Frontal control of attentional capture in visual search

Abstract

Lavie and colleagues recently suggested that cognitive control functions that are mediated by frontal cortex provide goal-directed control of selective attention, serving to minimize interference by goal-irrelevant distractors. Here we provide new evidence for this claim from an attentional capture paradigm. An event-related fMRI experiment shows that the presence (vs. absence) of an irrelevant colour singleton distractor in a visual search task was not only associated with activity in superior parietal cortex, in line with a psychological attentional capture account, but was also associated with frontal cortex activity. Moreover, behavioural interference by the singleton was negatively correlated with frontal activity, suggesting that frontal cortex is involved in control of singleton interference. Behavioural tests confirmed that singleton interference depends on availability of cognitive control to the search task: Singleton interference was significantly increased by high working memory load. These results demonstrate the important role of frontal cognitive control of attention by working memory in minimizing distraction.

Acknowledgments

This work was supported by a Medical Research Council grant to the first author.

Notes

¹It is worth noting that, although serial spatial shifts of attention may not be required for the search process in this feature-search task (Treisman, 1988), shifts of focused attention to the target position are required for the orientation discrimination aspect of this task (in order to discriminate the orientation of the small line (0.5° of visual angle) within the target shape, among the competing orientations in the nontarget shapes). Thus, in the absence of a singleton distractor, although the target will initially pop out, focused attention will be shifted to it in order to perform the orientation discrimination task. When the singleton distractor is present, however, it will pop out more readily than the target (due to its greater salience, see Theeuwes, 1992), and thus may be wrongly selected for a spatial shift of attention. Thus, the presence of a singleton distractor should involve an extra shift of spatial attention (as attention has to be shifted once more from the distractor to the target).