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Abstract:
Most research on attention so far has focussed on orienting in the extrapersonal world. But recently it was demonstrated that it is also possible to orient spatial attention to locations held as mental representations in working memory. This is an important issue, since the allocation of our attention is not only guided by external stimuli, but also by their internal representation and the expectations we build upon them. The present experiment investigated whether spatial orienting can modulate the search and retrieval of information from working memory. We combined behavioural and event-related fMRI measures to investigate the effect of spatial orienting to internal representations of arrays with different sizes and to identify the neural systems involved. Participants viewed an array of coloured crosses. Seconds after its disappearance, they were cued to locations in the array with valid or neutral cues. Subsequently, they decided whether a probe stimulus was presented in the array. The behavioural results indicated that orienting spatial attention within working memory attenuates the typical effect of decreasing performance with increasing memory load. Thus spatial orienting can highlight information or facilitate search within working memory, leading to advantages in retrieval. In general, this process was supported by a network of frontal and parietal areas, similar to the network involved in attentional orienting in the external world. FMRI analyses teased apart brain areas sensitive to increases in working-memory load versus spatial orienting functions. Increasing load was accompanied by increased activity in premotor and prefrontal cortices, whereas orienting of attention activated regions in the right superior parietal lobule, medial frontal gyrus and frontal operculum.
