Psychophysical characteristics of the auditory image movement perception during dichotic stimulation.

Dichotic stimulation with binaurally presented click trains at time-varying interaural differences of stimulation caused a pronounced sensation of fused image (FI) movement in man. Threshold click rate in the trains needed for the FI movement sensation during variations of interaural time differences of stimulation equalled 7.6 Hz and during variations of interaural intensity differences it equalled 9.6 Hz. When FI movement velocity ranged from about 20 to 120 degrees/s with changing interaural intensity of stimulation, differential threshold for FI movement velocity increased from 2 to 12 degrees/s. Relative differential thresholds of the perception of FI movement velocity were essentially independent of the velocity. Subjective scales of FI movement velocity perception could be basically approximated by linear relations y = AX, y = A(X-X0). The scale slopes appeared to be significantly different during fractionation and multiplication procedures.