Abstract
Salient stimuli are widely held to compete for spatial attention, either resulting in direct attentional selection or generating an ‘attend-to-me’ signal that must be actively suppressed (e.g. Sawaki & Luck, 2010). The N2pc and PD (Hickey, Lollo & McDonald, 2008) event-related components are thought to reflect these processes, respectively. However, previous research examining spatial capture of attention by salient stimuli has typically utilized stimuli that share a degree of relevance to the task participants are currently engaged in, such as distractors matching target features or appearing in a potential target location. Here, we test whether spatial attention can also be captured by distractor objects that are entirely irrelevant to the participants’ task, by recording EEG while participants carried out a task designed to be sensitive to measuring the PD component. Participants completed a letter search task, while ignoring lateralized visual (e.g., a dog), auditory (e.g., a dog’s bark), or simultaneous multisensory (e.g., dog image + sound) distractors. Results showed that visual and multisensory distractors elicited a PD component indicative of active lateralized distractor suppression. This ERP evidence of spatial attentional processing was observed in the absence of any behavioural distractor interference, suggesting effective early visual suppression. Interestingly, there was no evidence to suggest enhanced ability of multisensory distractors to compete for attentional selection, despite previous proposals of a ‘special’ saliency status for such items. Our results demonstrate that entirely irrelevant distractor stimuli are able to compete for spatial attention, while highlighting that such competition may not always be visible on behavioral measures alone.