Stimulus duration influences perceived simultaneity in audiovisual temporal-order judgment

Abstract

The temporal integration of stimuli in different sensory modalities plays a crucial role in multisensory processing. Previous studies using temporal-order judgments to determine the point of subjective simultaneity (PSS) with multisensory stimulation yielded conflicting results on modality-specific delays. While it is known that the relative stimulus intensities of stimuli from different sensory modalities affect their perceived temporal order, we have hypothesized that some of these discrepancies might be explained by a previously overlooked confounding factor, namely the duration of the stimulus. We therefore studied the influence of both factors on the PSS in a spatial-audiovisual temporal-order task. In addition to confirming previous results on the role of stimulus intensity, we report that varying the temporal duration of an audiovisual stimulus pair also affects the perceived temporal order of the auditory and visual stimulus components. Although individual PSS values varied from negative to positive values across participants, we found a systematic shift of PSS values in all participants toward a common attractor value with increasing stimulus duration. This resulted in a stabilization of PSS values with increasing stimulus duration, indicative of a mechanism that compensates individual imbalances between sensory modalities, which might arise from attentional biases toward one modality at short stimulus durations.

Effects of stimulus duration on audio-visual synchrony perception

“…Paired sample t tests showed no differences between PSS values of all three respective durations (t(16) = 1.24, p = .23, t(16) = .95, p = .36, t(16) = .42, p = .68). The constancy of mean PSS values with stimulus durations agrees with the results reported by Boenke et al (2009). In the high intensity condition, they found PSS values of about 20 ms for all conditions, whereas our results for the equalduration conditions are on average 7 ms smaller.…”

“…As proposed by Boenke et al (2009), the individual data of the 17 participants (Fig. 4) shortest stimuli).…”

“…For example, Roufs (1963Roufs ( , 1974 compared different synchrony adjustment methods and found that in both the audio-visual 'eye and ear method' as in the purely visual 'double flash method', the perception lag decreased for increasing intensities of the visual stimuli. Also, Boenke et al (2009) found a strong effect of intensity of the visual stimuli on audiovisual synchrony perception. From these results, the second explanation, in which the unimodal effects compensate for each other, seems to be more plausible.…”

“…The absence of an effect of stimulus duration on mean PSS estimates reported by Boenke et al (2009) can be Fig. 1 Expected duration effects on PSS in an audio-visual synchrony judgment task.…”

“…As far as we know, Boenke et al (2009) are the only researchers who have measured the effects of stimulus duration in an audio-visual synchrony perception task. In their experiment, participants made temporal order judgments for audio-visual stimuli with three different durations.…”