The Processing Prioritization Of Stressful Information In Working Memory

Stress refers to the nonspecific reactions when individuals face real or potential threat stimuli.People often experience stress in daily life.On the one hand,people need to complete cognitive tasks under stress.On the other hand,people may face and process stressful information again after experiencing stress.Stressful information refers to the things that are closely related to the stressors in the stressful situation.In the stressful situation,the thing directly related to the stressors is described as central object(CO),and the thing not directly related to the stressors is described as peripheral object(PO).Importantly,the CO is the direct source of stressful information.In the domain of the interaction of stress and cognition,the interaction between acute stress and working memory is one of the important research issues,and has received widespread attention in recent years.Working memory is a limited-capacity system that serves to temporally maintain information during cognitive tasks and is essential for many ongoing cognitive tasks.Previous studies on the interaction between acute stress and working memory mainly focused on completing working memory tasks in the context of acute stress.The tasks completed by subjects had nothing to do with the stress itself,but little was known about how to encode,store and manipulate stressful information in working memory.Meanwhile,the study about the relationship between stressful information and long-term memory found that stressful information has processing prioritization in long-term memory,and people have better recall performance for stressful information.However,less is known about whether the processing prioritization of stressful information in long-term memory exists in working memory.Therefore,we conducted four studies including a total of 12 experiments to explore the processing prioritization of stressful information in working memory.All experiments included two stages.In the first stage,the subjects’ acute stress was induced by Maastricht acute stress test(MAST).During the task,different colors were connected with the things through operation to obtain CO and PO in the stressful situation.The thing that did not appear in the stressful situation was described as neutral episode(NE),which was represented by other colors.In the second stage,CO,PO and NE were used as experimental materials in working memory tasks.Except for Experiment 2,subjects in all other experiments need to rest in a quiet room for 1 hour after the MAST task,and then completed the working memory tasks after the cortisol concentrations had returned to the baseline level.All experiments included a stressful group and a control group.The only difference between the two groups was that the subjects in control group were not induced acute stress.In order to avoiding the influence of cortisol rhythm on the experimental results,all experiments were completed between 1:00 p.m.and 6:00 p.m.The studies determined whether the stress induction was successful by analyzing and comparing the measured scores of a series of emotional questionnaires and the cortisol concentrations of subjects.The results showed that the stress operations in all experiments were successful.The purpose of Study 1 was to investigate whether stressful information had processing prioritization in working memory and the specificity of the processing prioritization.The Study 1included three experiments.Experiment 1 used the delayed matching judgment task to explore whether the stressful information had processing prioritization in working memory after the cortisol concentrations had returned to the baseline level.The results showed that the reaction time of CO was significantly faster than that of PO or NE,which proved that stressful information had recognition prioritization in working memory.In Experiment 2,the subjects were required to start the working memory task immediately after the MAST task.The results showed that stressful information also had processing prioritization in working memory before the cortisol concentrations had returned to the baseline level.In Experiment 3,stressful information and general threat stimuli were compared in working memory processing.The results showed that stressful information had prioritization compared with general threat stimuli in working memory processing.The results of Study 1 preliminary proved that stressful information had stable processing prioritization in working memory,and the prioritization had certain specificity.The Study 2 examined the effects of stressful information on the attention resources distribution,and we chose the coding stage of working memory as an investigation window.The Study 2 included three experiments.Experiment 4 explored whether the processing prioritization of stressful information with insufficient coding time(50ms)was different from that with sufficient coding time(500ms).The results showed that stressful information had processing prioritization in working memory both under the two coding time conditions.Based on the Experiment 4,Experiment 5 set two different working memory loads including load 2 and load 3to explore the effects of the loads on the processing prioritization.The results showed that stressful information still had processing prioritization in working memory under the two load conditions.In Experiment 6,we used the oriented recall task to investigate whether the stressful information had the prioritization of representations precision in working memory.The results showed that the processing prioritization of stressful information could be reflected in the representations precision,and it was not regulated by working memory loads in essence.The results of Study 2 showed that the processing prioritization of stressful information in working memory was not regulated by coding time and working memory loads,and individuals could flexibly allocate attention resources among targets.In the case of insufficient attention resources or attention resources competition,stressful information still had the priority to be processed.The Study 3 was to explore whether stressful information had more stable memory representation in working memory,and we chose the retention stage of working memory as an investigation window.There were four experiments in Study 3.Experiment 7 demonstrated that the stressful information also had processing prioritization in the retention stage of working memory by presenting memory items sequentially.Experiment 8 set the stressful information as target stimuli and interference stimuli respectively to investigate the influence of interference on the processing prioritization of stressful information and the interference effects of stressful information on target stimuli.The results showed that the processing prioritization of stressful information still existed when we added interference stimuli.At the same time,the interference effects of the target processing got greater when the stressful information was used as interference stimuli irrelevant to the task.On the one hand,the results showed that the processing prioritization of stressful information was not affected by interference stimuli;on the other hand,in considering that the processing prioritization of stressful information in the Study 2 was not sensitive to working memory loads,the current results indicated that the processing of stressful information in working memory had automatic characteristics.Experiment 9 investigated the effects of recession(setting three kinds of retention time including 500 ms,3000ms and 6000ms)on the processing prioritization of stressful information.The results showed that the processing prioritization of stressful information still existed under three retention time conditions,which indicated that the processing prioritization of stressful information was not affected by recession.Experiment 10 was inserted a point detection task in the retention stage of working memory.The results showed that the reaction speed was faster when the detection point appeared in the position of stressful information,which indicated that stressful information could induce internal attentional bias and guide internal attention from the top down.The results of Study 3 showed that stressful information had more stable memory representation in the retention stage of working memory.The stable representation could not only protect the processing prioritization of stressful information from interference and recession,but also guide internal attention from the top down.Moreover,the processing of stressful information had certain automatic characteristics in working memory.The Study 4 mainly explored whether the processing prioritization of stressful information in working memory could be regulated by attention,and this study contained two experiments.In Experiment 11,subjects’ attention was guided by top-down pre-cues,and subjects were required to actively pay attention to or suppress the targets to study the attention regulation of the processing prioritization of stressful information in the coding stage of working memory.Experiment 12 used retro-cues to guide subjects to pay attention to or suppress memory items to study the attention regulation of the processing prioritization of stressful information in the retention stage of working memory.The results of the two experiments showed that subjects could pay more attention to stressful information than other stimuli when they were asked to actively pay attention to target stimuli,while it was more difficult for subjects to inhibit stressful information when they were asked to actively suppress target stimuli processing.To sum up,this study explored the processing prioritization of stressful information in working memory,and drew the following conclusions.First of all,stressful information has stable processing prioritization in working memory,and the processing prioritization has certain specificity.Secondly,the processing prioritization of stressful information in working memory is not regulated by coding time and working memory loads.In the case of insufficient attention resources or attention resources competition,individuals can flexibly distribute attention resources among stimulus items,so that stressful information can obtained processing prioritization.Thirdly,stressful information has more stable memory representation in the retention stage of working memory.The stable representation of stressful information can not only protect the processing prioritization of stressful information from interference and recession,but also guide internal attention from the top down.Fourthly,stressful information has automatic characteristics in working memory processing.Finally,stressful information can be actively attended through attention regulation,but it is relatively difficult to be suppressed.The research results can not only expand the fields of interaction between stress and working memory,but also play a vital role in understanding the cognitive processing characteristics of the groups such as acute stress disorder(ASD)and posttraumatic stress disorder(PTSD),as well as recovering their mental health.