More workload on the central executive of working memory, less attention capture by novel visual distractors: Evidence from an fMRI study

The present study examined the interaction of the central executive in working memory with visual attention. Native Chinese participants were given two versions of a number subtraction task, one of low demand and one of high demand, and were asked to ignore a simultaneously presented peripheral distractor. The distractor could be Chinese or Korean characters, familiar or novel to participants, respectively. Compared with the low-demand subtraction task, brain regions commonly associated with central executive functions, including left middle prefrontal cortex, anterior cingulate cortex, and precentral gyrus/sulcus, were significantly activated in the high-demand task. Critically, there was a significant interaction between distractor type and task demand. Novel distractors captured attention and elicited automatic visual analysis, shown by primary visual cortex activation, only when the subtraction task was of low demand but not when it was of high demand. The results provide confirmatory evidence that the extent to which higher level cognitive resources, specifically, the central executive component of working memory, are absorbed by a cognitive task has an impact upon automatic processing that occurs in response to distracting items.