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The Effect Of Working Memory Load On Cognitive Flexibility From Behavioral And Electrophysiological Evidence

Posted on:2021-03-03Degree:MasterType:Thesis
Country:ChinaCandidate:G Q DingFull Text:PDF
GTID:2415330620969329Subject:Basic Psychology
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Executive function refers to a kind of advanced cognitive function that controls and coordinates various cognitive processes when completing complex cognitive tasks,so that the cognitive system can achieve specific goals in an optimized and flexible way.In recent years,it has been the focus of research in psychology and cognitive neuroscience.As two components of executive function,the relationship between working memory and cognitive flexibility remains controversial.Some researchers have claimed that cognitive flexibility(indexed as switch cost)is not affected by WM load.However,other researchers have found that working memory load has an obvious influence on switch cost.In order to explore whether working memory load affects cognitive flexibility,we the event-related potential(ERP)method to investigate it from different perspectives through two experiments.In the first experiment,firstly,participants had to remember 2(low load)or 3(high load)two-digit numbers as reference numbers cued by different shapes;then,a series of numbers(10–99)were presented one by one for comparison,and participants were instructed to judge whether a comparison number was larger or smaller than the corresponding reference number maintained in WM.In the behavioral results,switch trials had greater reaction time and lower accuracy than repeat trials;moreover,the switch cost was greater in the high-load condition than in the low-load condition.On the ERP results,switching effect was significant in N1,P2,N2 and P3 time windows;load effect was significant in P2 and P3 time windows;what is more,memory load and task switching had a significant interaction in the N2 and P3 time windows.Further analysis revealed that the difference(switching minus repeating)in the N2 and P3 amplitudes was greater in the high-load condition than the low-load condition.For the first experiment,the task rule is comparing the magnitude of the current digit with the reference number embedded in the identical shape in the previous working memory regardless of the memory load task.Therefore,the task rules are not switched in the experiment.In the second experiment,we adapted a numerical alternate comparison task into different loading rule switching tasks(magnitude,parity,and distance).Participants were required to judge whether a number was lower or higher than 5,judge whether a number was odd or even and judge whether the distance between a number and 5 is greater than 2.5.In the behavioral results,switching trials had greater reaction time and lower accuracy than repeat trials;moreover,the switch cost was greater in the high-load condition than in the low-load condition.On the ERP results,switching effect was significant in P2,N2,P3 and LPC time windows;load effect was significant in P2 and LPC time windows;what is more,memory load and task switching had a significant interaction in the N2,P3 and LPC time windows.Further analysis revealed that the difference(switching minus repeating)in the P3 and LPC amplitudes was greater in the high-load condition than the low-load condition.Both the behavioral and neurophysiological results of the two experiments in this study showed that the greater the memory load,the more difficult the task switching,and the higher the switching cost.Based on two neurophysiological results,we found that the effects of memory load on cognitive flexibility were mainly reflected in conflict detection,task reconstruction and rule learning and application.
Keywords/Search Tags:Cognitive flexibility, Working memory, Working memory load, Switch cost
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