Vibrotactile forward masking: evidence for channel independence

Threshold shifts for the detection of vibrotactile test stimuli were determined as a function of the intensity of a masker. A 50-ms sinusoidal test stimulus was applied to the thenar eminence of the hand 25 ms after the termination of a 700-ms sinusoidal masker applied to the same site. The intensity of the masker was varied over a range of 0-44 dB SL. The frequency of the masker was either 15 or 250 Hz and the frequency of the test stimulus was either 15, 25, 100, or 250 Hz. The results support the hypothesis that the detection of vibrotactile stimuli is mediated by at least two receptor systems which do not mask each other.