Research On The Processing Mechanism Of Dual Representation States In Visual Working Memory

Visual working memory enables individuals to keep a portion of information in their heads so that they can continue to store and manipulate information as required by the task after the visual input disappears.In daily life,we often need to face complex dynamic cognitive processing,which requires individuals to be able to adjust the relevance of working memory content in real time according to the current task requirements.Related memory items are placed in the center of current consciousness,while other information linking to future tasks can be maintained in the mind for a short time.In order to adapt to the dynamic nature of working memory storage,some researchers build a state model of working memory,which realizes the flexible storage of information by establishing a connection between attention and working memory.In this model,the short-term maintenance of information is understood as the attention selection of information in long-term memory or perceptual situations.An important point of the state model is that information in working memory can be maintained in at least two different representational states: those items serving the current task are selected to enter the focus of attention and thus remain in a highly accessible online state;Other items that are not used by the current task but may be invoked in future tasks are unloaded to an offline state outside the focus of attention for temporary maintenance.In recent years,researchers have focused on how different representational states of visual working memory are effectively stored,and what neural mechanisms they might involve.Around these two aspects,the existing research evidence can confirm that in the field of visual working memory,online state storage is mainly carried out by means of sensory requisition,and an active-resting synaptic model is developed to explain the offline state storage mechanism,indicating that the two representational states have separable neural substrates.Although the emphasis on the state model in recent years has promoted some empirical studies on the model,it still has a lot to be improved.First,the researchers have not yet considered how the model fits into existing theories of visual working memory capacity.The latter holds that visual working memory is limited by its limited storage capacity,which is at odds with the idea that the offline state can get rid of its capacity limit by using a long-term memory mechanism.Second,the state-based working memory framework suggests that there may be a connection between visual working memory and visual attention.Finally,both theoretical and empirical studies support the critical role of internal attention in participating in the regulation of memory in different representational states.However,the operation of the attention mechanism itself is complex and multi-component,which means that it is necessary to further explore the specific regulation mode of internal attention from the attention processing itself.Therefore,the operation mechanism of different representational states of visual working memory needs to be further studied and discussed.This thesis mainly focuses on the topic of visual working memory processing based on different representational states,and discusses four important questions through 9experiments in 4 studies :(1)whether the online and offline states of visual working memory have their own independent storage resources;If so,(2)what are some key characteristics of offline state storage? And,(3)how storage processing is carried out in different representational states,and whether they are different in requisition of visual attention resources;Finally,(4)explore the participation mechanism of internal attention in regulating working memory items in different representational states,that is,whether the selection of internal attention and inhibition function participate in respectively loading related memory items into the online state and unloading temporarily unrelated items into the offline state.Study 1 used the retro-cue paradigm to regulate the online and offline states of working memory items,and examined whether different representation states had independent storage resources.The basic logic of this study is to regulate the storage load of one representation state and observe its impact on the storage load of another representation state.Based on this logic,Experiment 1 increased the storage load of the online state by manipulating post clues,and found that only items located in the online state were impaired in memory performance,while items located in the offline state were not affected.In Experiment 2,by changing the storage load in the offline state,it was also found that increasing the storage load in the offline state only reduced the memory performance of items located in the offline state,and items located in the online state were also not affected.Along both directions,Experiment 3simultaneously regulated the storage load in both online and offline states through the subject’s internal design,and found that items stored only in the same representational state exhibited impaired memory performance,while the other representational state item was not affected.This means that the online and offline states of visual working memory have independent storage resources,while the offline storage also has limited capacity.Study 2 was designed to examine multiple key characteristics of offline storage of visual working memory.Among them,Experiment 4 compares the conditions under which unrelated memory items can be discarded with the conditions under which unrelated memory items need to be unloaded to the offline state to detect the impact of both conditions on online and offline storage processing.It was found that discarding and unloading memory items to the offline state did not affect online storage,indicating that online and offline storage processing can operate relatively independently;Experiment 5 examined whether individuals were able to strategically discard memory items or unload them into the offline state for continued maintenance.It was found that when it was unlikely that uncluttered items would be called again,participants were able to effectively discard them,indicating that unloading memory items into the offline state for continued maintenance was an active and strategic processing process;Finally,Experiment 6 examined the time process of unloading non clue items into offline storage and compared it with the condition of allowing the abandonment of non clue items.It was found that unloading non clue items into offline storage is a slower process than discarding them,indicating that unloading memory items into offline storage takes some time to complete.In study 3,the dual-task model was used to deprive working memory of visual attention resources during the delay,and behavioral measurements and neuroelectrophysiological indicators were used to investigate whether the storage processing of different representational states of visual working memory is different in the aspect of requisition of visual attention.Experiment 7 examines the visual attention through change detection paradigm in the role of visual working memory storage real-time processing,deprived of their visual working memory maintaining phase point to memory characterization of visual attention can decrease during the period of delay reflect storage and processing of the contralateral delayed activity,and the degree of visual attention resources deprived and reflect the storage and processing of ERP,and performance indicators at the individual level is closely related to.Then,experiment 8 regulated memory items to be in different representational states by double-postposition cue paradigm,and found that deprivation of visual attention only affected the storage of online visual working memory,but not the offline state.These results show that visual attention is only necessary for online state storage of visual working memory,further confirming the separation between online state and offline state of visual working memory.Study 4 investigated the alpha oscillating mechanism of switching between different representational states of working memory by combining the dual post-cue paradigm with neuroelectrophysiological techniques(experiment 9).The results show that the project only in the online state induces contralateral delayed activity higher than the baseline,suggesting that the project in the offline state may obtain storage by the mode of activity rest.Postposition cues were used to modulate the working memory items into the online state and the offline state.The consistency of the two shows that the selection of the related memory items and the synchronization of the suppressed processing of the off-line items are carried out.Crucially,this difference in the alpha lateralization of the occipital lobe was reversed when the storage state of these memory items was switched,suggesting that alpha lateralization of the occipital lobe could track representational state changes in the memory items.In time history,the alpha skew of related items decreased first,followed by the alpha skew of unrelated items increased,reflecting the attention processing of a sequence.Thus,selective attention enhancement and inhibition are both involved in the regulation of working memory items in different representational states,and the different processes of internal attention selection are carried out in a dynamic and flexible manner over time.Based on the above results,this thesis extends the state model of working memory from the following four aspects.First,previous studies have revealed that the online and offline states of working memory have separate brain mechanisms,while the current study further shows that they also enjoy their own independence in memory processing.Therefore,different representational states of working memory can be run in parallel based on independent neural substrates and storage resources.Secondly,this thesis reveals some key characteristics of offline state storage for the first time,specifically,offline state is also a system with limited storage capacity,unloading memory items to offline state is not an automatic process,and this process requires more time to complete compared with discarding unclue items.Thirdly,visual attention is necessary for the maintenance and processing of visual working memory.However,visual attention is needed for the maintenance and processing of working memory in the online state only.This means that the offline state mechanism of visual working memory can be used as a background storage mechanism when attention resources are occupied by other cognitive processing.Finally,the present study further reveals the possible mechanism by which internal attention is involved in regulating working memory projects in different representational states.Cortical activation and inhibition mechanisms mediated by alpha oscillations in the occipital lobe may reflect the attentional operation of loading memory items into the online state and unloading them into the offline state.The separability of the two in time indicates that the selection and suppression of internal attention can operate independently.