Abstract
We examined the cross-modal effect of irrelevant sound (or disk) on the perceived visual (or auditory) duration, and how visual and auditory signals are integrated when perceiving the duration. Participants conducted a duration discrimination task with a 2-Interval-Forced-Choice procedure, with one interval containing the standard duration and the other the comparison duration. In study 1, the standard and comparison durations were either in the same modality or with another modality added. The point-of-subjective-equality and threshold were measured from the psychometric functions. Results showed that sound expanded the perceived visual duration at the intermediate durations but there was no effect of disk on the perceived auditory duration. In study 2, bimodal signals were used in both the standard and comparison durations and the Maximum-Likelihood-Estimation (MLE) model was used to predict bimodal performance from the observed unimodal results. The contribution of auditory signals to the bimodal estimate of duration was greater than that predicted by the MLE model, and so was the contribution of visual signals when these signals were temporally informative (ie, looming disks). We propose a hybrid model that considers both the prior bias for auditory signal and the reliability of both auditory and visual signals to explain the results.