A Time Course Analysis Of The Effect Of Emotion On Associative Memory:Evidence From An ERPs Study

A lot of research has investigated the effect of emotion on associative memory.Numerous research has confirmed that the emotionality of item often leads to enhanced memory for the emotional item and impaired associative memory for the non-emotional item.This phenomenon usually has been attributed to a kind of selective attention capture elicited by emotion in the information processing.However,a few new research suggested that poststimulus elaboration also played an important role in emotionally enhanced memory effect.Since it is unclear when emotion would influence inter-item associative memory in encoding phase,and what the processing mechanism of the associative memory of emotional items would be,we used ERP technique and aimed to further explore:(1)whether the effect of emotion on associative memory would be just related to attention to presenting stimulus,or would be mediated by poststimulus elaboration;(2)whether the associative memory of emotional items would just depend on recollection,or would be supported by familiarity as well.Based on such considerations above,we performed two experiments,in which we set distractor tasks in the stimulus presentation phase and post-stimulus presentation phase separately to explore the effect of emotion on inter-item associative memory.Experiment 1 firstly explored the role of stimulus presentation phase in encoding,which adopted a 2(emotion type: negative-neutral,neutral-neutral)× 2(condition:distractor,non-distractor)× 2(retrieval category: intact,recombined)mixed experimental design with condition as between-subjects variable.On the basis of the results of Experiment 1,Experiment 2 further focused on the role of poststimulus elaboration in the effect of emotion on associative memory,which adopted a 2(emotion type: negative-neutral,neutral-neutral)× 2(condition: distractor,nondistractor)× 2(retrieval category: intact,recombined)mixed experimental design with condition as between-subjects variable as well.The behavioral indexes ofdependent variable of two experiments were the accuracy of associative recognition test and the correct response time.The ERP indexes of dependent variable were the“emotion” effects and the "intact/recombined" effects.The main results and conclusions are as follows:(1)The behavioral results in Experiment 1 showed that the associative memory performance of neutral items was higher than that of emotional items in non-distractor condition,while there was no difference between them in distractor condition.The ERPs results showed at 300-500 ms,ERP amplitudes of emotional items associated with neutral items were greater than neutral items associated with neutral items in non-distractor condition,but there was no difference in ERP amplitudes between them in distractor condition.Additionally,at 300-500 ms,ERP amplitudes of intact items were greater than recombined items in non-distractor condition but there was no difference between them in distractor condition.Whereas at 500-700 ms,ERP amplitudes of intact items were both greater than recombined items in non-distractor condition and distractor condition.(2)The behavioral results in Experiment 2 showed that the associative memory performance of neutral items was higher than that of emotional items in both non-distractor condition and distractor condition.The ERPs results showed that at300-500 ms and 500-700 ms,no matter in non-distractor condition or distractor condition,ERP amplitudes of emotional items associated with neutral items were greater than neutral items associated with neutral items,and ERP amplitudes of intact items were greater than recombined items.Overall,the results mentioned above suggest that the effect of emotion on associative memory was largely based on attentive processing with a minor role played by poststimulus elaboration.The associative memory of emotional items was not only related to familiarity,but also depended on recollection.