Temporal windows for signals presented at uncertain times.

Abstract

A temporal analog of the Greenberg and Larkin [J. Acoust. Soc. Am. 44, 1513–1523 (1968)] frequency probe technique was used to measure the temporal window for detection of temporally uncertain signals. Percent correct responses for a 20-ms, 1-kHz signal presented in broadband noise was measured using a fixed-level 2IFC procedure. On 68% of the trials, the signal was synchronous with an LED flash and a contralateral click; on the remaining trials, the signal was presented asynchronously. Performance was best when signals were synchronous with the marker cues, and deteriorated monotonically as the interval between the signal and marker cues increased. The temporal windows measured in this way had durations of approximately 175 ms measured between the −3-dB points, more than a factor of 3 shorter than those obtained by Leis-Rossio and Small [J. Acoust. Soc. Am. Suppl. 1 80, S92 (1986)] using a similar technique. This indicates that the observer is not using the high degree of temporal resolution of which he is capable, and suggests a strategy whereby processing effort or attention is distributed over time. In a companion resolution experiment, subjects were able to detect intervals of the order of tens of milliseconds between the signal and the marker especially when the signal preceded the marker, providing further evidence that temporal processing is specific to the particular task or listening procedure that challenges the observer. [Work supported by NIDCD DC00683.]