Ipsilateral and contralateral masking of duration.

Abstract

Judgments of the durations of test tones that were preceded or followed by a masking tone were elicited; the test tones and masks were presented either to the same ear or to different ears of the listeners. On both forward- and backward-masking trials, percentages correct increased with increases in the silent interstimulus interval (ISI) between the test tone and mask, an effect that did not depend on whether the mask was presented ipsilaterally or contralaterally. In addition, with increases in the ISI and with increases in the mask duration, there was an increasing tendency for listeners to respond “long” to the test tone, irrespective of the actual duration of the test tone. These biases were generally greater on trials in which the mask was presented ipsilaterally. 1t is suggested that, when stimuli occur in close temporal proximity, the decreased percentages correct at short ISIs may reflect misassignment of pulses generated by an internal clock. In contrast, the biases that result from manipulations of lSI and mask duration may be due to later operations, such as those that occur at the level of very-short-term memory.