The Effect Of Cognitive Control On The Memory-based Attention Guidance

Researches on selective attention suggest not only salient stimuli will capture attention;the contents of visual working memory also have a guide role on attention (i.e.,memory-based attention guidance). In spatial dimension, studies had consistently found theretention of working memory depends on sustained attention to the memorised position.Thus, stimulus processing on the memorised position will be facilitated. However, in objectdimension, the remained question is whether the contents of working memory would alwayscapture attention. According to Bias Competition Model, working memory contents are keptas attention template and stimulus matching memory item would automatically captureattention. In contrast, the Theory of Visual Attention (TVA) proposed the effect of workingmemory on attentional selection in a more flexible way. Experimental studies also found anumber of conflict results. Some researchers found the attention capture effect caused byobject working memory was obligatory. However, others indicated the contents of objectworking memory were not necessary to capture attention. Memory-matching stimulus can berejected if it was task irrelevant. In order to find an interpretation on these conflict findings,the current research investigated the role of cognitive control on the memory-based attentionguidance effect. Specifically, the current research tested (1) whether or not the contents ofobject working memory would involuntarily capture attention and (2) the role of cognitivecontrol and its time course during the guidance effect of working memory on attention.The current research employed working memory and visual search dual-task paradigm.Participants were instructed to conduct a visual search task during the retention of a memoryitem (Experiment1-6). One of the key operations throughout the whole research was:whether or not there were some search distracters matching the memory item. Suchmemory-matching items were presented in matching trials and absented in control trials. Theeffects of the memory-matching items on search performance reflect the guidance effect ofobject working memory on attention.The first research investigated whether the memory-based attention guidance effect couldbe affected by cognitive control. Cognitive control behaviours were operated by varying taskinstruction. In Experiment1, participants were directly told that “the memory item is alwaysdifferent from the search target”. The results showed visual search RTs were faster inmatching trials in comparison of control trials, suggesting memory-matching items had beenrejected and search performance had been facilitated. In contrast, search RTs were slowerwith memory-matching items in Experiment2where the above instruction was removed;suggesting object working memory contents captured attention and disrupted the searchperformance. Thus, the first research suggested:(1) the contents of object working memorycould either capture attention or be rejected by attention;(2) participants must be convincedof the irrelevance of working memory contents to search task if memory-matching itemscould be rejected. The second research further investigated the effects of cognitive control power on memory-basedattention guidance. The power of cognitive control was operated by varying the proportion ofmatching trials. The higher the proportion is, the stronger the control would be. The results ofExperiment3(behavioural experiment) showed search RTs were faster in matching trials with strongcognitive control and was slower in matching trials with weak control. Experiment4employed ERPtechnology to investigate how the effect of cognitive control varies over time. The main indexes were(1) N2pc component (about200-300ms) and (2) the positive difference waves after N2pc. The formerrelated to the attention capture effect, the later related to an inhibitory effect after attention capture.Memory-matching item only elicited the N2pc component with weak control. In contrast, both theN2pc component and the positive difference waves after N2pc caused by memory-matching itemwere found with stronger control. Furthermore, as the power of cognitive control increased, both theamplitude and the latency of N2pc component reduced, whereas the amplitude of the positivedifference waves increased. The second research suggested:(1) the contents of object workingmemory would always capture attention in the earlier process stage (about200-300ms).(2) Thecontents of object working memory could be rejected after capturing attention. The efficiency andtime course of such inhibitory effect depend on the power of cognitive control.The third research investigated the effect of cognitive load on memory-based attention guidance.The load of cognitive control was operated by conducting different secondary tasks. Participants hadto additionally conduct either a backward counting task in steps of3(high load) or an articulatorysuppression task (low load) during each trial. Experiment5(behavioural experiment) showedmemory-matching items had been rejected with low load. In contrast, they had neither capturedattention nor been rejected with high load. Experiment6used ERP technology convinced that thememory-matching item elicited neither N2pc component nor the positive difference waves afterN2pc. Moreover, the amplitude of P3component was reduced with the increase of cognitive load.The third research suggested the top-down processing during the memory-based attention guidancewas widely eliminated by the lack of cognitive resource.The current research revealed the effects of cognitive control and its time course duringmemory-based attention guidance, suggesting a powerful interpretation on previous conflict results interms of cognitive control. Firstly, the memory-based attention guidance effect was highly flexible.Memory-matching item could either capture attention or be rejection. Secondly, memory-basedattention guidance includes two phases. The contents of object working memory would alwayscapture attention during the earlier processing stage and could only be rejected in the later processingstage with sufficient cognitive resource. However, top-down processes in both the earlier and thelater phases would be greatly disrupted by the lack of cognitive resource. Broadly, the presentresearch supported the Bias Competition Model by showing that the contents of working memorywould involuntarily capture attention during earlier processing. However, such memory-basedattention capture is affected by both the power and the load of cognitive control.