables accounted for significant variations in performance with higher levels of F and NPB and lower levels of PRR, leading to better performance. In addition, we collected qualitative data on each waveform, and the qualitative differences were related to performance (e.g., waveforms perceived as having a more localized sensation were correlated with better pattern identification performance than those waveforms perceived as more broad). We also investigated the effect of stimulation contrast on pattern perception.