Faculty of Science Research Talk : Uncovering The Neurophysiological Correlates of Inhibition of Return

Name: Dr Jason Satel – School of Psychology

Title: Uncovering The Neurophysiological Correlates of Inhibition of Return

Abstract : 

Inhibition of return (IOR) is a robust cognitive phenomenon whereby manual and oculomotor responses to target stimuli are slowed when the target location has been previously attended. IOR is thought to subserve novelty seeking and foraging facilitation in the real world. Two different forms of IOR have been identified – an input-based form when the oculomotor system is actively suppressed, and an output-based form when eye movements are allowed. The vast majority of previous work investigating IOR with event-related potentials (ERPs) has focused on the input-based form of IOR, given that eye movements are normally suppressed in ERP studies. In these studies, modulations of the early sensory P1 ERP component have been associated with behavioural IOR. However, recent work has demonstrated that when the eye movement system is activated – thereby eliciting the output-based, oculomotor form of IOR – P1 reductions are not correlated with behavioural IOR. Furthermore, output-based IOR is present, and equivalent, regardless of whether or not stimuli are presented as exogenous peripheral stimulations or endogenous central arrows, however, P1 reductions are only observed with peripheral stimuli. When retinotopic and spatiotopic coordinate systems are dissociated, P1 reductions are only found in the retinotopic condition, whereas oculomotor IOR is only found in the spatiotopic condition. This evidence suggests that P1 reductions are not a true correlate of oculomotor IOR. The later Nd ERP component, however, is also modulated in association with IOR in conditions using central arrows and spatiotopic coordinate systems. We therefore propose that P1 reductions are simply a result of repeated peripheral stimulation at the same location and they do not reflect oculomotor IOR. Later components, such as the Nd and possibly N2pc components, are more likely to reflect a neurophysiological measurement of true, oculomotor IOR.