ASA 127th Meeting M.I.T. 1994 June 6-10

4pPP22. The influence of temporal deviations on the perception of auditory pattern components.

Gary R. Kidd

Dept. of Speech and Hear. Sci., Indiana Univ., Bloomington, IN 47405

Previous studies of the effect of deviations from pattern-based temporal expectations revealed increases in detection and discrimination thresholds for temporally displaced components in sequences of tones as the amount of displacement was increased [G. R. Kidd, J. Acoust. Soc. Am. 93, 2315(A) (1993)]. Further studies have examined a variety of temporal contexts to determine the conditions necessary for the establishment of an effect of deviation from temporal expectations. Expectations were induced by repeated presentations of a standard pattern on each trial. Temporal deviations were introduced in comparison patterns by advancing or delaying the onset of a single ``target'' tone while maintaining the temporal relations among the context tones. The effect of temporal deviations was found to be considerably more robust for frequency discrimination than for detection. Frequency discrimination was consistently more sensitive to small temporal displacements and large effects were obtained in rhythmic contexts that produced little or no effect on detection. The results suggest a rhythmic heightening of attention, based on pattern timing, that enhances resolving power for events within a fairly narrow temporal window. Alternative explanations for the greater sensitivity of frequency discrimination to temporal deviations will be evaluated. [Work supported by NIH.]