Auditory Isochrony: Time Shrinking and Temporal Patterns

Abstract

It has previously been reported that the duration of short time intervals is conspicuously underestimated if they are preceded by shorter neighbouring time intervals. This illusion was called 'time shrinking' and it was argued that it strongly affects the perception of auditory rhythms. In the present study this supposition has been pursued in three experiments. In the first, temporal patterns consisting of two, three, and four intervals had to be judged for anisochrony, which was invoked by offsetting the last sound from its isochronous position. By a constant method, it was determined that the last sound of fast sequences (50 ms base interval) had to be delayed by about 30 ms in order for isochronous rhythms to be perceived. Another interesting finding was that for sound sequences with base intervals up to 200 ms it was the difference limen, rather than Weber's ratio, that was constant for anisochrony detection. In the second experiment, the temporal patterns comprised two intervals, presented serially or separately. The deviation of isochrony could be on either the first or the second interval. The data, gathered by an adaptive method, showed time shrinking to be effective even up to a base interval of 200 ms. The third experiment involved a constant method and anisochrony was implemented on the first interval of two interval patterns. Time shrinking affected perceived isochrony in sequences with base intervals of 50, 100, and 200 ms. It is argued that the paradoxical results of anisochrony detection can be explained in terms of time shrinking. Some anomalies of rhythm perception and production that are the result of time shrinking are discussed.(ABSTRACT TRUNCATED AT 250 WORDS)

Discriminating time intervals presented in sequences marked by visual signals

“…As regards CE, the results might have taken two opposite directions.On the one hand, following ten Hoopen et al (1995), one might have expected more short responses for the comparison intervals, which were always presented after the standard(s). On the other hand, strictly speaking-that is, if Weber's law holds-a psychometric function should be positively skewed (Killeen et al, 1997).…”

“…As in ten Hoopen et al (1995), there was no feedback. Each session was divided into four blocks of 100 trials.…”

“…Each trial consisted of the presentation of three, four, or five visual signals marking two, three, or four intervals, respectively. This procedure follows ten Hoopen et al (1995; see their Experiment 1). The participants were asked to indicate, by pressing the appropriate button, whether the last interval (comparison) of the sequence was shorter or longer than the previous one(s), which was the standard (see Figure 1, upper panel).…”

“…It is noteworthy that psychometric functions in Experiment 1A and 1B were also fitted with the CND. If there is no increase of the difference thresholds with longer durations-as in ten Hoopen et al (1995), for instance-then a better fit for the data points on the psychometric functions should be provided by the CND model than by Equation 1. On the other hand, if Weber's law applies, a better fit should be expected from Equation 1 than from the standard Gaussian model.…”

Is subjective duration a signature of coding efficiency?

“…For example, increasing the luminance of an object (either physically or perceptually with brightness enhancement illusions) increases its perceived duration (Brigner 1986;Sperandio et al 2008). Conversely, reducing the visibility of a stimulus (as stimuli are during a saccade) leads to duration compressions ( Terao et al 2008).…”