Neural Mechanisms Of Accessing To Subliminal Emotional Words

Emotional words play an important role in human survival and social communication.It has been long debated to what extent high-level infor mation can be processed in the absence of awareness.Emotion word is a kind of high-level informati on.Although behavioral studies have shown that the meaning of emotional words can be accessed even without any awareness,there are still som e inconsistent r esults.Nevertheless,no consensus has been reached in previous functional magnetic resonance imaging studies,some studies revealed that emotional words that are unconsciously presented cannot activate the brain regions involved in semantic or emotional processing.Others found that the em otional word can be processed even when they are inv isible.Therefore,our goals are to explore the neural m echanism of e motional word processing in the continuous flash suppres sion and masked paradigm and to test that whether the emotional words can be processed in the unconscious condition or not.To clarify this point,E xperiment 1: In both of the visual m asking and non-m asking conditions,the participants were asked to co mplete the lexcial judgem ent task and the reaction of the cortex w as recorded by fNIRS.The resu lts showed that,in both of the visible and invisible conditions,e motional effect(negative –neutral word)and se mantic effect(intact-scrambled word)both did not sh ow any difference in the IFG,SFG,IPG.The negative result may be due to the shortcomings of the marked paradigm,and the low temporal sensitivity of BOLD s ignal which m ight not reflect the early s tage of em otional word processing in the subliminal condition.Experiment 2 used continuous flash suppression(CFS)and Electroencephalogram(EEG)techniques to distinguish the sem antic and em otional processing.In CFS,we suc cessively flashed some Mondrian-style images into one participant's eye steadily,which suppressed the images projected to the other eye.N egative,neutral,and scrambled words were presented to 16 healthy participants for 500 ms.Whenever the participants saw the stimuli—in both visible and invisible conditions—they pressed specif ic keyboard buttons.Th e results of these behavioral experiments revealed that there was no dif ference in reaction tim e to negativ e words and to neutral words in the invisi ble condition,although negative words were processed faster than neutral words in the visible condition.The ERP results showed that negative words elicited a lar ger P2 a mplitude only in the inv isible condition.The P2 component was enhanced for the neutral words compared with the scram bled words in the visible condition;however,the scrambled words elicited larger P2 amplitudes than the neutral words in the invisible condition.T ime-frequency analysis showed that the negative words induced a larger theta frequency in the fr ontal-parietal area around 250 m s-400 ms than the neutral words in the visible condition.Howeve r,the negative word induced a lar ger the parietal theta frequency than the neutral wo rds in the visible condition.There was no difference between the neutral and the scram bled words in both of the visible and invisible condition.These results draw conclusions as follows:1,emotional meaning of words can be accessed in the unconscious awareness.2,semantic processing appears to be attenuated in the absence of awareness.3,there m ight be a sub-cortex pathway in the em otional processing of words.Emotional processing of words is m ore sensitive than semantic processing in the conscious condition.