Effects Of Sleep Deprivation On Emotion Recognition And Subliminal Emotion Priming

As an indispensable physiological phenomenon of human beings,the importance of sleep is self-evident.However,lack of sleep has become a common feature in contemporary society.People are deprived of sleep time for various reasons.More and more people sleep less than 6 hours a day.Evidence indicates that insufficient sleep not only affects human health,but also affects cognitive and emotional functions,leading to impaired social functions.This cognitive impairment caused by sleep deprivation gradually accumulates as deprivation time increases.Therefore,it is of great practical significance to study the changes in cognitive function and corresponding neural activities associated with sleep deprivation.In the laboratory,sleep deprivation(SD)is widely used as an experimental method to artificially restricting sleep,which can simulate the lack of sleep caused by disease or lifestyle.The recognition of emotional stimuli is easily affected by sleep deprivation.It is widely believed that sleep deprivation will slow down people’s emotional recognition and reduce the accuracy.Although a large amount of evidence shows that even if emotional stimuli do not enter the level of consciousness,people can perceive the corresponding emotions.However,previous studies on the effects of sleep deprivation on emotional recognition mostly focused on supraliminal(supraliminal)emotional recognition and focused on emotional faces.The extent to which sleep deprivation can affect subliminal(subliminal)emotion recognition is still an area that has not been fully studied.Therefore,the first question that this study wants to explore is whether there are differences in the effects of sleep deprivation on non-face emotion recognition at different levels of consciousness?Studies have shown that the emotional information perceived under subliminal conditions can even affect people’s emotional experience and judgment of subsequent stimuli,that is,there is a subliminal emotional priming effect.Although the subliminal priming stimuli that appear first do not enter the conscious level,the emotional information contained in them can still be processed through the subcortical pathway and affect the processing of subsequent target stimuli.Therefore,the second question that this study wants to explore is whether sleep deprivation will affect the subliminal emotional priming effect?This study intends to combine behavioral and event-related potential(ERP)techniques to explore the effects of sleep deprivation on emotion recognition and subliminal emotion priming and the underlying neural mechanisms.We recruited 23 participants(11females).Each subject was required to complete two emotion recognition tasks and subliminal emotion priming tasks,respectively,after normal sleep and 24-hour sleep deprivation.In study 1,24 positive/neutral/negative emotional pictures from Chinese Affective Picture System were selected as stimulus.By controlling the presentation time of picture stimuli,they were divided into supraliminal(167ms)and subliminal(17ms)presentation conditions.The experimental task required participants to identify three emotional pictures under two presentation conditions and give positive or negative judgments.From the results of recognition:under normal sleep conditions,subjects can effectively distinguish the emotional types of unconscious pictures,but SD will affect the ability to distinguish emotions.On the contrary,the ability to correctly distinguish emotions of supraliminal pictures is not affected by SD.From the perspective of recognition speed:when emotional pictures are consciously presented,there is no significant difference in the duration of positive and negative emotional pictures under normal sleep conditions.However,the speed of identifying negative emotional pictures significantly reduced after sleep deprivation.However,this phenomenon does not appear when subliminal presenting emotional pictures.The impact of the level of consciousness presented on emotion recognition has also been demonstrated in EEG data.The amplitude of N1 component induced under supraliminal conditions was larger,and the amplitude of early P300 component was smaller.In addition,the effect of SD on emotion recognition varies at different levels of consciousness.On the PO8 and F_Zelectrodes,conscious presentation of emotional pictures after sleep deprivation can induce greater P1 component amplitudes,but under normal sleep conditions,subliminal presentation of pictures induces a larger P1 component.Study 2 explored the impact of sleep deprivation on subliminal emotion priming by a masking paradigm.The priming stimulus(17ms)was masked by a non-emotional chessboard picture.The subjects were asked to judge(positive/negative)the emotion of target stimulus(167ms)that appeared after the masked stimulus.72 emotional images(24happy/neutral/sad)were used as subliminal priming stimuli,while the other 24 neutral emotional images were used as target stimuli.Each target stimulus is activated once by three different emotional images.From the results of recognition,half of the neutral target stimuli were consistently judged as positive and the other half as negative.This tendency is not influenced by sleep and the emotional categories of priming stimuli.From the perspective of the speed of recognition,although the main effects of sleep and priming stimulus emotional categories are not significant,there is a significant interaction between them.The recognition speed for neutral target images is faster when the priming stimulus is happy under normal sleep conditions,and faster when the priming stimulus is sad after SD.ERP results found that SD affects N1,early P300,and late P300 components.On the F_Zelectrode,the amplitude of N1 and early P300 components significantly increased after SD.On the C_Zand C3 electrodes,the amplitude of late P300 components significantly decreased after SD.Overall,Study 1 confirmed that the impact of SD on non-face emotion recognition varies with the level of subliminal.Sleep deprivation can reduce the recognition speed of suprathreshold non-face emotional pictures,but does not affect the recognition speed of emotional pictures presented under the threshold.Study 2 further examined the effect of emotional pictures presented under the threshold on the emotional judgment of subsequent neutral pictures,and found the effect of sleep deprivation.Under the condition of sad priming,the speed of judging neutral target stimuli was improved after SD.The results of this study reveal that sleep deprivation has an important impact on subliminal emotion recognition and subliminal emotion priming.But there are still limitations in explaining its mechanism.Future research should use different emotional materials,experimental paradigms and tools to conduct a more comprehensive investigation.