Driven to less distraction: rTMS of the right parietal cortex reduces attentional capture in visual search

In visual search, the presence of a highly salient color singleton can slow or facilitate search for a shape target depending on whether the singleton is a distractor or coincides with the target. This is consistent with an attentional shift (attentional capture) to the salient item. This attentional capture can be driven by bottom-up or top-down processes or both. We investigated the role of the parietal cortex in attentional capture by a singleton using repetitive transcranial magnetic stimulation. Following disruption to the right posterior parietal cortex by sustained transcranial magnetic stimulation, the reaction time (RT) cost of the singleton distractor was reduced. At least part of this lessening of singleton distraction was due to the elimination of priming (top-down) effects between target and distractor singletons on consecutive trials. In Experiment 2, we presented the different conditions in separate blocks meaning any effects of the distractor can most likely be attributed to bottom-up processes. Nevertheless, there was still a decrease in RT interference from the distractor so that a reduction in priming cannot provide a full account of the results. The data are consistent with previous work positing that the right parietal cortex directs attention to salient stimuli (e.g., Constantinidis 2005, Mevorach et al. 2006), while also suggesting a role for the right parietal cortex in the integration of bottom-up salience information with memories for salient features on prior trials.