| Popis: |
An observer’s inference that multimodal signals originate from a common underlying source can facilitate cross-modal binding in the temporal domain. This ‘unity assumption’ can cause asynchronous auditory and visual speech streams to seem simultaneous (Vatakis & Spence, 2007). Subsequent tests of non-speech stimuli such as the production of musical notes and impact events found no evidence for the unity assumption, suggesting it is speech-specific (Vatakis & Spence, 2008). Given that amplitude envelope (the changes in energy of a sound over time) has been shown to affect audiovisual integration, the current study investigates whether previous findings suggesting speech-specificity of the unity assumption were confounded by similarities in the amplitude envelopes of the contrasted auditory stimuli. To explore this, Experiment 1 used natural events with clearly differentiated envelopes: cello and marimba audiovisual stimuli. Participants performed an un-speeded temporal order judgments task; viewing audio-visually matched (e.g. marimba auditory with marimba video) and mismatched (e.g. cello auditory with marimba video) versions of stimuli at various stimulus onset asynchronies and indicated which modality was presented first. As predicted, participants were less sensitive to temporal order in matched conditions, demonstrating that the unity assumption can facilitate the perception of synchrony outside of speech stimuli. Results from Experiments 2 and 3 revealed that when spectral information was removed, amplitude envelope alone could not facilitate the influence of audiovisual unity. We propose that both amplitude and spectral cues affect the percept of audiovisual ‘unity’, likely working in concert to help an observer determine when to integrate across modalities.This is an author version of a published article. Please cite: Chuen, L., & Schutz, M. (2016). The unity assumption facilitates cross-modal binding of musical, non-speech stimuli: The role of spectral and amplitude envelope cues. Attention, Perception, & Psychophysics, 1-17. |
