Pattern identification as a function of stimulation on a fingertip-scanned electrotactile display

Two studies were conducted to determine the effect of stimulation current on pattern perception on a 49-point fingertip-scanned electrotactile (electrocutaneous) display. Performance increased monotonically from near chance levels at the lowest subthreshold current levels tested to approximately 90% at the highest comfortable current levels. This suggests the existence of a tradeoff between spatial performance and usable "gray scale" range in electrotactile presentation of graphical information.