The Effects And Mechanisms Of Emotional Motivational Dimension On The Maintenance And Manipulation Of Working Memory

Background:The effect of emotion on cognition is an important aspect in the field of emotion and cognition.Previous literature presented that emotion could affect working memory and might further impact cognitive function through working memory.Nevertheless,the impact of emotion on working memory remains controversial,which might be explained by the fact that the association between emotion and working memory might be affected by the type of emotion,the type of task materials and task requirement of working memory.At the beginning,the researchers mainly focused on the effects of valence on working memory.Later,Gable and Harmon-Jones proposed a motivational dimension model of affect.Researchers started to explore the effect of motivational dimension on working memory.The model proposed apart from valence and arousal,another important aspect of emotion was the motivational dimension and the motivational intensity was the key factor to determine the impact of emotion on cognitive processing.The model presented that affect low in motivational intensity enhanced cognitive processes,while affect high in motivational intensity resulted in a general deterioration in cognitive performance.According to different task materials,working memory could be divided into verbal and spatial working memory,which processes verbal and spatial information,respectively.Additionally,working memory could be categorized into maintenance and manipulation based on different task requirements.Thus,there are two reasons that might account for the inconsistent findings in previous literature.On the one hand,most studies only considered the effects of valence and arousal on working memory without taking the motivational dimension into consideration.On the other hand,the controversial findings might be attributed to the fact that previous literature did not clearly explain upon which types(verbal and spatial)and aspects(maintenance and manipulation)of working memory the studies were focused.Methods and Results:The present study investigated the effects of high versus low avoidance-motivated negative emotion and approach-motivated positive emotion on the maintenance and manipulation of verbal and spatial working memory and explored the underlying mechanisms using electroencephalographic(EEG)technology.Firstly,according to the motivational dimensional model of affect,five types of pictures were selected from the Chinese Affective Picture Systems(CAPS)and the Internet resource:fear pictures(high avoidance-motivated negative affect),sad pictures(low avoidancemotivated negative affect),object pictures(neutral affect),beautiful landscape pictures(low approach-motivated positive affect),and delicious food pictures(high approach-motivated positive affect).A total of 49 subjects were asked to view each affective picture and rate valence(1=very unpleasing,9=very pleasing),arousal(1=very calm,9=very exciting),and motivational intensity(1=extremely want to avoid,9=extremely want to approach).The results presented no significant difference in valence and arousal and significant differences in motivational intensity between the emotions with the same motivational direction.Significant differences were found in all three dimensions between emotions with high/low motivational intensity and neutral emotion.These suggested the requirement to manipulate motivational dimension under the control of other dimensions was satisfied.The affective pictures were used to induce different emotions.Within-subject experimental design was employed in six behavioral experiments and four EEG studies to explore the effect of motivational intensity on working memory performance and its underlying EEG mechanisms.Behavioral experiments 1 and 2 investigated the effect of motivational intensity on the maintenance and manipulation of verbal working memory performance through Chinese version letter-number sequencing task.Behavioral experiments 3 and 4 modified the Chinese version letter-number sequencing task to make the paradigm more consistent with the characteristics of the maintenance and manipulation of verbal working memory to explore the influence of motivational intensity on verbal working memory performance.Behavioral experiments 5 and 6 employed the delayed match-to-sample task combined with the mental rotation task as the manipulation of spatial working memory to explore the impact of emotional motivational intensity on spatial working memory performance.In order to examine the EEG mechanisms behind the effect of motivational dimension on the manipulation of working memory,EEG experiments 1 to 4 adopted event-related potential(ERP)and time-frequency analysis to analyze the amplitude of P3 during the delaying phase,the amplitude of late positive potential(LPP)during the matching phase and theta and alpha band power during the delaying phase of the manipulation of working memory.Based on the above research,the following findings were summarized.(1)The behavioral results showed that motivational intensity only affected the manipulation of verbal and spatial working memory and did not influence the maintenance of working memory.(2)The behavioral results presented motivational intensity moderated the effect of valence on the manipulation of working memory.Compared with neutral emotion and low avoidance-motivated negative emotion,high avoidance-motivated negative emotion impaired the manipulation of verbal and spatial working memory performance.There was no significant difference in the performance between neutral condition and low avoidancemotivated negative condition;In comparison to neutral emotion and high approachmotivated positive emotion,low approach-motivated positive emotion facilitated the manipulation of working memory.No significant difference between neutral condition and high approach-motivated positive emotion was observed.Specifically,the reaction times in the fear condition were significantly longer than those in the sadness condition and neutral condition.No significant difference in performance between sadness condition and neutral condition was reported.And the reaction times were smaller in the landscape condition than those in the food condition and neutral condition.There was no significant difference in working memory between food condition and neutral condition.(3)The results of time domain analysis presented that in the manipulation of verbal working memory task,the amplitude of LPP in the matching phase was significantly lower under the high avoidance-motivated negative condition than that under neutral condition and low avoidance-motivated negative condition.The amplitude of P3 in the delaying phase and the amplitude of LPP in the matching phase were significantly higher under the low approach-motivated positive condition than those under the neutral condition and high approach-motivated positive condition.(4)The results of time domain analysis presented that in the manipulation of spatial working memory task,the amplitude of P3 in the delaying stage and the amplitude of LPP in the matching stage were significantly lower under the high avoidance-motivated negative condition than those under neutral condition and low avoidance-motivated negative condition.The amplitude of P3 in the delaying phase was significantly higher under low approach-motivated positive condition than that under neutral condition and high approachmotivated positive condition.(5)In the delaying phase of the manipulation of both verbal and spatial working memory tasks,the results of time-frequency analysis showed theta and alpha band power were lower under the high avoidance-motivated negative condition and were higher under the low approach-motivated positive condition.Conclusion:In summary,motivational intensity influences working memory performance through affecting the manipulation of working memory,and does not influence the maintenance of working memory.High avoidance-motivated negative emotion impairs the manipulation of verbal and spatial working memory,while low approach-motivated positive emotion improves the manipulation of working memory.The current study confirms the effects of valence and motivational intensity on working memory performance and provides empirical evidence for the application of motivational dimensional model of affect in the field of working memory.