The Audio-visual Modality Effect And Audio-visual Integration On Automatic Process In Time Perception

Time perception in several milliseconds is basis of several systems. Automatic process in time perception was well studied in auditory modality, but there were few studies in visual modality. Audio-visual modality effect and audio-visual integration of time perception were difficult and necessary to be explained. The aim of this study was to identify brain mechanism of automatic process, audio-visual modality effect and audio-visual integration in time perception using ERP within 200ms.In experiment 1, Automatic process and audio-visual modality effect of time perception were studied using a modified oddball paradigm "cross-modal delayed response". The analysis of behavior data showed that the accuracy of time perception in auditory modality was significant higher than accuracy in visual modality. The analysis of ERP data showed that the amplitude of auditory temporal MMN was significant higher than amplitude of visual temporal MMN; The main effect of attention conditions was not significant on auditory and visual temporal MMN's amplitude. The latency of visual temporal MMN was shorter in attention condition than that in inattention condition, while difference of the latency of auditory temporal MMN between attention and inattention didn't reach significance.In experiment 2, Audio-visual integration of time perception was studied in auditory, visual and audio-visual modality using the Go/Nogo paradigm. The analysis of behavior data showed that response was rapidest and the accuracy was highest in audio-visual modality. The integration related components including P70, N110, P180, P240 were obtained using audio-visual ERP-(auditory ERP+ visual ERP). The highest amplitude of four integration related components were all located in frontal lobe.According to results obtained under present experimental conditions, the following conclusion can be made:1) The automatic process dominant time perception in auditory modality, while automatic process and controlled process both affect time perception in visual modality.2) The audio-visual modality effect of time perception may be result from the memory trace is more intense in auditory modality and maintaining attention is more difficult in visual modality.3) The audio-visual integration of time perception contains four related components , P70 and N110 may be related to audio-visual integration of physical traits, P180 may be related to encoding of audio-visual integration of the duration, N240 may be related to comparing and decision of audio-visual integration of the duration.