Illusory perception of auditory filled duration is task- and context-dependent.

Abstract

In filled-duration illusion, a continuous (long) tone or an auditory sequence with multiple clicks is typically perceived as longer than the same physical duration (i.e., empty interval) enclosed by two auditory clicks. The auditory sequence is composed of multiple empty intervals. However, the individual empty interval in an auditory sequence, compared with the empty interval presented alone, could be biased in duration perception. In the current study, we implemented five experiments to reveal that the time perception of a single empty interval versus that of (mean) empty intervals in an auditory sequence depends on the task demands and contextual information. Specifically, we observed that the empty interval (140ms) was perceived as longer than the same physical inter-stimulus interval in a sound sequence (Experiments 1 and 3). However, the empty interval (140ms) was perceived as shorter than a continuous beep (i.e., filled duration of 140ms) (Experiment 2). We observed a robust compression effect, in which the target empty interval (bounded by two oddball clicks) was perceived as shorter than the other physically equivalent intervals in a sound sequence (Experiment 4). In addition to the 'compression', perception of the target empty interval was assimilated by the other, task-irrelevant empty intervals in the sound sequence (Experiment 5). We explained the observed contextually modulated temporal illusions within a Bayesian inference framework.