A Study On ERP Indexes Of Police Mental Fatigue Based On Different Induced Tasks

As a kind of sub-optimal health,mental fatigue exists widely in the police.Because chronic mental fatigue is the cause of many psychosomatic diseases,there are plenty of clinical research on chronic fatigue syndrome,while the acute mental fatigue caused by job contents and quality can not be ignored.Accurate and timely assessment of acute mental fatigue,and the positive adjustment of physical and mental state can effectively avoid the occurrence of chronic fatigue in the police.When it comes to the evaluation,some researches have used ERP technology to explore the effects of mental fatigue on different cognitive functions,and found potential ERP indexes that can be used to detect mental fatigue.While there are some differences exist in these researches results,which may be due to the diverse mental fatigue induced tasks.In this study,based on the actual situation of police work and from the perspective of simulated video monitoring,written record,traffic command and other daily work of police,working memory task and persistent alert task,were designed to induce fatigue,and the suitable ERP indexes for mental fatigue detection of different police types were discussed.The purpose of the pre-experiment study was to test whether the 30-minute 2-back task and the modified Flanker task could successfully induce mental fatigue,and whether there was significant difference in the fatigue degree caused by the two kinds of tasks.A three-factor mixed experimental design of 2(group: working memory task group,persistent alert task group)×2(time: pre-test,post-test)×2(stimulus type: standard stimulus,deviation stimulus)was used,and the cost of response time and accuracy before and after the inhibitory control ability test were used as fatigue indicators.The purpose of the formal experimental study was to examine whether the standard stimulus(red circle)-P300,deviation stimulus(green circle)-P300,errorrelated negative wave ERN(NE)and positive wave PE induced by the wrong response to green circle can be used as fatigue evaluation indexes,which had inconsistent results in previous studies.The results showed that: In the pre-experiment,the response time cost and accuracy cost of the working memory task group and the persistent alert task group were significantly increased compared with the pre-test,and there was no significant difference between the two groups.In the formal experiment,the amplitude of standard stimulus-P300 and deviation stimulus-P300 in the long-term working memory task group and the persistent alert task group decreased significantly under fatigue state,while the latency period did not change significantly.The ERN amplitude of the working memory task group decreased significantly in the fatigue state,but the latency did not change significantly.In the persistent alert task group,the ERN latency period was significantly prolonged under fatigue state,but its amplitude did not change significantly.According to the results of the pre-experiment and the formal experiment,the conclusions are as follows: both the 30-minute working memory task and the persistent alert task can induce fatigue effectively,and the degree of fatigue induced is similar,but there may be some differences in the mechanism.The P300 amplitude induced by standard and deviant stimuli can be used as the evaluation index of mental fatigue induced by the two types of tasks.In ERN component induced by false reaction,amplitude was sensitive to the evaluation of mental fatigue induced by working memory task,while ERN latency was sensitive to the evaluation of mental fatigue induced by persistent alert task.Therefore,it might be more appropriate to use ERN amplitude or latency as a fatigue indicator in practical application.