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Stimulus-response incompatibility eliminates inhibitory cueing effects with saccadic but not manual responses

There are thought to be two forms of inhibition of return (IOR) depending on whether the oculomotor system is activated or suppressed. When saccades are allowed, output-based IOR is generated, whereas input-based IOR arises when saccades are prohibited. In a series of 4 experiments, we mixed or blocked compatible and incompatible trials with saccadic or manual responses to investigate whether cueing effects would follow the same pattern as those observed with more traditional peripheral onsets and central arrows. In all experiments, an uninformative cue was displayed, followed by a cue-back stimulus that was either red or green, indicating whether a compatible or incompatible response was required. The results showed that IOR was indeed observed for compatible responses in all tasks, whereas IOR was eliminated for incompatible trials—but only with saccadic responses. These findings indicate that the dissociation between input- and output-based forms of IOR depends on more than just oculomotor activation, providing further support for the existence of an inhibitory cueing effect that is distinct to the manual response modality.

Sensory adaptation and inhibition of return: dissociating multiple inhibitory cueing effects

Inhibition of return (IOR) refers to an increase in reaction times to targets that appeared at a previously cued location relative to an uncued location, often investigated using a spatial cueing paradigm. Despite numerous studies that have examined many aspects of IOR, the neurophysiological mechanisms underlying IOR are still in dispute. The objective of the current research is to investigate the plausible mechanisms by manipulating the cue and target types between central and peripheral stimuli in a traditional cue–target paradigm with saccadic responses to targets. In peripheral-cueing conditions, we observed inhibitory cueing effects across all cue–target onset asynchronies (CTOAs) with peripheral targets, but IOR was smaller and arose later with central targets. No inhibition was observed in central-cueing conditions at any CTOAs. Empirical data were simulated using a two-dimensional dynamic neural field model. Our results and simulations support previous work demonstrating that, at short CTOAs, behavioral inhibition is only observed with repeated stimulation—an effect of sensory adaptation. With longer CTOAs, IOR is observed regardless of target type when peripheral cueing is used. Our findings suggest that behaviorally exhibited inhibitory cueing effects can be attributed to multiple mechanisms, including both attenuation of visual stimulation and local inhibition in the superior colliculus.

Time course of inhibition of return in a spatial cueing paradigm with distractors

Studies of endogenous and exogenous attentional orienting in spatial cueing paradigms have been used to investigate inhibition of return, a behavioral phenomenon characterized by delayed reaction time in response to recently attended locations. When eye movements are suppressed, attention is covertly oriented to central or peripheral stimuli. Overt orienting, on the other hand, requires explicit eye movements to the stimuli. The present study examined the time course of slowed reaction times to previously attended locations when distractors are introduced into overt and covert orienting tasks. In a series of experiments, manual responses were required to targets following central and peripheral cues at three different cue-target intervals, with and without activated oculomotor systems. The results demonstrate that, when eye movements are suppressed, behavioral inhibition is reduced or delayed in magnitude by the presence of a distractor relative to conditions without distractors. However, the time course of behavioral inhibition when eye movements are required remains similar with or without distractors.

Influence of distractors on inhibition of return in a 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.