Abstract:
Prospective information, that is, present conditions of stimulation that are informative about a future state, e.g., the timing and/or location of an impending contact, is required for coordinating acts of interception and avoidance. In the present study, acoustic simulations of passing objects (at different speeds and distances) were produced by modulating the amplitude of a 1-kHz tone in accordance with the inverse square law of acoustic intensity. The simulations were used to explore listeners' capacity for auditorally anticipating arrival time simply on the basis of intensity change---formulated as a tau variable [see Shaw, McGowan, and Turvey, Ecol. Psychol. 3, 253--261 (1991)]. Subjects indicated either the arrival time of a single passing object or the first arrival within a pair by squeezing a dynamometer. Response accuracy/variability and anticipatory EMG, SCR, and EEG activity were used as indexes to listeners' ongoing awareness of object position during the simulated approach. Preliminary results indicate highly systematic accuracy and variability, along with the inadequacy of tau as a means of formalizing the relevant prospective information supporting anticipation.