Duration Discrimination of Intermodal Intervals

Abstract

<p>This research is an extensive investigation of the discriminability of brief intermodal temporal intervals. For intervals of less than 700msec., the level of performance is lower than that of intramodal intervals. In that range two psychophysical methods, Many-to-Few and Single Stimulus, give very different discrimination functions. However, the duration of the markers and the type of intermodal intervals are found not to be effective variables. An empirical relationship describing SD/DT75 as constant is shown to hold for a number of intra and intermodal psychometric functions.</p> <p>Two quantitative models developed to account for intramodal duration discrimination, describe very well intermodal discrimination in two experiments. Although none can be rejected, the onset-offset model is prefered because it represents better the totality of the results in this research. Finally, response latencies clearly indicate the operation of a real-time criterion mechanism in duration discrimination. It is concluded that duration discrimination is under the control of a single central timekeeper.</p>