Behavioural and neural correlates of audio-visual motion in depth S Witheridge1, N Harrison2, S Wuerger3, G Meyer1 |
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1Experimental Psychology, University of Liverpool, United Kingdom |
| Low-level contextual factors such as visual expansion and disparity cues or auditory loudness changes mediate audio-visual integration, with enhanced neural and behavioural responses for looming compared to receding motion. The current research explores behavioural and electrophysiological responses to congruent and incongruent audio-visual motion signals in conditions where auditory level changes, visual expansion and disparity cues were manipulated. In a behavioural study participants were asked to discriminate audio motion direction whilst watching visual looming or receding 2D and 3D stimuli. Responses were faster and more accurate for congruent motion, with significantly larger response modulation when visual 3D (disparity) cues were presented compared to 2D presentation. Using electroencephalography in a second experiment, the same factorial design was employed but with a deviant trial task rather than motion discrimination. Significant effects of motion and disparity were observed before 300ms in posterior, temporal, central and frontal electrode positions, indicating a modulation of the visual evoked potentials by the presence of 3D cues at early processing stages. A significant main effect of congruence was observed at ca. 480ms post stimulus onset, in which incongruent trials were associated with increased negativity over frontal electrodes. |
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