Oculomotor Inhibition Research Articles

The influence of spatial congruency and movement preparation time on saccade curvature in simultaneous and sequential dual-tasks

Saccade curvature represents a sensitive measure of oculomotor inhibition with saccades curving away from covertly attended locations. Here we investigated whether and how saccade curvature depends on movement preparation time when a perceptual task is performed during or before saccade preparation. Participants performed a dual-task including a visual discrimination task at a cued location and a saccade task to the same location (congruent) or to a different location (incongruent). Additionally, we varied saccade preparation time (time between saccade cue and Go-signal) and the occurrence of the discrimination task (during saccade preparation=simultaneous vs. before saccade preparation=sequential). We found deteriorated perceptual performance in incongruent trials during simultaneous task performance while perceptual performance was unaffected during sequential task performance. Saccade accuracy and precision were deteriorated in incongruent trials during simultaneous and, to a lesser extent, also during sequential task performance. Saccades consistently curved away from covertly attended non-saccade locations. Saccade curvature was unaffected by movement preparation time during simultaneous task performance but decreased and finally vanished with increasing movement preparation time during sequential task performance. Our results indicate that the competing saccade plan to the covertly attended non-saccade location is maintained during simultaneous task performance until the perceptual task is solved while in the sequential condition, in which the discrimination task is solved prior to the saccade task, oculomotor inhibition decays gradually with movement preparation time.

The Effects of Task- and Switch-Predictability on Oculomotor Inhibition of Return During Visual Search

The Effects of Task- and Switch-Predictability on Oculomotor Inhibition of Return During Visual Search

Rewards modulate saccade latency but not exogenous spatial attention.

The eye movement system is sensitive to reward. However, whilst the eye movement system is extremely flexible, the extent to which changes to oculomotor behavior induced by reward paradigms persist beyond the training period or transfer to other oculomotor tasks is unclear. To address these issues we examined the effects of presenting feedback that represented small monetary rewards to spatial locations on the latency of saccadic eye movements, the time-course of learning and extinction of the effects of rewarding saccades on exogenous spatial attention and oculomotor inhibition of return. Reward feedback produced a relative facilitation of saccadic latency in a stimulus driven saccade task which persisted for three blocks of extinction trials. However, this hemifield-specific effect failed to transfer to peripheral cueing tasks. We conclude that rewarding specific spatial locations is unlikely to induce long-term, systemic changes to the human oculomotor or attention systems.

Alcohol-related and negatively valenced cues increase motor and oculomotor disinhibition in social drinkers.

Our aim in the present study was to investigate the psychological mechanisms that underlie the disinhibiting effects of alcohol cues in social drinkers by contrasting motor and oculomotor inhibition after exposure to alcohol-related, emotional, and neutral pictures. We conducted 2 studies in which social drinkers completed modified stop-signal (laboratory) and antisaccade (online) tasks in which positive, negative, alcohol-related, and neutral pictures were embedded. We measured cue-specific disinhibition in each task, and investigated whether sex and drinking status moderated the effects of pictures on disinhibition. Across both studies, comparable increases in disinhibition were observed in response to both alcohol and negatively valenced pictures, relative to both positive and neutral pictures. These differences in disinhibition could not be explained by differences between picture sets in arousal or valence ratings. There was no clear evidence of moderation by sex or drinking status. Secondary analyses demonstrated that alcohol-specific disinhibition was not reliably associated with individual differences in alcohol consumption or craving. These results suggest that the disinhibiting properties of alcohol-related cues cannot be attributed solely to their valence or arousing properties, and that alcohol cues may have unique disinhibiting properties.

Dissociating temporal inhibition of return and saccadic momentum across multiple eye-movement tasks.

Saccade latencies are longer prior to an eye movement to a recently fixated location than to control locations, a phenomenon known as oculomotor inhibition of return (O-IOR). There are theoretical reasons to expect that O-IOR would vary in magnitude across different eye movement tasks, but previous studies have produced contradictory evidence. However, this may have been because previous studies have not dissociated O-IOR and a related phenomenon, saccadic momentum, which is a bias to repeat saccade programs that also influences saccade latencies. The present study dissociated the influence of O-IOR and saccadic momentum across three complex visual tasks: scene search, scene memorization, and scene aesthetic preference. O-IOR was of similar magnitude across all three tasks, while saccadic momentum was weaker in scene search.

Dissociating temporal inhibition of return and saccadic momentum across multiple eye-movement tasks

Saccade latencies are longer before eye movements to recently fixated locations, a phenomenon known as oculomotor inhibition of return (O-IOR). However, latencies are also influenced by saccadic momentum: latencies are shortest before forward saccades and increase as the angular deviation (difference in direction) of the current and previous saccades increases. Using a within-subjects and within-items design, the present study attempted to dissociate the temporal and spatial consequences of O-IOR and saccadic momentum across three tasks: scene search, scene memorization, and aesthetic preference. Spatial analyses revealed facilitation of return (rather than inhibition) in all tasks: return saccades were more frequent in the data compared to a shuffled baseline. Initial temporal analyses suggested that O-IOR was weaker in search (16 ms) than in memorization or preference (28 & 25 ms, respectively). Saccadic momentum appears even if previous and current saccades are not closely matched in amplitude, while O-IOR appears only when saccades are matched in amplitude so the current saccade lands within the zone of IOR (within 4° of the previous fixation location), making it possible to dissociate the two phenomena. Fixation durations increased linearly as a function of angular deviation outside the IOR zone, but curvilinearly within the zone of IOR, revealing an additional penalty for return saccades beyond that accounted for by saccadic momentum. Furthermore, saccadic momentum and O-IOR differentially affected the frequency distribution of fixation durations. Saccadic momentum shifted the mean of the distribution's Gaussian component, lengthening most fixations, while O-IOR only influenced the skewness of the distribution (the exponential component), lengthening a subset of fixations. Interestingly, when dissociated in this way, O-IOR was equivalent in magnitude across tasks while saccadic momentum was not present in search. These results suggest that O-IOR and saccadic momentum are independent phenomena, and that O-IOR is task-independent while saccadic momentum is not. Meeting abstract presented at VSS 2014

Oculomotor task switching: alternating from a nonstandard to a standard response yields the unidirectional prosaccade switch-cost.

The completion of an antisaccade (i.e., a nonstandard task) lengthens the reaction time (RT) of a subsequent prosaccade: a behavioral phenomenon termed the unidirectional prosaccade switch-cost. One explanation for the unidirectional prosaccade switch-cost is suppressing a stimulus-driven prosaccade during the preceding antisaccade trial engenders a residual inhibition of the oculomotor networks that support prosaccade planning (i.e., the oculomotor inhibition hypothesis). Alternatively, the unidirectional prosaccade switch-cost may reflect the persistent activation of the antisaccade's nonstandard task rules (i.e., task set), which delays the planning of the next prosaccade (i.e., task-set inertia hypothesis). To determine which hypothesis provides the most parsimonious account for the unidirectional prosaccade switch-cost, participants alternated between pro- and antisaccades wherein task instructions (i.e., pro- and antisaccade) were provided before (i.e., classic cuing) or concurrent (i.e., delayed cuing) with response cuing. Importantly, pro- and antisaccades elicited via the delayed cuing condition required the suppression of a stimulus-driven prosaccade at response cuing (i.e., response suppression) to discern the appropriate to-be-performed task. Results showed that classic and delayed antisaccades, but not delayed prosaccades, lengthened the RT of subsequent prosaccades. That delayed prosaccades, which require response suppression for their successful execution, did not lengthen the RT of subsequent prosaccades indicates that the oculomotor inhibition hypothesis does not account for the unidirectional prosaccade switch-cost. Instead, the current findings are in line with the assertion that the task set associated with a nonstandard antisaccade persists inertially and delays the planning of a subsequent prosaccade (i.e., task-set inertia hypothesis).

In search of a reliable electrophysiological marker of oculomotor inhibition of return.

Inhibition of return (IOR) operationalizes a behavioral phenomenon characterized by slower responding to cued, relative to uncued, targets. Two independent forms of IOR have been theorized: input-based IOR occurs when the oculomotor system is quiescent, while output-based IOR occurs when the oculomotor system is engaged. EEG studies forbidding eye movements have demonstrated that reductions of target-elicited P1 components are correlated with IOR magnitude, but when eye movements occur, P1 effects bear no relationship to behavior. We expand on this work by adapting the cueing paradigm and recording event-related potentials: IOR is caused by oculomotor responses to central arrows or peripheral onsets and measured by key presses to peripheral targets. Behavioral IOR is observed in both conditions, but P1 reductions are absent in the central arrow condition. By contrast, arrow and peripheral cues enhance Nd, especially over contralateral electrode sites.

Oculomotor Inhibition of Return in Real World Scene Search

Oculomotor Inhibition of Return in Real World Scene Search

'Don't Look' Inhibition: Attentional and oculomotor inhibition at locations forbidden to saccades

'Don't Look' Inhibition: Attentional and oculomotor inhibition at locations forbidden to saccades

Temporal Oculomotor Inhibition of Return and Spatial Facilitation of Return in a Visual Encoding Task

*Correspondence: John M. Henderson, Visual Cognition Laboratory, Institute for Mind and Brain and Department of Psychology, University of South Carolina, 1800 Gervais Street, Columbia, SC 29208, USA e-mail: john.henderson@sc.edu Oculomotor inhibition of return (O-IOR) is an increase in saccade latency prior to an eye movement to a recently fixated location compared to other locations. It has been proposed that this temporal O-IOR may have spatial consequences, facilitating foraging by inhibiting return to previously attended regions. In order to test this possibility, participants viewed arrays of objects and of words while their eye movements were recorded.Temporal O-IOR was observed, with equivalent effects for object and word arrays, indicating that temporal O-IOR is an oculomotor phenomenon independent of array content.There was no evidence for spatial inhibition of return (IOR). Instead, spatial facilitation of return was observed: participants were significantly more likely than chance to make return saccades and to refixate just-visited locations. Further, the likelihood of making a return saccade to an object or word was contingent on the amount of time spent viewing that object or word before leaving it. This suggests that, unlike temporal O-IOR, return probability is influenced by cognitive processing. Taken together, these results are inconsistent with the hypothesis that IOR functions as a foraging facilitator. The results also provide strong evidence for a different oculomotor bias that could serve as a foraging facilitator: saccadic momentum, a tendency to repeat the most recently executed saccade program.We suggest that models of visual attention could incorporate saccadic momentum in place of IOR.

Delayed oculomotor inhibition in patients with lesions to the human frontal oculomotor cortex: Evidence from a study on saccade averaging

The frontal oculomotor cortex is known to play an important role in oculomotor selection. The aim of the current study was to examine whether previously observed findings concerning the role of the frontal oculomotor cortex in the speed of saccade initiation and oculomotor inhibition might be related to a common underlying role of these areas in oculomotor selection. To this end, six patients with lesions to the frontal oculomotor cortex performed a double stimulus paradigm in which two elements were presented simultaneously in close proximity. Patients performed a block in which no specific task instruction was given and a block in which an instruction was provided about which of the two elements was the target. The rationale behind this manipulation was that the introduction of a specific task instruction would require a stronger involvement of top-down factors. In contrast to the block without a specific task instruction, saccade latencies to the contralesional visual field were longer than the ipsilesional visual field when a task instruction was given. This effect was strongest for saccades that landed away from the target and the distractor, reflecting trials in which strong oculomotor inhibition was applied. The observed deficits can be explained in terms of a slowing of the inhibitory signals associated with the rejection of a distractor. Given the known role of the Frontal Eye Fields and the location of the lesions, we attribute these findings to the Frontal Eye Fields, revealing their important role in the voluntary control of eye movements.

Cultural influences on oculomotor inhibition of remote distractors: Evidence from saccade trajectories

This study investigated whether low-level attentional processes as indicated by saccade trajectories are modulated by higher-order factors as indicated by participants' cultural background. We hypothesized that if the East Asian participants engage in context-dependent attentional processing to a greater extent than the Western participants, then the magnitude of the distractor effect on saccade trajectories (Doyle & Walker, 2001) should be larger with the East Asian participants than with the Western participants. Participants executed vertical saccades towards targets presented on the vertical meridian above or below fixation. Simultaneously with the target, a distractor appeared in one of the screen quadrants. Consistently with our hypothesis, we found evidence that the saccades of the Chinese participants tended to curve away from the distractors more strongly than the saccades of the German participants. However, this effect was restricted to the upper distractors and the lower targets. The findings are discussed in terms of cross-cultural differences in distractor-related activation and inhibition and functional specialization of hemifields.

The effects of cue-specific inhibition training on alcohol consumption in heavy social drinkers.

Training social drinkers to exercise motor inhibitory control leads to a reduction in alcohol consumption. However, it is unclear if participants should attempt to exercise inhibitory control in the presence of alcohol-related cues or if nonspecific inhibition training is equally effective. It is also unclear if comparable effects can be demonstrated by training oculomotor inhibitory control. We trained motor inhibition in the context of a modified stop-signal task (experiment 1) and oculomotor inhibition in the context of a modified antisaccade task (experiment 2) before investigating the influence of these manipulations on alcohol consumption. Results from experiment 1 demonstrated that training motor inhibition in the presence of alcohol-related cues led to reduced ad libitum alcohol consumption in the laboratory but not self-reported drinking in the week after training. These effects were seen in contrast to a control group that received no inhibition training and another control group that was trained to inhibit only in the presence of neutral cues; alcohol consumption did not differ between the latter two groups. In experiment 2, training of oculomotor inhibition in the presence of alcohol-related cues led to slowed eye movements toward target cues on catch trials, but it did not influence the proportion of inhibitory failures and had no influence on alcohol consumption in the laboratory. We conclude that training participants to exercise inhibitory control in the presence of alcohol-related cues can reduce alcohol consumption, but the effects are transient and are only seen when motor, but not oculomotor, inhibition is trained.

Temporal oculomotor inhibition of return and spatial facilitation of return in a visual encoding task

Oculomotor inhibition of return (O-IOR) is an increase in saccade latency prior to an eye movement to a recently fixated location compared to other locations. It has been proposed that this temporal O-IOR may have spatial consequences, facilitating foraging by inhibiting return to previously attended regions. In order to test this possibility, participants viewed arrays of objects and of words while their eye movements were recorded. Temporal O-IOR was observed, with equivalent effects for object and word arrays, indicating that temporal O-IOR is an oculomotor phenomenon independent of array content. There was no evidence for spatial inhibition of return (IOR). Instead, spatial facilitation of return was observed: participants were significantly more likely than chance to make return saccades and to re-fixate just-visited locations. Further, the likelihood of making a return saccade to an object or word was contingent on the amount of time spent viewing that object or word before leaving it. This suggests that, unlike temporal O-IOR, return probability is influenced by cognitive processing. Taken together, these results are inconsistent with the hypothesis that IOR functions as a foraging facilitator. The results also provide strong evidence for a different oculomotor bias that could serve as a foraging facilitator: saccadic momentum, a tendency to repeat the most recently executed saccade program. We suggest that models of visual attention could incorporate saccadic momentum in place of IOR.

Oculomotor inhibition of return in normal and mindless reading

Oculomotor inhibition of return (O-IOR) is an increase in saccade latency prior to an eye movement to a recently fixated location, as compared with other locations. To investigate O-IOR in reading, subjects participated in two conditions while their eye movements were recorded: normal reading and mindless reading with words replaced by geometric shapes. We investigated the manifestation of O-IOR in reading and whether it is related to extracting meaning from the text or is an oculomotor phenomenon. The results indicated that fixation durations prior to a saccade returning to the immediately preceding fixated word were longer than those to other words, consistent with O-IOR. Furthermore, fixation durations were longest prior to a saccade that returned the eyes to the specific character position in the word that had previously been fixated and dropped off as the distance between the previously fixated character and landing position increased. This result is consistent with the hypothesis that O-IOR is relatively precise in its application during reading and drops off as a gradient. Both of these results were found for text reading and for mindless reading, suggesting that they are consequences of oculomotor control, and not of language processing. Finally, although these temporal IOR effects were robust, no spatial consequences of IOR were observed: Previously fixated words and characters were as likely to be refixated as new words and characters.

Oculomotor Inhibition of Return in Normal and Mindless Reading

Oculomotor inhibition of return (O-IOR) is an increase in saccade latency prior to an eye movement to a recently fixated location compared to other locations. To investigate O-IOR in reading, subjects participated in two conditions while their eye movements were recorded: normal reading, and mindless reading in which words were replaced by equivalent geometric shapes. We investigated the manifestation of O-IOR in reading, and whether it is related to extracting meaning from the text or is a purely oculomotor phenomenon. The results indicated that fixation durations prior to a saccade returning to the last fixated word were longer than to other words, consistent with O-IOR. Furthermore, this effect was spatially specific: Fixation durations were longest prior to a saccade that returned the eyes to the character in the word that had previously been fixated, and dropped off as the distance between the previously fixated character and landing position increased. This result is consistent with the hypothesis that IOR is applied to the fixated character location during reading and drops off as a spatial gradient. Both of these results were found for text reading and for mindless reading, suggesting that they are consequences of oculomotor control and not of language processing. Finally, although the temporal IOR effects were robust, no spatial consequences of IOR were observed: Previously fixated words and characters were as likely to be re-fixated as new words and characters. Meeting abstract presented at VSS 2012

Antisaccade performance in Korsakoff patients reveals deficits in oculomotor inhibition

Oculomotor inhibition reflects the ability to suppress an unwanted eye movement. The goal of the present study was to assess oculomotor inhibition in patients with Korsakoff's syndrome (KS). To this end, an antisaccade task was employed in which an eye movement towards an onset stimulus has to be inhibited, and a voluntary saccade has to be executed in the opposite direction. Compared to the results of a matched control group, patients showed a higher percentage of intrusive saccades, made more antisaccade errors, and showed longer latencies on prosaccade trials. These results clearly show that oculomotor inhibition is impaired in KS. Part of these deficits in oculomotor inhibition may be explained by neuronal atrophy in the frontal areas, which is generally associated with KS.

Oculomotor inhibition of return: How soon is it “recoded” into spatiotopic coordinates?

When, in relation to the execution of an eye movement, does the recoding of visual information from retinotopic to spatiotopic coordinates happen? Two laboratories seeking to answer this question using oculomotor inhibition of return (IOR) have generated different answers: Mathôt and Theeuwes (Psychological Science 21:1793-1798, 2010) found evidence for the initial coding of IOR to be retinotopic, while Pertzov, Zohary, and Avidan (Journal of Neuroscience 30:8882-8887, 2010) found evidence for spatiotopic IOR at even shorter postsaccadic intervals than were tested by Mathôt and Theeuwes (Psychological Science 21:1793-1798, 2010). To resolve this discrepancy, we conducted two experiments that combined the methods of the previous two studies while testing as early as possible. We found early spatiotopic IOR in both experiments, suggesting that visual events, including prior fixations, are typically coded into an abstract, allocentric representation of space either before or during eye movements. This type of coding enables IOR to encourage orienting toward novelty and, consequently, to perform the role of a foraging facilitator.

Upper–lower visual field asymmetries in oculomotor inhibition of emotional distractors

The present study investigated oculomotor inhibition of emotional faces as indicated by saccade curvatures. In Experiment 1, participants saccaded towards a target that appeared above or below fixation while single facial distractors depicting neutral, happy, and angry expressions appeared in one of the four quadrants of the screen. In Experiment 2, participants selected between two objects on the screen by saccading towards a predefined target, while again single facial emotional distractors were presented in one of the four screen quadrants. In both experiments, saccade trajectories curved most strongly away from angry distractors indicating enhanced attentional capture by angry faces. This effect occurred with upright faces but not with inverted faces. The emotion effect was restricted to targets at the lower vertical meridian. The lower visual field has been argued to be specialized for action in peripersonal space and near vision. The modulation by target location might be attributed to activation of near space representation by saccades toward a lower target, inducing increased vigilance for stimuli of action relevance to protect the peripersonal space from interference.