Duration discrimination of noise bursts presented at a rapid rate

Abstract

The influence of the presentation rate of two noise bursts on the discrimination of duration was assessed using an adaptive two-alternative, forced-choice procedure. The time difference required for reliable discrimination was determined for 70 dB SPL noise bursts of 25-, 50-, 100-, 200-, 400-, 800-, and 1600-ms duration. The interval between the presentation of the two noise bursts in each trial was set at either 50, 200, or 1600 ms. The Weber fraction, Δt/t, was determined by an interaction between the noise duration and the rate of presentation. With a presentation interval of 1600 ms, Δt/t was a constant of 0.08 at all noise durations. Presentation intervals of 50 and 200 ms produced Δt/t functions which were elevated for short noise durations, but converged on the 0.08 Δt/t performance level with noise duration of 1600 ms. The Δt/t for a 25-ms signal was 0.30 with a 50-ms presentation interval, and 0.22 with 200 ms between noise bursts. The results are discussed in relation to neural constraints on the timing of rapidly presented stimuli. [Work supported by NSERC.]