Abstract
The perceptual load theory in selective attention literature proposes that the interference from task-irrelevant distractor is eliminated when perceptual capacity is fully consumed by task-relevant information. However, the biased competition model suggests that the contents of working memory (WM) can guide attentional selection automatically, even when this guidance is detrimental to visual search. An intriguing but unsolved question is what will happen when selective attention is influenced by both perceptual load and WM guidance. To study this issue, behavioral performances and event-related potentials (ERPs) were recorded when participants were presented with a cue to either identify or hold in memory and had to perform a visual search task subsequently, under conditions of low or high perceptual load. Behavioural data showed that high perceptual load eliminated the attentional capture by WM. The ERP results revealed an obvious WM guidance effect in P1 component with invalid trials eliciting larger P1 than neutral trials, regardless of the level of perceptual load. The interaction between perceptual load and WM guidance was significant for the posterior N1 component. The memory guidance effect on N1 was eliminated by high perceptual load. Standardized Low Resolution Electrical Tomography Analysis (sLORETA) showed that the WM guidance effect and the perceptual load effect on attention can be localized into the occipital area and parietal lobe, respectively. Merely identifying the cue produced no effect on the P1 or N1 component. These results suggest that in selective attention, the information held in WM could capture attention at the early stage of visual processing in the occipital cortex. Interestingly, this initial capture of attention by WM could be modulated by the level of perceptual load and the parietal lobe mediates target selection at the discrimination stage.
Highlights
Moment to moment, our sensory system is bombed by a tremendous amount of information
When a template being retained in working memory (WM) matched the target of visual search task, the attention can be automatically guided to the location of the target, and the search efficiency was improved [3,4,5]
The behavioural data showed that the WM guidance effect was present at low perceptual load condition, but not at high perceptual load condition
Summary
Our sensory system is bombed by a tremendous amount of information. Evidences in support of the perceptual load theory have been found in many studies with response competition paradigm [1,2,6,8], attentional capture paradigm [9,10] and inattention blindness paradigm [11] These behavioral studies suggested that interference from task-irrelevant distractors is reduced when the target is under high perceptual load. Other neuroimaging studies using similar paradigms with human participants suggested that the reappearance of a stimulus held in WM enhanced activity in the superior frontal gyrus, midtemporal, and occipital areas that are known to encode the prior occurrence of visual stimuli [28,29,30] Both perceptual load and WM representation are able to influence the visual attention selection. The present study sought to extend our previous work to investigate whether and when the earliest WM guidance could occur in the high perceptual load level of search task
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