Saccadic Inhibition Of Return Research Articles

Fixation offset decreases pupillary inhibition of return

Inhibition of return (IOR) is reflected as a slower manual or saccadic response to a cued rather than an uncued target (manual IOR and saccadic IOR, respectively), and as a pupillary dilation when a bright, relative to a dark side of a display is cued (pupillary IOR). The aim of this study was to investigate the relation between an IOR and oculomotor system. According to the predominant view, only the saccadic IOR is strictly related to the visuomotor process, and the manual and pupillary IORs depend on non-motor factors (e.g., short-term visual depression). Alternatively, the after-effect of the covert-orienting hypothesis postulates that IOR is strictly related to the oculomotor system. As fixation offset affects oculomotor processes, this study investigated whether fixation offset also affects pupillary and manual IORs. The results show that fixation offset decreased IOR in pupillary but not manual responses, and provides support for the hypothesis that at least the pupillary IOR is tightly linked to eye movement preparation.

Inhibition of Return in Visual Search Does Not Rely on Spatial Working Memory.

Inhibition of return (IOR) prevents the immediate reorientation to previously attended locations, such that unattended locations are prioritized. In the current study, we were interested in whether saccadic IOR is affected by the storage of visuospatial information in working memory (WM) during a visual search task. To this end, participants searched a display for a target letter once while holding no, two, or four object locations in their spatial WM. During the search, either a previously inspected or an uninspected item was probed, and the participants were instructed to immediately saccade to this probed item before resuming the search. The results showed that saccadic latencies to previously inspected items were longer than to uninspected items, indicating the presence of IOR during the search. However, this effect was observed regardless of the number of item locations held in the spatial WM. This finding suggests that saccadic IOR does not rely on visuospatial WM in visual search.

No evidence for an independent retinotopic reference frame for inhibition of return

Inhibition of return (IOR) represents a delay in responding to a previously inspected location and is viewed as a crucial mechanism that sways attention toward novelty in visual search. Although most visual processing occurs in retinotopic, eye-centered, coordinates, IOR must be coded in spatiotopic, environmental, coordinates to successfully serve its role as a foraging facilitator. Early studies supported this suggestion but recent results have shown that both spatiotopic and retinotopic reference frames of IOR may co-exist. The present study tested possible sources for IOR at the retinotopic location including being part of the spatiotopic IOR gradient, part of hemifield inhibition and being an independent source of IOR. We conducted four experiments that alternated the cue-target spatial distance (discrete and contiguous) and the response modality (manual and saccadic). In all experiments, we tested spatiotopic, retinotopic and neutral (neither spatiotopic nor retinotopic) locations. We did find IOR at both the retinotopic and spatiotopic locations but no evidence for an independent source of retinotopic IOR for either of the response modalities. In fact, we observed the spread of IOR across entire validly cued hemifield including at neutral locations. We conclude that these results indicate a strategy to inhibit the whole cued hemifield or suggest a large horizontal gradient around the spatiotopically cued location. Public significance statementWe perceive the visual world around us as stable despite constant shifts of the retinal image due to saccadic eye movements. In this study, we explore whether Inhibition of return (IOR), a mechanism preventing us from returning to previously attended locations, operates in spatiotopic, world-centered or in retinal, eye-centered coordinates. We tested both saccadic and manual IOR at spatiotopic, retinotopic, and control locations. We did not find an independent retinotopic source of IOR for either of the response modalities. The results suggest that IOR spreads over the whole previously attended visual hemifield or there is a large horizontal spatiotopic gradient. The current results are in line with the idea of IOR being a foraging facilitator in visual search and contribute to our understanding of spatiotopically organized aspects of visual and attentional systems.

The gap effect reduces both manual and saccadic inhibition of return (IOR)

Inhibition of return (IOR) is the effect of slower responses to validly than invalidly cued targets. The discovery of IOR raised controversy as to whether it has two “flavors”, i.e., attentional/perceptual and motoric, or whether it is a homogeneous visual-motor phenomenon that should be understood in terms of the preparation of different effectors (mainly eye movement). Since manipulation of fixation offset (0 and 200 ms gap) is believed to affect the latency of saccades, we measured its influence on saccadic and manual IOR with a simple keypress response when eye movements were forbidden. In the two experiments which we carried out, the fixation offset decreased IOR in both the saccadic and the manual conditions. The results suggest the limitations of the attentional hypothesis, which assumes that manual IOR is independent of the motoric component; they are also in line with the tenets of the oculomotor hypothesis of IOR.

The contribution of forward masking to saccadic inhibition of return

Inhibition of return is the name typically given to the prolonged latency of motor responses directed to a previously cued target location. There is intense debate about the origins of this effect and its function, but most take for granted (despite lack of evidence) that it depends little on forward masking. Therefore, we re-examined the role of forward masking in inhibition of return. Forward masking was indexed by slower saccadic reaction times (SRTs) when the target orientation repeated the cue orientation at the same location. We confirmed effects of orientation repetition in the absence of an attentional bias when cues were presented on both sides of fixation (bilateral presentation). The effect of orientation repetition was reduced with high target contrast, consistent with a low-level origin such as contrast gain control in early visual areas. When presenting cues on only one side of fixation (unilateral presentation), we obtained inhibition of return with longer cue-target intervals and facilitation with targets presented shortly after the cue. The effect of orientation repetition was reduced when facilitation was observed, but was as strong as with bilateral cues when inhibition of return was observed. Therefore, forward masking may contribute to the inhibition of return effect by delaying reaction times to repeated features at the same location, but is not a principal cause of inhibition of return; in agreement with previous views.Significance statementThe saccadic inhibition of return effect is a reaction-time cost when responding to a pre-cued location. Additional object updating costs are typically invoked to explain reaction-time costs observed when cue and target have the same shape. Yet, lower-level, forward masking of the target by the cue can not be ruled out. Importantly, we show an effect of orientation repetition that is consistent with low-level forward masking rather than object updating costs and that does not interact with inhibition of return.

Multiple Diffusion Models to Compare Saccadic and Manual Responses for Inhibition of Return.

Cuing a location in space produces a short-lived advantage in reaction time to targets at that location. This early advantage, however, switches to a reaction time cost and has been termed inhibition of return (IOR). IOR behaves differently for different response modalities, suggesting that it may not be a unified effect. This letter presents new data from two experiments testing the gradient of IOR with random, continuous cue-target Euclidean distance and cue-target onset asynchrony. These data were then used to train multiple diffusion models of saccadic and manual reaction time for these cuing experiments. Diffusion models can generate accurate distributions of reaction time data by modeling a response as a buildup of evidence toward a response threshold. If saccadic and attentional IOR are based on similar processes, then differences in distribution will be best explained by adjusting parameter values such as signal and noise within the same model structure. Although experimental data show differences in the timing of IOR across modality, best-fit models are shown to have similar model parameters for the gradient of IOR, suggesting similar underlying mechanisms for saccadic and manual IOR.

Reduced saccadic inhibition of return to moving eyes in autism spectrum disorders

Inhibition of Return (IOR) refers to slower reaction time to a target presented at the same location as a preceding stimulus. Here, we examine reflexive attention orienting via the saccadic IOR using a shift in gaze direction (i.e. from averted to direct) in faces presented as a peripheral cue, in upright and inverted orientations, in adults with Autism Spectrum Disorder (ASD) and typically developed comparison participants. While both groups showed an IOR in the inverted face condition, this effect was reduced in participants with ASD in the upright face condition, as compared to comparison participants, suggesting that moving eyes do not trigger reflexive exogenous orienting in individuals with ASD. Impaired reflexive orienting to eye gaze might severely compromise the later development of social functions in ASD, such as joint attention, face emotion recognition and mindreading.

Accelerated time course of saccadic inhibition of return in individuals with autism spectrum disorders.

The inhibition of return (IOR) refers the observer's slower response time when the target stimulus appears on the previously attended location. In the present study, we examined the time course of saccadic IOR by using five stimuli onset asynchronies (SOAs) in a group of adults with autism spectrum disorders (ASDs) and a comparison group. The results showed that the IOR effect occurred earlier (300 ms SOA) in participants with ASDs, relative to the comparison participants (500 and 700 ms SOAs). The ASD group also committed a greater number of anticipatory saccades, which positively correlated with scores on restricted and repetitive behaviors, as assessed by the Autism Diagnostic Interview-Revised (ADI-R; Lord et al. in J Autism Dev Disord 24:659-685, 1994). These findings reveal an accelerated time course for saccadic IOR along with diminished volitional oculomotor control in participants with ASDs. We discussed these results with reference to the atypical and the superior visual search abilities often reported in this population.

Cortical control of Inhibition of Return: Exploring the causal contributions of the left parietal cortex

Inhibition of Return (IOR) refers to longer response times (RTs) when processing information from an already inspected spatial location. This effect encourages orienting towards novel locations and may be hence adaptive to efficiently explore our environment. In a previous study (Bourgeois, Chica, Valero-Cabre, & Bartolomeo, 2013), we demonstrated that repetitive Transcranial Magnetic Stimulation (rTMS) over right hemisphere parietal sites, such as the intra-parietal sulcus (IPS), or the temporo-parietal junction (TPJ), lastingly interfered with manual but not saccadic IOR, for ipsilateral right-sided targets. For contralateral left-sided targets, rTMS over the right IPS, but not over the right TPJ, impaired both manual and saccadic IOR. In the present study, we investigated hemispheric differences in the cortical control of IOR by stimulating left parietal sites with the same design. Contrary to the stimulation of the right hemisphere, rTMS over the left IPS or TPJ did not produce significant modulations of either manual or saccadic IOR. This evidence extends to IOR the validity of current models of hemispheric asymmetries in the control of visuospatial attention.

Saccadic Inhibition of Return After Attention Shifts to Relevant and Irrelevant Color Singletons

Saccadic Inhibition of Return After Attention Shifts to Relevant and Irrelevant Color Singletons

Motor inhibition of return can affect prepared reaching movements

Inhibition of return (IOR) is a widely studied phenomenon that is thought to affect attention, eye movements, or reaching movements, in order to promote orienting responses toward novel stimuli. Previous research in our laboratory demonstrated that the motor form of saccadic IOR can arise from late-stage response execution processes. In the present study, we were interested in whether the same is true of reaching responses. If IOR can emerge from processes operating at or around the time of response execution, then IOR should be observed even when participants have fully prepared their responses in advance of the movement initiation signal. Similar to the saccadic system, our results reveal that IOR can be implemented as a late-stage execution bias in the reaching control system.

Cortical control of inhibition of return: Causal evidence for task-dependent modulations by dorsal and ventral parietal regions

Inhibition of return (IOR) reflects a bias to preferentially attend to non-previously attended or inspected spatial locations. IOR is paramount to efficiently explore our environment, by avoiding repeated scanning of already visited locations. Patients with left visual neglect after right parietal damage or fronto-parietal disconnection demonstrated impaired manual, but not saccadic, IOR for right-sided targets (Bourgeois et al., 2012). Here we aimed at investigating in healthy participants the causal role of distinct cortical sites within the right hemisphere in manual and saccadic IOR, by evaluating the offline effects of repetitive Transcranial Magnetic Stimulation (rTMS) on the right intra-parietal sulcus (IPS) and the right temporo-parietal junction (TPJ). Our results show that rTMS over both sites lastingly interfered with manual but not saccadic IOR for right-sided targets. This behavioral pattern closely mimicked the performance of neglect patients evaluated with the same paradigm. In contrast, for left-sided targets, rTMS over the right IPS impaired both manual and saccadic IOR, while rTMS over the right TPJ produced no modulation in either task. We concluded that distinct parietal nodes of the dorsal and ventral spatial attention networks of the right hemisphere make different contributions to exogenous orienting processes implicated in IOR, and that such effects are hemifield- and task-dependent.

Saccadic inhibition of return can arise from late-stage execution processes

Inhibition of return (IOR) is thought to improve the efficiency of visual search behaviour by biasing attention, eye movements, or both, toward novel stimuli. Previous research suggests that IOR might arise from early sensory, attentional or motor programming processes. In the present study, we were interested in determining if IOR could instead arise from processes operating at or during response execution, independent from effects on earlier processes. Participants made consecutive saccades (from a common starting location) to central arrowhead stimuli. We removed the possible contribution of early sensory/attentional and motor preparation effects in IOR by allowing participants to fully prepare their responses in advance of an execution signal. When responses were prepared in advance, we continued to observe IOR. Our data therefore provide clear evidence that saccadic IOR can result from an execution bias that might arise from inhibitory effects on motor output neurons, or alternatively from late attentional engagement processes.

Inhibition of Return after Color Singletons

Inhibition of return (IOR) is the faster selection of hitherto unattended than previously attended positions. Some previous studies failed to find evidence for IOR after attention capture by color singletons. Others, however, did report IOR effects after color singletons. The current study examines the role of cue relevance for obtaining IOR effects. By using a potentially more sensitive method – saccadic IOR – we tested and found IOR after relevant color singleton cues that required an attention shift (Experiment 1). In contrast, irrelevant color singletons failed to produce reliable IOR effects in Experiment 2. Also, Experiment 2 rules out an alternative explanation of our IOR findings in terms of masking. We discuss our results in light of pertaining theories of IOR.

Perceptual and motor inhibition of return: components or flavors?

The most common evidence for inhibition of return (IOR) is the robust finding of increased response times to targets that appear at previously cued locations following a cue-target interval exceeding ~300 ms. In a variation on this paradigm, Abrams and Dobkin (Journal of Experimental Psychology: Human Perception and Performance 20:467-477, 1994b) observed that IOR was greater when measured with a saccadic response to a peripheral target than with that to a central arrow, leading to the conclusion that saccadic responses to peripheral targets comprise motoric and perceptual components (the two-components theory for saccadic IOR), whereas saccadic responses to a central target comprise a single motoric component. In contrast, Taylor and Klein (Journal of Experimental Psychology: Human Perception and Performance 26:1639-1656, 2000) discovered that IOR for saccadic responses was equivalent for central and peripheral targets, suggesting a single motoric effect under these conditions. Rooted in methodological differences between the studies, three possible explanations for this discrepancy can be found in the literature. Here, we demonstrate that the empirical discrepancy is rooted in the following methodological difference: Whereas Abrams and Dobkin (Journal of Experimental Psychology: Human Perception and Performance 20:467-477, 1994b) administered central arrow and peripheral onset targets in separate blocks, Taylor and Klein (Journal of Experimental Psychology: Human Perception and Performance 26:1639-1656, 2000) randomly intermixed these stimuli in a single block. Our results demonstrate that (1) blocking central arrow targets fosters a spatial attentional control setting that allows for the long-lasting IOR normally generated by irrelevant peripheral cues to be filtered and (2) repeated sensory stimulation has no direct effect on the magnitude of IOR measured by saccadic responses to targets presented about 1 s after a peripheral cue.

Cortical control of inhibition of return: Evidence from patients with inferior parietal damage and visual neglect

Inhibition of return (IOR) refers to slower reaction times to targets presented at previously stimulated or inspected locations. This phenomenon biases orienting towards novel locations and is functional to an effective exploration of the environment. Patients with right brain damage and left visual neglect explore their environment asymmetrically, with strong difficulties to orient attention to left-sided objects. We show for the first time a dissociation between manual and saccadic IOR in neglect. Our patients demonstrated facilitation, instead of inhibition, for repeated right-sided targets with manual responses, but normal IOR to right-sided targets with saccadic responses. All neglect patients had damage to the supramarginal gyrus in the right parietal lobe, or to its connections with the ipsilateral prefrontal cortex. We concluded that IOR with manual responses relies on fronto-parietal attentional networks in the right hemisphere, whose functioning is typically impaired in neglect patients. Saccadic IOR may instead depend on circuits less likely to be damaged in neglect, such as the retinotectal visual pathway.

Spatial working memory load impairs manual but not saccadic inhibition of return

Although spatial working memory has been shown to play a central role in manual IOR (Castel, Pratt, & Craik, 2003), it is so far unclear whether spatial working memory is involved in saccadic IOR. The present study sought to address this question by using a dual task paradigm, in which the participants performed an IOR task while keeping a set of locations in spatial working memory. While manual IOR was eliminated, saccadic IOR was not affected by spatial working memory load. These findings suggest that saccadic IOR does not rely on spatial working memory to process inhibitory tagging.

Evidence for an attentional component in saccadic inhibition of return

Evidence for an attentional component in saccadic inhibition of return

Evidence for an attentional component in saccadic inhibition of return

After presentation of a peripheral cue, facilitation at the cued location is followed by inhibition of return (IOR). It has been recently proposed that IOR may originate at different processing stages for manual and ocular responses, with manual IOR resulting from inhibited attentional orienting, and ocular IOR resulting form inhibited motor preparation. Contrary to this interpretation, we found an effect of target contrast on saccadic IOR. The effect of contrast decreased with increasing reaction times (RTs) for saccades, but not for manual key-press responses. This may have masked the effect of contrast on IOR with saccades in previous studies (Hunt and Kingstone in J Exp Psychol Hum Percept Perform 29:1068-1074, 2003) because only mean RTs were considered. We also found that background luminance strongly influenced the effects of gap and target contrast on IOR.

Inhibition of return in single and dual tasks: Examining saccadic, keypress, and pointing responses

Two experiments are reported in which inhibition of return (IOR)was examined wit h single-responsetasks (either manual responses alone or saccadic responses alone) and dual-response tasks (simultaneous manual and saccadic responses). The first experiment-using guided limb movements that require considerable spatial information-showed more IOR for saccades than for pointing responses. In addition, saccadic IOR was reduced with concurrent pointing movements, but manual IOR was not affected by concurrent saccades. Importantly, at the time of saccade initiation, the arm movements did not start yet, indicating that the influence on saccade IOR is due to arm-movement preparation. In the second experiment, using localization keypress responses that required only minimal spatial information, greater IOR was again found for saccadic than for manual responses, but no effect of concurrent movements was found. These findings add further support that there is a dissociation between oculomotor and skeletal-motor IOR. Moreover, the results show that the preparation manual responses tend to mediate saccadic behavior-but only when the manual responses require high levels of spatial accuracy-and that the superior colliculus is the likely neural substrate integrating IOR for eye and arm movements.