ADAPTING TO SUPERNORMAL AUDITORY LOCALIZATION CUES - II - CONSTRAINTSON ADAPTATION OF MEAN RESPONSE

A series of experiments was performed in which subjects were trained t o interpret auditory localization cues arising from locations differen t from their normal spatial positions. The exact pattern of mean respo nse to these alterations (as a function of time) was examined in order to begin to develop a quantitative model of adaptation. Mean response s were roughly proportional to the normal position:associated with the localization cues presented. As subjects adapted, the best-fit slope (relating mean response and normal position) changed roughly exponenti ally with time. The exponential rate and adaptation asymptote were fou nd for each subject in each experiment, as well as the rate and asympt ote of readaptation to normal cues. The rate of adaptation does not sh ow any statistical dependence on experimental conditions; however, the asymptote of the best-fit slope varied with the strength of the trans formation used in each experiment. This result is consistent with the hypothesis that subjects cannot adapt to a nonlinear transformation of auditory localization cues, but instead adapt to a linear approximati on of the transformation. Over time, performance changes exponentially towards the best-fit linear approximation for the transformation used in a particular experiment, and the rate of this adaptation does not depend upon the transformation employed. (C) 1998 Acoustical Society o f America.