Autor(es):
Santos, Jorge A. 
; Silva, Carlos ; Mendonça, Catarina
Data: 2011
Identificador Persistente: http://hdl.handle.net/1822/15848
Origem: RepositóriUM - Universidade do Minho
Detalhes do Documento
Motion in depth : audiovisual synchrony perception of walkers as a function of ...
Descrição
Audiovisual perception is still an intriguing phenomenon, especially when we think about the physical and neuronal differences underlying the perception of sound and light. Physically, there is a delay of ~3 ms/m between the emission of a sound and its arrival to the observer. On the other hand, we know that acoustic transduction is a fast process (~1ms) (Coney & Hudspeth, 1979), while phototransduction takes only ~50 ms (Lamb & Pugh, 1992). However, audio and visual stimuli that are temporally mismatched can be perceived as a coherent audiovisual stimulus (Point of Subjective Simultaneity – PSS), but a sound delay is often necessary in order to achieve a better perception of audiovisual synchrony (e.g. Alais & Carlile, 2005; Sugita & Suzuki, 2003). A PSS that requires a sound delay can be evidence for a perceptual mechanism that either accounts for physical differences or for a mechanism that compensates for the difference in transduction times between sound and light. In this study, we analyze PSS as a function of stimulus distance to understand if individuals take into account sound velocity or if they compensate for differences in transduction time when judging synchrony. Using Point Light Walkers (PLW) as the visual stimulus and sound of steps as the audio stimulus, we developed presentations with several temporal alignments between sound and image (from -285ms to +300ms of audio asynchrony), at different distances from the observer (10, 15, 20, 25, 30 and 25m), and in three different conditions which differ only in the number of distance cues. The results show a relation between PSS and stimulus distance that is congruent with differences in propagation velocity between sound and light. Consequently, a model that accounts for sound velocity seems to explain the results obtained better then a model that compensates for differences in transduction time.
Audiovisual perception is still an intriguing phenomenon, especially when we think about the physical and neuronal differences underlying the perception of sound and light. Physically, there is a delay of ~3 ms/m between the emission of a sound and its arrival to the observer. On the other hand, we know that acoustic transduction is a fast process (~1ms) (Coney & Hudspeth, 1979), while phototransduction takes only ~50 ms (Lamb & Pugh, 1992). However, audio and visual stimuli that are temporally mismatched can be perceived as a coherent audiovisual stimulus (Point of Subjective Simultaneity – PSS), but a sound delay is often necessary in order to achieve a better perception of audiovisual synchrony (e.g. Alais & Carlile, 2005; Sugita & Suzuki, 2003). A PSS that requires a sound delay can be evidence for a perceptual mechanism that either accounts for physical differences or for a mechanism that compensates for the difference in transduction times between sound and light. In this study, we analyze PSS as a function of stimulus distance to understand if individuals take into account sound velocity or if they compensate for differences in transduction time when judging synchrony. Using Point Light Walkers (PLW) as the visual stimulus and sound of steps as the audio stimulus, we developed presentations with several temporal alignments between sound and image (from -285ms to +300ms of audio asynchrony), at different distances from the observer (10, 15, 20, 25, 30 and 25m), and in three different conditions which differ only in the number of distance cues. The results show a relation between PSS and stimulus distance that is congruent with differences in propagation velocity between sound and light. Consequently, a model that accounts for sound velocity seems to explain the results obtained better then a model that compensates for differences in transduction time.
Tipo de Documento
Documento de conferência
Idioma Inglês
Idioma Inglês
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