The Mediating Role Of Executive Function In Agerelated Working Memory Decline,and The Moderating Role Of Circadian Rhythms

This study explores the effect of executive function on the process of working memory changes with increasing age,and the effects of circadian rhythms on this process.Previous studies have shown that working memory capacity decreases with increasing age after early adulthood,and that the aging of processing speed and executive function may cause the decline of working memory capacity with age.However,many previous studies that ignored the influence of executive function classification,inhibitory function classification,and circadian rhythm have reached conflicting conclusions.Part of the reason may be that previous studies have rarely compared the effects of three types of executive functions and processing speed at the same time,and ignored the differences in task performance of different ages at different experiment times.The other reason may be the broad definition of inhibition,which doesn’t distinguish different types of inhibition.Therefore,this study explores the mediating role of executive function in the aging process of working memory on the basis of taking circadian rhythm and different kinds of executive function into consideration.Study 1 examined the mediating effects of the three kinds of execution functions and processing speed in the aging process of working memory.Since the peak time of individuals at different ages may be different,the performance of the three types of executive function and working memory capacity would be affected by the experiment time.Study 2 further explored the mediating role of the three types of inhibition in the aging process of working memory and the regulating effect of experiment time.This study assumes that the three kinds of executive functions have a mediating effect in the aging process of working memory,and that the experiment time have a moderating effect on this mediating effect.Experiment 1 required the subjects to complete executive function tasks,working memory capacity tasks,processing speed tasks,and morning-night type questionnaires(MEQ questionnaires).A mediation model was constructed.The results showed that executive function,working memory capacity,and processing speed decline during aging.Most young adults(18-30 years old)are early morning types;most elderly adults(60-89 years old)are night types.There was no significant experiment time difference in the performance of the young subjects.The inhibition,shifting and working memory capacity of the older subjects perform better in the morning,and the age difference of each task is greater in the afternoon.Inhibition,shifting and processing speed play a mediating role in the aging process of working memory,and the mediating role of inhibition is regulated by the experiment time.Based on the results of experiment 1,experiment 2 further explored the effects of different types of inhibitions on the aging of working memory capacity and the regulating effect of experimental time.The results showed that all three types of inhibitory functions decline with aging.There was no significant experimental time difference in the performance of the young subjects.The restriction,access and working memory capacity of the older subjects performed better in the morning.The age difference in the afternoon is greater than in the morning.Restriction and access play an mediating role in the aging process of working memory capacity,and the mediating role of access is regulated by the experiment time.This study concludes that restriction,access,shifting,and processing speed all play a mediating role in the aging process of working memory capacity,and that the mediating effect of access inhibition is regulated by experiment time.The research results further support the inhibition deficit theory and the two-factor framework,which helps to deepen the understanding of the aginging of working memory,and partially explains the contradictions of previous research results.Therefore,in the study of executive function and the aging of working memory capacity,it is necessary to consider the different effects of shifting,switching,and different types of inhibitory functions in the working memory aging process and the influence of experiment time.