The Prioritization Of Self-referential Stimuli In Working Memory Representation And Its Basic Neural Mechanism

Facing the complex and changing environment of social life,handling the information with social attributes is a crucial sociability,which is significant for gregarious life.In human beings' social life,the self-related information can be frequently encountered and arouse self-awareness,which is usually termed as self-referential information.There is much evidence indicating that people are biased towards information relevant to themselves.The involvement of self-referential processing can prioritise self-referential information,and further make the self-referential stimulus can be quickly captured by attention,also make the self-referential materials acquire increased memory performance(Sui & Humphreys,2015a).However,to our knowledge,few studies have examined the prioritization of self-referential stimuli in goal-oriented cognitive processing,such as working memory(WM).In the daily social life,the influence of social information on goal-oriented cognitive processing is ubiquitous,therefore,exploring how the self-referential information is processed in human cognitive system can help us to better understand human social behaviors.In the present research,conducting four studies,we first explored the prioritization of self-referential stimuli in working memory and its cognitive processing characteristics from the behavioral level,then further investigated the neural mechanism underlying the prioritization of self-referential stimuli in working memory from the neural level.In study 1,we adapted a delay-matched spatial WM paradigm and designed four behavioral experiments to test wether the self-referential WM items would show prioritization in the recognition performance.Participants were trained to hold associations between label words(self,friend and stranger)and neutral colors(the experiments in this research all contain this procedure),and then they were asked to perform the WM task in which the participants had to remember two positions and make a recognition response.Participants consistently responded fastest to WM probes at locations of selfassociated items across four experiments.In the 2nd experiment,we presented two items one by one,and found two main effects—serial order and self-reference,but there is no interaction effect between self-reference and serial order.The results of second experiment confirmed that self-referential prioritization effect neither resulted from a self-prioritization effect in capturing attention nor resulted from prior remember order of self-referential items.In the 3rd experiment,we added another dotprobe judgement during the maintenance stage and found that the dots at self-referential position would be probed faster,suggesting that the involvement of self-referential processing could induce self-bias of top-down attention.In the 4th experiment,we rendered self-referential probes a lowprobability event and still found a robust self-referential prioritization,suggesting that the biases favoring the representation of self-referential items in WM occured relatively automatically.Taken together,using four experiments,we confirmed the prioritization of self-referential stimuli in working memory and further identified that this self-prioritization resulted from the sel-bias of top-down attention.In study 2,we utilized represention precision to explore the influence of self-referential stimuli on the allocation of WM resources,the precision was calculated by the the reciprocal of the standard deviation of the error in subjects' responses(Bays,Catalao,& Husain,2009).In a visual WM task,we asked participants to remember the orientation of color bars and then participants need to rotate a black bar to match the remembered orientation of the items according to a label cue.In the 1st experiment,we found that the precision of self-referential WM items was higher than the other two referential conditions,which suggested that the self-referential items gained more WM resources than otherreferential items.In the 2nd experiment,we added a suffix to distract the representation of normal items and found that the suffix did not exert influence on the self-prioritization even though the suffix lowered the overall precision,suggesting that the superiority of self-referential items in resources competition is not due to the perceptual superiority.In the 3rd experiment,we increased the memory load and found that the self-prioritization disappeared under the high load condition(three items),which indicated that enough WM resources was a prerequisite for the the superiority of self-referential items in resources competition.After the study 2,we found that self-referential stimuli could obtain more resources in working memory,and the superiority of self-referential items in resources competition was not due to bottom-up perceptual salience,but relied on enough working memory resources.In study 3,we used functional magnetic resonance imaging(fMRI)to scan participants' brain activity when they completed the delay-matched spatial WM task.Using the whole brain activation analysis,we found that,compared with other-referential processing,the self-referential processing resulted in stronger brain activity in the self-related brain area—the ventromedial prefrontal cortex(VMPFC)and in the top-down attention area—the superior parietal lobule(SPL).Furthermore,the activity of SPL in the representation stage of all conditions was higher than that in the rest stage,which confirmed that the SPL participated in the general WM representation.After that,we used multi-voxel pattern analysis(MVPA)to analyze the neural decoding of general WM representation regions,and found that the trials with different degrees of self-reference and the position information of selfreferential items both could be decoded in the general WM representation regions.These results indicated that the self-referential processing not only induced the participation of self-related brain regions,but also resulted in stronger top-down attention processing.This top-down attention bias could further enable the general WM representation regions to store the abstract information of selfreference and the information about differential representation of visual position induced by selfreference.In study 4,we used psychophysiological interaction(PPI)analysis to test the change of functional connectivity caused by self-referential processing.We found that,compared with the other-reference,representing the self-referential WM item induced increased functional coupling between VMPFC and top-down attention areas and the mean strength of these couplings was positively associated with the behavioral self-prioritization effect.In addition,using the resting state fMRI data,we calculated the functional connectivity between the default mode network and the dorsal frontoparietal network,then we also found a positive correlation between the coupling strength of two networks and the behavioral self-prioritization effect.These results suggested that the synchronous functional coupling between default mode network and cognitive processing network was the neural basis of the self-prioritization effect in WM.In summary,the most important heuristic contribution of present research is the discovery for the first time that self-referential processing can induce sel-bias in top-down attention processing.By combining two different research fields,we investigated the cognitive processing in a more actual social situation,unlocked the self-prioritization effect in goal-oriented cognitive processing.This kind of information with strong social attribute can seep into the goal-oriented cognitive processing,meaning that our rational cognitive system can also be affected by the emotional information.On the other hand,we have identified the neural mechanism of this effect from the level of brain science,and found that the self-referential processing not only resulted in additional involvement of top-down attention processing,but also caused the storage of abstract self-referential information in the general WM representation regions.The pattern of brain activity highlights the unique interrelationship between the default mode network and the cognitive processing network,and the synchronical functional coupling between the two networks is the neural basis for the self-prioritization effect in WM.The current paradigm allows us to study the complex and changing social cognition in the controllable laboratorial situation,and makes the research results from laboratory more propagable.For the self-reference and working memory,the present research can provide a new way to study them and a new perspective to understand them.