Adaptation to supernormal auditory localization cues as a function of rearrangement strength

Abstract

The ability of humans to adapt to intermodal discrepancies is an important factor in the design of virtual environments and teleoperator systems. Previously, it was demonstrated that subjects can adapt to supernormal auditory localization cues that enhance position resolution using either standard psychophysical training methods (correct-answer feedback) or methods traditionally employed in studies of sensorimotor rearrangement (active sensorimotor loop tasks without special cognitive feedback). In the present study, the strength of the supernormal rearrangement was parametrically varied in order to ascertain the impact on the rate and asymptote of adaptation achieved. Subjects were repeatedly tested in a hybrid real/virtual environment where auditory stimuli were synthesized (using a PC, Convolvotron and electromagnetic head tracker) for thirteen positions in the horizontal plane marked by real lights. Testing consisted of identifying the azimuth of the virtual sound source without significant head motion, but with correct-answer feedback. Preliminary results will be given for resultant changes in bias and resolution as well as for rate and asymptote of adaptation as a percentage of the distortion caused by the rearrangement. [Work supported by MIT Lincoln Laboratory & AFOSR, Grant No. 90-200.]