| Multisensory integration refers to the process in which the brain effectively integrates information from different sensory channels(such as vision,hearing,etc.)simultaneously.In daily life,many of the objects and events we encounter are different information mixed from the auditory and visual or other sensory channels.Although multi-sensory experiences are universal in life,the relationship between multi-sensory integration and consciousness is still not very clear.So far,most studies on unconscious and multisensory integration have at least one channel stimulus that is above the threshold level and cannot be used as the proof of integration under unconscious conditions.On the completely unconscious dual-channel integration,only Faivre et al.used a unique priming paradigm to study the numbers in audio-visual threshold and found that unconscious audio-visual integration must occur on the premise of conscious training.Barutchu and Spence used simple semantic consistency judgment tasks to study patients with posterior cortical damage(Posterior Cortical Atrophy,characterized by visual impairment in the cortex),and found that multi-sensory signal processing was enhanced even without prior learning or awareness training.Therefore,this study aims to examine whether conscious training is necessary for audiovisual integration under completely unconscious conditions,the duration of subliminal audio-visual integration in the priming effect,and the processing mechanism of complete unconscious audio-visual integration.This paper includes three studies and five experiments.Study 1 adopted the congruency priming paradigm to analyze the priming effect of subliminal audiovisual digits on target stimuli through the experimental data of two groups of subjects(conscious training group and unconscious training group),in order to examine whether subliminal audiovisual digits needed conscious training to achieve multi-sensory integration.In Experiment 1,visual number and digital pronunciation(auditory)were used as priming stimulus pair(audiovisual semantic relationship was the same,different)and visual color block and color pronunciation(auditory)were used as target stimulus pair(audiovisual semantic relationship was the same,different)to constitute priming-target relationship(congruency,uncongruency).The tasks of two groups of subjects(conscious training group and unconscious training group)were the key-press response on whether the audiovisual semantic relationship of the target stimulus was the same or not.The experimental results showed that only under the condition of conscious training,a uniform priming effect could be produced and the subliminal audiovisual digits were integrated.Experiment 2 adjusted the priming stimulus of unconscious training group in Experiment 1 and the priming stimulus used in unconscious training stage and subliminal experiment stage was even to examine whether there was a consistent priming effect under the same priming stimulus in two stages.It was found that,although the two stages of priming stimulus were the same,the unanimous priming effect could not be produced under the condition of unconscious training.On the contrary,the effect on the target stimulus response was more due to the target semantic relationship(the same;different)factors.Study 1 used consistent priming paradigm and subliminal audiovisual numbers as priming stimuli.Study 2 explored subliminal audiovisual numbers as priming stimuli on the basis of Study 1.If there is priming effect,how much was the maximum stimulus interval(SOA)between priming stimuli and target stimuli allowed?In experiment,3(stimulus interval:300ms,500ms,1000ms)X 2(priming-target relationship:congruency,uncongruency)X 2(audiovisual semantic relationship was the same,different)were designed to probe the maximum stimulus interval produced by the consistent priming effect in audiovisual dual channels.Study 3 collected EEG data and analyzed the phase synchronization of subliminal digital audio-visual EEG signals by Hilbert transformation.The processing mechanism of subliminal audio-visual digital signals was investigated by phase synchronization analysis of audio-visual EEG signals.The study focused on detecting the occurrence of synchronization between the visual brain region(occipital lobe)and the auditory brain region(temporal lobe).Experiments 4 and 5 all adopt the congruencey priming paradigm,and the phase sychronization of the audio-visual EEG signals and the sub-threshold audio-visual start-stimulation(experimental conditions)EEG signals are synchronized with the audio-visual start-up stimulation screen as a blank screen(baseline condition).Comparing the differences,if the synchronization index between the occipital lobe of the latter is higher than the former,it indicates that the audio-visual EEG signal in the unconscious state has a stable synchronization relationship and is integrated.The baseline condition is that when the stimulus screen is empty,there are audiovisual masking stimuli around it.In Experiment 4,subjects were asked to judge the audiovisual semantic relationships of the priming stimulus in the subliminal experiment stage and to perform the forced task;in Experiment 5,subjects were not required to judge the audiovisual semantic relations of the priming stimulus,that is,they did not need to perform the forced task.The conclusions are as:1)Audiovisual digits in unconscious state can produce multi-sensory integration.However,subliminal audiovisual integration needs conscious training before integration occurs,and the integration process has semantic processing;2)As a subthreshold priming stimulus,the duration of audiovisual integration stimulus is relatively short.SOA between priming stimulus and target stimulus has priming effect only within 300 ms;3)In the unconscious state,the occurrence of multi-sensory integration requires not only conscious training,but also conscious attention driven by top-down goals. 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