| Time expectation is a process that involves utilizing sensory or motor information containing temporal structures to predict the timing or duration of an event.Time expectation is closely related to people’s daily lives and plays a significant role in their fundamental cognitive activities.Previous studies have found that when the timing of information aligns with expectations,the brain not only enhances the perceptual processing of that information but also improves memory performance for it.Besides,time expectation can have an impact across various stages of working memory.However,the existing studies have primarily focused on the storage characteristics of working memory,neglecting its selectivity for information.As a core cognitive system,working memory has extremely limited capacity.To facilitate efficient interaction with the external environment,working memory needs to filter through a massive amount of external information and store only the most relevant information for the current task,excluding irrelevant or outdated information.Based on the author’s preliminary literature review,only one study indirectly addressed the influence of time expectation on the selectivity of working memory,and no systematic research directly targeting this issue has been found.This study aims to systematically investigate the modulation of time expectation on the selective storage of working memory and its mechanisms,in order to deepen the understanding of the relationship between expectation and working memory and further elucidate the mechanisms of selective storage of working memory from the perspective of expectation.This study was divided into three parts(including a total of eight experiments)to investigate the aforementioned question.Study 1(Experiments 1 to 4)explored whether time expectation could modulate the selective storage of working memory.In Study 1,a fixed rhythm sound was used to induce time expectation,and there were two conditions: one that aligned with time expectation and one that violated it by manipulating the timing of stimuli presentation.Study 1 focused on two types of information: the key feature that needed to be used but not memorized(Experiments 1and 2)and the irrelevant feature that was unrelated to the task(Experiments 3 and 4).The working memory-guided attention paradigm(Experiments 1 and 3)and the change detection interference paradigm(Experiments 2 and 4)were employed to test whether the representation strength of these features changed under different time expectation conditions,aiming to investigate whether time expectation could modulate the selective storage of working memory.Consistent results from the above experiments demonstrated that when time expectation was violated,the selectivity of working memory was weakened,as indicated by that both the key feature(outdated information)and the irrelevant feature(task-irrelevant information)were sroted into working memory.It indicates that time expectation can indeed modulate the selective storage of working memory.Study 2(Experiments 5 to 7)focused on investigating the universality of time expectation in modulating the selective storage of working memory.Firstly,Study 2examined whether time expectation induced by stimuli from different modalities had different modulation effects(Experiments 5 and 6).The results revealed that time expectation induced by visual stimuli(Experiment 5)and audiovisual integration stimuli(Experiment 6)could both modulate the selective storage of working memory,with no significant difference compared to the modulation by auditory stimuli(Experiment 1).It indicates that the modulation effects of time expectation do not exhibit specificity between the visual and auditory channels and do not show additive effects.Secondly,Study 2 investigated whether time expectation could be adapted.In Experiment 7,all trials were set to violate time expectation,and it was found that the modulation effect of time expectation on the selective storage of working memory was significantly weakened.Furthermore,the reduction in the modulation effect could be observed early in the experiment.These results indicate that time expectation can be adapted to and that the adaptation occurs quickly.Study 3(Experiment 8)focused on the key feature,employed the change detection interference paradigm and collected the electroencephalogram(EEG)data.Theta oscillation power was used as an indicator to investigate the mechanism of time expectation in modulating the selective storage of working memory.The results revealed that under the condition of violating time expectation,the power of theta oscillation reflecting the level of inhibition significantly decreased.This indicates that the attenuation of selective storage in working memory is achieved by reducing the level of inhibition in the brain.Based on the above results,this study draws the following main conclusions:(1)Time expectation can modulate the selective storage of working memory.When time expectation is violated,the selectivity of working memory for the key feature(outdated information)and the irrelevant feature(task-irrelevant information)is reduced.(2)When time expectation modulates the selective storage of working memory,there is no channel specificity between the visual and auditory channels.Additionally,time expectation can adapt quickly.(3)The mechanism by which time expectation modulates the selective storage of working memory involves changing the brain’s inhibition of information.Specifically,when time expectation is violated,the brain reduces the level of inhibition to weaken the selectivity of working memory for information. |
