Amplitude and Duration Interdependence in the Perceived Intensity of Complex Tactile Signals

The dependency of the perceived intensity of a short stimulus on its duration is well established in vision and audition. No such phenomenon has been reported for the tactile modality. In this study naive observers were presented with pink noise vibrations enveloped in a Gabor wavelet. Characteristic durations ranging between 100 and 700 ms and intensities ranging from 0.3 and 3.0 10−3 m/s were presented to the fingertip. Using a two alternative forced choice staircase procedure, the points of subjective equivalence were estimated for the 400 ms long reference stimulus. Similarly to vision and audition, lower intensities were consistently reported for shorter stimuli. The observed relationship could be interpreted as reflecting a mechanism of haptic constancy with respect to exploration speed.