Top-down feature-based selection of matching features for audio-visual synchrony discrimination.
Our previous findings suggest that audio-visual synchrony perception is based on the matching of salient temporal features selected from each sensory modality through bottom-up segregation or by top-down attention to a specific spatial position. This study examined whether top-down attention to a specific feature value is also effective in selection of cross-modal matching features. In the first experiment, the visual stimulus was a pulse train in which a flash randomly appeared with a probability of 6.25, 12.5 or 25% for every 6.25 ms. Four flash colors randomly appeared with equal probability, and one of them was selected as the target color on each trial. The paired auditory stimulus was a single-pitch pip sequence that had the same temporal structure as the target color flashes, presented in synchrony with the target flashes (synchronous stimulus) or with a 250-ms relative shift (asynchronous stimuli). The task of the participants was synchrony-asynchrony discrimination, with the target color being indicated to the participant by a probe (with-probe condition) or not (without probe). In another control condition, there was no correlation between color and auditory signals (color-shuffled). In the second experiment, the roles of visual and auditory stimuli were exchanged. The results show that the performance of synchrony-asynchrony discrimination was worst for the color/pitch-shuffled condition, but best under the with-probe condition where the observer knew beforehand which color/pitch should be matched with the signal of the other modality. This suggests that top-down, feature-based attention can aid in feature selection for audio-visual synchrony discrimination even when the bottom-up segmentation processes cannot uniquely determine salient features. The observed feature-based selection, however, is not as effective as position-based selection.
Fujisaki
Waka
W
NTT Communication Science Laboratories, NTT Corporation, Atsugi, Kanagawa 243-0198, Japan. wfujisaki@gmail.com
Nishida
Shin'ya
S
D000161:Acoustic Stimulation; D000328:Adult; D001288:Attention / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D003071:Cognition / Q000502:physiology; D004193:Discrimination Learning / Q000502:physiology; D006801:Humans; D008297:Male; D008606:Mental Processes / Q000502:physiology; D009483:Neuropsychological Tests; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D011336:Probability; D011930:Reaction Time / Q000502:physiology; D013028:Space Perception / Q000502:physiology; D013997:Time Factors; D013998:Time Perception / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*