Datensatz

Zusammenfassung

Sensory modalities do not act in isolation; they can influence one another. One intriguing example is temporal ventriloquism, where auditory and visual signals presented asynchronously appear to be closer in time than they are generated. The characteristics of this perceptual phenomenon are still not completely defined. In particular, it is not clear whether the order of presentation has an influence on the effect, whether there are temporal grouping effects for other modalities, and whether this effect only occurs for certain asynchronies of the signals. This study aims to fill this lack of knowledge by investigating how crossmodal temporal grouping affects perceived duration when onset and offset of a stimulus are defined by signals of different modalities in all combinations of auditory, visual, and tactile stimuli. To test this, a two interval forced choice (2IFC) paradigm was used, where participants had to judge which of two intervals was shorter. One interval consisted of a lasting sound (filled interval), the other interval was defined by two signals of different modalities at the onset and offset (empty interval). These two signals could be auditory (beep), visual (flash of a LED) or tactile (vibration on the participants’ left index finger). Different stimulus onset asynchronies (SOA) between 100 and 900ms of the crossmodal interval were tested. Moreover, the order of the signals forming the empty interval was reversed. The duration of the filled interval was 30 to 170 of the duration of the empty interval. For each SOA of the empty interval, the point of subjective equality (PSE) for the duration was computed, which is the duration of the filled interval perceived to be equal to the empty interval. Results confirmed that for audiovisual intervals grouping effects were more salient with larger SOAs between the signals defining the empty interval. When the light preceded the sound grouping effects were also found for 500 and 700ms. For audiotactile intervals, instead, grouping effects occurred between 500 and 900ms but only when vibration preceded sound. Lastly, for visuotactile intervals, grouping occurred at SOA of 500ms but only when light preceded vibration. From these results, we can conclude that audiovisual temporal ventriloquist is only an instance of a more general crossmodal grouping effect that occurs with various modalities. Moreover, our data indicates that this effect acts differently on specific modality combinations. Temporal grouping is affected by both the time between the signals and their order of presentation.