N2pc modulation as an electrophysiological marker of output-based inhibitory cueing effects

An inhibitory cueing effect (ICE) is a phenomenon whereby behavioural responses (such as a manual keypress or saccade) to stimuli appearing at recently attended locations are slowed, provided that time elapsed is sufficient for the extinction of early facilitation effects. This phenomenon, often referred to as inhibition of return (IOR), is thought to be a functional component of visual search which facilitates novelty seeking. Research has demonstrated two dissociable mechanisms underlying ICEs – input-based and output-based. The present study used a modified spatial cueing task with both active and suppressed oculomotor-states, combined with electroencephalography (EEG) measurement, to investigate whether the deployment of covert visual attention (measured as the amplitude of N2pc) is modulated differentially by input and output-based ICEs. Additionally, the present study sought to examine the effect of attentional deficits on both behavioural inhibition (manual response times) and the modulation of deployed attention. Behavioural results showed that ICEs were elicited, however the observed inhibition was identical across oculomotor-state. The effect of group was marginally significant, with post-hoc analyses revealing a significant difference between uncued and cued targets in the control group (slower to cued), but only marginal significance for the deficit group. No significant results were found for N2pc analyses, however a polarity inverse to that expected was observed. Results, interpretations, and recommendations for future research are discussed.