Influence of distractors on inhibition of return in spatial orienting paradigm

Inhibition of return (IOR) is a behavioural phenomenon whereby responses are inhibited at locations that have been previously stimulated when the time interval between stimulations is sufficiently long. Traditionally, a peripheral cue is presented at one location, then a peripheral target, requiring a manual or saccadic response, is presented at either the same (cued), or opposite (uncued), side as the cue. In this work, we have included distractors in a traditional spatial orienting paradigm where a non-target stimulus is presented at the opposite side of a target that requires a localization response (manual or saccadic). We investigate modulations of the behavioural cueing effects associated with the inclusion of distractors, as well the event-related potentials (ERPs) – specifically the early sensory P1 component – in this discrimination-localization task. Results demonstrate that IOR is observed behaviourally in such a paradigm, regardless of response modality, although it is larger with saccadic responses than manual responses. ERP results (with manual responses) did not show the common observation of early sensory P1 cueing effects in this paradigm when distractors are not included, perhaps due to the reduction of IOR in this paradigm. Future work should investigate modulations of ERP components when the oculomotor system is activated as well as look into the timecourse of the inhibitory cueing effects when distractors are included in a spatial orienting paradigm.