AMPLITUDE AND PERIOD DISCRIMINATION OF HAPTIC STIMULI

As part of a project to examine the ability of the hand to receive spe ech information, the present study examined subjects' ability to discr iminate finger movements along the dimensions of amplitude and period (movement duration). The movements consisted of single-cycle, sinewave movements and single-cycle, cosine movements presented to the index f inger. Difference thresholds were collected using an adaptive, two-int erval, temporal forced-choice procedure. Amplitudes from 6 to 19 mm we re examined, and the difference thresholds ranged from 10% to 18%. The thresholds were unaffected by the period of the movement. Periods fro m 3000 to 111 ms (0.33-9 Hz) were examined, and thresholds ranged from 6% to 16%. The thresholds were unaffected by the amplitude of the mov ement. Further measurements in which period was varied in the amplitud e discrimination task and amplitude was varied in the period discrimin ation task indicated that subjects were not using peak velocity as the basis for discrimination. These measurements were collected using a d isplay specifically designed for the examination of haptic stimulation and capable of presenting controlled patterns of movement and vibrati on to the fingers. (C) 1998 Acoustical Society of America.