Causal Perception Promotes Audiovisual Temporal Integration

Cross-modal integration,also known as multisensory integration,refers to the process by which individuals effectively integrate information in different sensory channels into a unified,coherent and complete multisensory event.This processing process can integrate the information input from different sensory channels into the central nervous system to form a holistic perception to help individuals better perceive and adapt to the environment.Among them,audiovisual integration has always been a key research field of cross-modal integration,and previous studies have found that temporally adjacent audiovisual information are more easily integrated.Therefore,this study focuses on the temporal relationship of audiovisual stimulus and explores the audiovisual temporal integration in cross-modal integration.On the other hand,individual tends to perceive objects with causality as a whole event,thus affecting the judgment of individuals in the form of causal perception,such as the perception of time distance between objects.However,does the causality(or causal perception)of the object in the perception process affect the audiovisual temporal integration? Previous studies have not discussed this in depth.For this reason,two experiments were used in this study.Experiment 1 combined the classic object collision paradigm of causal perception with the classic simultaneous judgment task in audiovisual temporal integration,and used the temporal binding window of audiovisual temporal integration as a behavior indicator to explore whether causal perception affects the audiovisual temporal integration.The results found that: under the condition of causality,the temporal binding window of subjects are significantly narrower than that of the non-causality relationship,that is,the subject is more sensitive to the time interval of audiovisual stimulation,which promotes the integration of audiovisual temporal integration.This result proves that causal perception does promote the audiovisual temporal integration.Experiment 2 was based on EEG experiments.Based on experiment 1,the internal mechanism was explored.Whereas previous studies have found that the alpha wave of neural oscillations is closely related to the temporal information of perceptual processes and cross-channel sensory integration,it represents the time unit of information processing,and has an important relationship with individual causal judgments on objects.Therefore,experiment 2 used the same paradigm as experiment 1,and took the instantaneous frequency of nerve oscillations as an indicator.Focus on testing whether the alpha instantaneous frequency can be used as a neural indicator,reflecting the neural processing of causal perception affecting the integration of audiovisual time.The results show that compared to the non-causal condition,the instantaneous alpha frequency is significantly increased under the condition of causality.Furthermore,we compared the theta,beta instantaneous frequency,event-related spectral perturbation,and found that there was no significant difference in these indicators between two conditions.Therefore,the effect of causal perception on the audiovisual temporal integration is only manifested in the alpha band of neural oscillations.In summary,we explored the role of causal perception in promoting the audiovisual temporal integration from the perspectives of behavior and neural activity.The research results are as follows:(1)Causal perception does affect the integration of the audiovisual temporal integration;specifically,when there is a causal relationship between objects,the temporal binding window of audiovisual integration is significantly narrower than the non-causal condition.(2)The effect of causal perception on the audiovisual temporal integration occurs at the level of neural oscillation coding,which is specifically manifested by the causal relationship significantly increasing the alpha instantaneous frequency,thereby increasing the individual's sensitivity to the time interval and promoting the integration of audiovisual time.