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Fluctuations in a person's arousal accompany mental states such as drowsiness, mental effort, or motivation, and have a profound effect on task performance. Here, we investigated the link between two central instances affected by arousal levels, heart rate and eye movements. In contrast to heart rate, eye movements can be inferred remotely and unobtrusively, and there is evidence that oculomotor metrics (i.e., fixations and saccades) are indicators for aspects of arousal going hand in hand with changes in mental effort, motivation, or task type. Gaze data and heart rate of 14 participants during film viewing were used in Random Forest models, the results of which show that blink rate and duration, and the movement aspect of oculomotor metrics (i.e., velocities and amplitudes) link to heart rate-more so than the amount or duration of fixations and saccades. We discuss that eye movements are not only linked to heart rate, but they may both be similarly influenced by the common underlying arousal system. These findings provide new pathways for the remote measurement of arousal, and its link to psychophysiological features., Competing Interests: The authors have declared that no competing interests exist.

Saccades toward previously cued or fixated locations typically have longer latencies than those toward novel locations, a phenomenon known as inhibition of return (IOR). Despite extensive debate on its potential function, it remains unclear what the role of IOR in the oculomotor decision process is. Here, we ask whether the effect on eye movement planning is best characterized as a delay in visual target discrimination or as a reduction in readiness to execute the movement (saccade readiness). To evaluate this question, we use target-distractor tasks with clear speed-accuracy trade-offs. Simultaneously cueing both the target and distractor (or neither) we find longer latencies at the cued locations. Despite this delay in latencies, accuracy improves in line with the speed-accuracy trade-off curve (Experiment 1). This suggests that while visual target discrimination can progress unimpeded, saccade readiness is reduced. Based on this reduction in readiness we predict that the more saccades rely on visual target discrimination, the less their destination will be affected by inducing IOR. Indeed, after cueing either the target or an onset distractor (Experiment 2), short-latency, stimulus-driven, saccades are strongly biased away from the cued location, while the destinations of longer latency goal-driven saccades are affected only minimally. The fact that primarily stimulus-driven saccades are affected by inducing IOR is interesting as it can explain why the spatial bias associated with IOR is not consistently found. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Before looking at or reaching for an object, the focus of attention is first allocated to the movement object. Here we investigated whether the strength of these pre-motor shifts of attention cumulates if an object is targeted by multiple effectors (eyes and hands). A total of 29 participants were tested on a visuomotor task. They were cued to move gaze, the left hand, right hand, or both (one to three effectors) to a common object or to different peripheral objects. Before the movements, eight possible objects briefly changed form, of which one was a distinct probe. Results showed that the average recognition of the probe's identity change increased as more effectors targeted this object. For example, performance was higher when two hands as compared to one hand were moved to the probe. This effect remained evident despite the detrimental effect on performance of the increase in motor task complexity of moving two hands as compared to one hand. The accumulation of recognition improvements as a function of the number of effectors that successfully target the probe points at parallel and presumably independent mechanisms for hand- and eye-coordination that evoke pre-motor shifts of attention.

Since the seminal work of Yarbus, multiple studies have demonstrated the influence of task-set on oculomotor behavior and the current cognitive state. In more recent years, this field of research has expanded by evaluating the costs of abruptly switching between such different tasks. At the same time, the field of classifying oculomotor behavior has been moving toward more advanced, data-driven methods of decoding data. For the current study, we used a large dataset compiled over multiple experiments and implemented separate state-of-the-art machine learning methods for decoding both cognitive state and task-switching. We found that, by extracting a wide range of oculomotor features, we were able to implement robust classifier models for decoding both cognitive state and task-switching. Our decoding performance highlights the feasibility of this approach, even invariant of image statistics. Additionally, we present a feature ranking for both models, indicating the relative magnitude of different oculomotor features for both classifiers. These rankings indicate a separate set of important predictors for decoding each task, respectively. Finally, we discuss the implications of the current approach related to interpreting the decoding results.

The frontal cortex is heavily involved in oculomotor selection. Here, we investigated the neural correlates of eye movement selection during an antisaccade task in a young epileptic patient in whom the seizure focus included the frontal cortex and affected its function. Before resection surgery, the patient had difficulty in performing correct antisaccades towards the visual field contralateral to the seizure focus. Because the FEF is the only area in the human frontal cortex that is known to have a lateralized oculomotor function in the antisaccade task, this behavioural imbalance between the two visual fields suggests a disruption of FEF functioning by the nearby seizure focus. Electrocorticographic recordings at the seizure focus indeed showed that the seizure focus interfered with correct antisaccade performance. These results were in line with fMRI recordings revealing less task-related frontal activity for the hemisphere of the seizure focus, possibly reflecting diminished top-down engagement of the oculomotor system. Two months after removal of the compromised tissue, the seizures had disappeared, and antisaccade performance was the same for both visual hemifields. We conclude that a seizure focus in the frontal cortex can induce a dysfunction in the selection of eye movements, which is resolved after removal of interfering tissue., (© 2017 The British Psychological Society.)

The retinal location of visual information changes each time we move our eyes. Although it is now known that visual information is remapped in retinotopic coordinates across eye-movements (saccades), it is currently unclear how head-centered auditory information is remapped across saccades. Keeping track of the location of a sound source in retinotopic coordinates requires a rapid multi-modal reference frame transformation when making saccades. To reveal this reference frame transformation, we designed an experiment where participants attended an auditory or visual cue and executed a saccade. After the saccade had landed, an auditory or visual target could be presented either at the prior retinotopic location or at an uncued location. We observed that both auditory and visual targets presented at prior retinotopic locations were reacted to faster than targets at other locations. In a second experiment, we observed that spatial attention pointers obtained via audition are available in retinotopic coordinates immediately after an eye-movement is made. In a third experiment, we found evidence for an asymmetric cross-modal facilitation of information that is presented at the retinotopic location. In line with prior single cell recording studies, this study provides the first behavioral evidence for immediate auditory and cross-modal transsaccadic updating of spatial attention. These results indicate that our brain has efficient solutions for solving the challenges in localizing sensory input that arise in a dynamic context., Competing Interests: The authors have declared that no competing interests exist.

Attention and eye movements provide a window into the selective processing of visual information. Evidence suggests that selection is influenced by various factors and is not always under the strategic control of the observer. The aims of this tutorial review are to give a brief introduction to eye movements and attention and to outline the conditions that help determine control. Evidence suggests that the ability to establish control depends on the complexity of the display as well as the point in time at which selection occurs. Stimulus-driven selection is more probable in simple displays than in complex natural scenes, but it critically depends on the timing of the response: Salience determines selection only when responses are triggered quickly following display presentation, and plays no role in longer-latency responses. The time course of selection is also important for the relationship between attention and eye movements. Specifically, attention and eye movements appear to act independently when oculomotor selection is quick, whereas attentional processes are able to influence oculomotor control when saccades are triggered only later in time. This relationship may also be modulated by whether the eye movement is controlled in a voluntary or an involuntary manner. To conclude, we present evidence that shows that visual control is limited in flexibility and that the mechanisms of selection are constrained by context and time. The outcome of visual selection changes with the situational context, and knowing the constraints of control is necessary to understanding when and how visual selection is truly controlled by the observer.

During scene viewing, saccades directed toward a recently fixated location tend to be delayed relative to saccades in other directions ("delay effect"), an effect attributable to inhibition of return (IOR) and/or saccadic momentum (SM). Previous work indicates this effect may be task-specific, suggesting that gaze control parameters are task-relevant and potentially affected by task-switching. Accordingly, the present study investigated task-set control of gaze behavior using the delay effect as a measure of task performance. The delay effect was measured as the effect of relative saccade direction on preceding fixation duration. Participants were cued on each trial to perform either a search, memory, or rating task. Tasks were performed either in pure-task or mixed-task blocks. This design allowed separation of switch-cost and mixing-cost. The critical result was that expression of the delay effect at 2-back locations was reversed on switch versus repeat trials such that return was delayed in repeat trials but speeded in switch trials. This difference between repeat and switch trials suggests that gaze-relevant parameters may be represented and switched as part of a task-set. Existing and new tests for dissociating IOR and SM accounts of the delay effect converged on the conclusion that the delay at 2-back locations was due to SM, and that task-switching affects SM. Additionally, the new test simultaneously replicated noncorroborating results in the literature regarding facilitation-of-return (FOR), which confirmed its existence and showed that FOR is "reversed" SM that occurs when preceding and current saccades are both directed toward the 2-back location., ((c) 2015 APA, all rights reserved).)

Macular degeneration is the main cause for diminished visual acuity in the elderly. The juvenile form of macular degeneration has equally detrimental consequences on foveal vision. To compensate for loss of foveal vision most patients with macular degeneration adopt an eccentric preferred retinal location that takes over tasks normally performed by the healthy fovea. It is unclear however, whether the preferred retinal locus also develops properties typical for foveal vision. Here, we investigated whether the fixation characteristics of the preferred retinal locus resemble those of the healthy fovea. For this purpose, we used the fixation-offset paradigm and tracked eye-position using a high spatial and temporal resolution infrared eye-tracker. The fixation-offset paradigm measures release from fixation under different fixation conditions and has been shown useful to distinguish between foveal and non-foveal fixation. We measured eye-movements in nine healthy age-matched controls and five patients with juvenile macular degeneration. In addition, we performed a simulation with the same task in a group of five healthy controls. Our results show that the preferred retinal locus does not adopt a foveal type of fixation but instead drifts further away from its original fixation and has overall increased fixation instability. Furthermore, the fixation instability is most pronounced in low frequency eye-movements representing a slow drift from fixation. We argue that the increased fixation instability cannot be attributed to fixation under an unnatural angle. Instead, diminished visual acuity in the periphery causes reduced oculomotor control and results in increased fixation instability.

Recent research on grapheme-colour synesthesia has focused on whether visual attention is necessary to induce a synesthetic percept. The current study investigated the influence of synesthesia on overt visual attention during an oculomotor target selection task. Chromatic and achromatic stimuli were presented with one target among distractors (e.g. a '2' (target) among multiple '5's (distractors)). Participants executed an eye movement to the target. Synesthetes and controls showed a comparable target selection performance across conditions and a 'pop-out effect' was only seen in the chromatic condition. As a pop-out effect was absent for the synesthetes in the achromatic condition, a synesthetic element appears not to elicit a synesthetic colour, even when it is the target. The synesthetic percepts are not pre-attentively available to distinguish the synesthetic target from synesthetic distractors when elements are presented in the periphery. Synesthesia appears to require full recognition to bind form and colour., (Copyright © 2011 Elsevier Inc. All rights reserved.)

We present a model of the eye movement system in which the programming of an eye movement is the result of the competitive integration of information in the superior colliculi (SC). This brain area receives input from occipital cortex, the frontal eye fields, and the dorsolateral prefrontal cortex, on the basis of which it computes the location of the next saccadic target. Two critical assumptions in the model are that cortical inputs are not only excitatory, but can also inhibit saccades to specific locations, and that the SC continue to influence the trajectory of a saccade while it is being executed. With these assumptions, we account for many neurophysiological and behavioral findings from eye movement research. Interactions within the saccade map are shown to account for effects of distractors on saccadic reaction time (SRT) and saccade trajectory, including the global effect and oculomotor capture. In addition, the model accounts for express saccades, the gap effect, saccadic reaction times for antisaccades, and recorded responses from neurons in the SC and frontal eye fields in these tasks.

Visual neglect has been associated with an imbalance in the level of activity in the saccadic system: activity in the contralesional field is suppressed, which makes target selection unlikely. We recorded eye movements of a patient with hemispatial neglect and a group of healthy participants during an oculomotor distractor paradigm. Results showed that the interfering effects of a distractor were very strong when presented in her ipsilesional visual field. However, when the distractor was presented in her contralesional field, there were no interfering effects when the target was presented in her ipsilesional field. These findings could not be explained by the presence of a visual field defect as revealed by the results of two hemianopic patients. Our results are in line with an imbalance in the level of activity in the saccadic system in visual neglect because visual elements presented in the contralesional field did not compete for saccadic selection.

The neural substrates of eye movement measures are largely known. Therefore, measurement of eye movements in psychiatric disorders may provide insight into the underlying neuropathology of these disorders. Visually guided saccades, antisaccades, memory guided saccades, and smooth pursuit eye movements will be reviewed in various childhood psychiatric disorders. The four aims of this review are (1) to give a thorough overview of eye movement studies in a wide array of psychiatric disorders occurring during childhood and adolescence (attention-deficit/hyperactivity disorder, oppositional deviant disorder and conduct disorder, autism spectrum disorders, reading disorder, childhood-onset schizophrenia, Tourette's syndrome, obsessive compulsive disorder, and anxiety and depression), (2) to discuss the specificity and overlap of eye movement findings across disorders and paradigms, (3) to discuss the developmental aspects of eye movement abnormalities in childhood and adolescence psychiatric disorders, and (4) to present suggestions for future research. In order to make this review of interest to a broad audience, attention will be given to the clinical manifestation of the disorders and the theoretical background of the eye movement paradigms.

There is evidence that some visual information in blind regions may still be processed in patients with hemifield defects after cerebral lesions ("blindsight"). We tested the hypothesis that, in the absence of retinogeniculostriate processing, residual retinotectal processing may still be detected as modifications of saccades to seen targets by irrelevant distractors in the blind hemifield. Six patients were presented with distractors in the blind and intact portions of their visual field and participants were instructed to make eye movements to targets in the intact field. Eye movements were recorded to determine if blind-field distractors caused deviation in saccadic trajectories. No deviation was found in one patient with an optic chiasm lesion, which affect both retinotectal and retinogeniculostriate pathways. In five patients with lesions of the optic radiations or the striate cortex, the results were mixed, with two of the five patients showing significant deviations of saccadic trajectory away from the "blind" distractor. In a second experiment, two of the five patients were tested with the target and the distractor more closely aligned. Both patients showed a "global effect," in that saccades deviated toward the distractor, but the effect was stronger in the patient who also showed significant trajectory deviation in the first experiment. Although our study confirms that distractor effects on saccadic trajectory can occur in patients with damage to the retinogeniculostriate visual pathway but preserved retinotectal projections, there remain questions regarding what additional factors are required for these effects to manifest themselves in a given patient.

The present study investigated the contribution of the presence of a visual signal at the saccade goal on saccade trajectory deviations and measured distractor-related inhibition as indicated by deviation away from an irrelevant distractor. Performance in a prosaccade task where a visual target was present at the saccade goal was compared to performance in an anti- and memory-guided saccade task. In the latter two tasks no visual signal is present at the location of the saccade goal. It was hypothesized that if saccade deviation can be ultimately explained in terms of relative activation levels between the saccade goal location and distractor locations, the absence of a visual stimulus at the goal location will increase the competition evoked by the distractor and affect saccade deviations. The results of Experiment 1 showed that saccade deviation away from a distractor varied significantly depending on whether a visual target was presented at the saccade goal or not: when no visual target was presented, saccade deviation away from a distractor was increased compared to when the visual target was present. The results of Experiments 2-4 showed that saccade deviation did not systematically change as a function of time since the offset of the target. Moreover, Experiments 3 and 4 revealed that the disappearance of the target immediately increased the effect of a distractor on saccade deviations, suggesting that activation at the target location decays very rapidly once the visual signal has disappeared from the display.

Previous research has shown that in order to make an accurate saccade to a target object, nearby distractor objects need to be inhibited. The extent to which saccade trajectories deviate away from a distractor is often considered to be an index of the strength of inhibition. The present study shows that the mere expectation that a distractor will appear at a specific location is enough to generate saccade deviations away from this location. This suggests that higher-order cognitive processes such as top-down expectancy interact with low-level structures involved in eye movement control. The results will be discussed in the light of current theories of target selection and possible neurophysiological correlates.

In the last two decades, research has shown that eye movement trajectories can be modified by situational determinants. These modifications can inform us about the mechanisms that control eye movements and they can yield information about the oculomotor, memory and attention system that is not easily obtained via other sources. Eye movement trajectories can deviate either towards or away from elements in the visual field. We review the conditions in which these deviations are found and the mechanisms underlying trajectory deviations. It is argued that deviations towards an element are caused by the unresolved competition in the oculomotor system between elements in a visual scene. Deviations away from an element are mainly observed in situations in which top-down preparation can influence the target selection process, but the exact cause of such deviations remains unclear.

Previous studies investigating the ability of high priority stimuli to grab attention reached contradictory outcomes. The present study used eye tracking to examine the effect of the presence of the self-face among other faces in a visual search task in which the face identity was task-irrelevant. We assessed whether the self-face (1) received prioritized selection (2) caused a difficulty to disengage attention, and (3) whether its status as target or distractor had a differential effect. We included another highly familiar face to control whether possible effects were self-face specific or could be explained by high familiarity. We found that the self-face interfered with the search task. This was not due to a prioritized processing but rather to a difficulty to disengage attention. Crucially, this effect seemed due to the self-face's familiarity, as similar results were obtained with the other familiar face, and was modulated by the status of the face since it was stronger for targets than for distractors. (Contains 5 figures.)

In the assessment of visual working memory, estimating the maximum capacity is currently the gold standard. However, traditional tasks disregard that information generally remains available in the external world. Only when to-be-used information is not readily accessible, memory is taxed. Otherwise, people sample information from the environment as a form of cognitive offloading. To investigate how memory deficits impact the trade-off between sampling externally or storing internally, we compared gaze behaviour of individuals with Korsakoff amnesia (n = 24, age range 47–74 years) and healthy controls (n = 27, age range 40–81 years) on a copy task that provoked different strategies by having information freely accessible (facilitating sampling) or introducing a gaze-contingent waiting time (provoking storing). Indeed, patients sampled more often and longer, compared to controls. When sampling became time-consuming, controls reduced sampling and memorised more. Patients also showed reduced and longer sampling in this condition, suggesting an attempt at memorisation. Importantly, however, patients sampled disproportionately more often than controls, whilst accuracy dropped. This finding suggests that amnesia patients sample frequently and do not fully compensate for increased sampling costs by memorising more at once. In other words, Korsakoff amnesia resulted in a heavy reliance on the world as 'external memory'. [ABSTRACT FROM AUTHOR]

Every time we move our eyes, the retinal locations of objects change. To distinguish the changes caused by eye movements from actual external motion of the objects, the visual system is thought to anticipate the consequences of eye movements (saccades). Single neuron recordings have indeed demonstrated changes in receptive fields before saccade onset. Although some EEG studies with human participants have also demonstrated a pre-saccadic increased potential over the hemisphere that will process a stimulus after a saccade, results have been mixed. Here, we used magnetoencephalography to investigate the timing and lateralization of visually evoked planar gradients before saccade onset. We modelled the gradients from trials with both a saccade and a stimulus as the linear combination of the gradients from two conditions with either only a saccade or only a stimulus. We reasoned that any residual gradients in the condition with both a saccade and a stimulus must be uniquely linked to visually-evoked neural activity before a saccade. We observed a widespread increase in residual planar gradients. Interestingly, this increase was bilateral, showing activity both contralateral and ipsilateral to the stimulus, i.e. over the hemisphere that would process the stimulus after saccade offset. This pattern of results is consistent with predictive pre-saccadic changes involving both the current and the future receptive fields involved in processing an attended object, well before the start of the eye movement. The active, sensorimotor coupling of vision and the oculomotor system may underlie the seamless subjective experience of stable and continuous perception. [ABSTRACT FROM AUTHOR]

Accessing the contents of visual short-term memory (VSTM) is compromised by information bottlenecks and visual interference between memorization and recall. Retro-cues, displayed after the offset of a memory stimulus and prior to the onset of a probe stimulus, indicate the test item and improve performance in VSTM tasks. It has been proposed that retro-cues aid recall by transferring information from a high-capacity memory store into visual working memory (multiple-store hypothesis). Alternatively, retro-cues could aid recall by redistributing memory resources within the same (low-capacity) working memory store (single-store hypothesis). If retro-cues provide access to a memory store with a capacity exceeding the set size, then, given sufficient training in the use of the retro-cue, near-ceiling performance should be observed. To test this prediction, 10 observers each performed 12 hours across 8 sessions in a retro-cue change-detection task (40,000+ trials total). The results provided clear support for the single-store hypothesis: retro-cue benefits (difference between a condition with and without retro-cues) emerged after a few hundred trials and then remained constant throughout the testing sessions, consistently improving performance by two items, rather than reaching ceiling performance. Surprisingly, we also observed a general increase in performance throughout the experiment in conditions with and without retro-cues, calling into question the generalizability of change-detection tasks in assessing working memory capacity as a stable trait of an observer (data and materials are available at osf.io/9xr82 and github.com/paulzerr/retrocues). In summary, the present findings suggest that retro-cues increase capacity estimates by redistributing memory resources across memoranda within a low-capacity working memory store. [ABSTRACT FROM AUTHOR]

Traditional models of visual memory rely solely on internal memory and ignore our reliance on the information that is physically present in the external visual world. Experiments on visual working memory generally use paradigms that are designed to maximally load internal memory storage, although these situations do not necessarily translate to the actual use of visual working memory in daily life. Here, I discuss an embodied view of visual memory in which there is a continuous decision about which information to internalize and which information to leave in the external world for (possible) access later in time. In this view, the known limited capacity of visual working memory is not a problem in daily life, as the external world typically remains readily available and can be accessed relatively easily by executing eye movements to relevant locations. [ABSTRACT FROM AUTHOR]

Understanding the development of attention is key to understanding cognitive maturation. The gap-overlap task can be administered at all ages and is widely used to study the development of overt visual attention. However, studies using the gap-overlap task report different measures and little is known about the tasks' psychometric properties, especially in infants. We tested the 1-week test-retest reliability of two frequently used gap-overlap measures of attentional disengagement in 10-month-old infants; the gap effect as measured by the difference between the gap and overlap condition and the gap effect as measured by the difference between the gap and baseline condition. Sixty-seven infants performed the gap-overlap task twice, of which 45 infants had sufficient data quality for further analyses. Test-retest reliability of the overlap-gap gap effect was higher ( r = .50) than the baseline-gap gap effect ( r = .29). Moreover, the shared variance between overlap and baseline saccadic reaction times was moderate to high across sessions. In light of these results and the methodological challenges and limitations of infant research, we consider the overlap-gap gap effect to be a good measure to study the development of attentional disengagement in infants and suggest the exclusion of the baseline condition in future studies. [ABSTRACT FROM AUTHOR]

Abstract: Five patients with lesions involving intra-parietal cortex (IPCx) were tested in a rapid version of the double step paradigm to investigate the role of the IPCx in the rapid, online, updating of a saccade program. Saccades were executed to a single target in either the contra- or the ipsilesional visual field. In two thirds of the trials, a step change in target position required that the saccade shifted to a new location within the same field but in the contra- or the ipsilesional direction, allowing us to investigate whether patients are able to update their saccade program given new exogenous information about the required endpoint of the saccade. This set-up resulted in three types of initial saccades: saccades to the target on no-step trials, uncorrected saccades to the original target location on step trials and corrected saccades to the new target location on step trials. Furthermore, if the updating of the original eye movement program failed, patients performed a second saccade to the new target location that required a rapid error correction. The analysis of the double-step task on a group level indicated that latencies for all trial types were longer when saccades were directed to the contralesional versus the ipsilesional field. Furthermore, longer latencies were required for patients to initiate a corrective second saccade after making an uncorrected first saccade in their contralesional compared to ipsilesional field. There were no differences in the ultimate landing positions of the eye movements for such corrected saccades. These results reveal that deficits in updating of saccade programs only seem to be present if the updating must occur after the gaze has shifted to a new location, pointing to a role of intra-parietal cortex in the processes involved in updating information when the current reference frame has to be updated. In conclusion, the paradigm deployed in the current study allows for a refinement of the role of the intra-parietal cortex in the updating of saccade programs. [Copyright &y& Elsevier]

Highlights: [•] Six patients with a lesion to the frontal oculomotor cortex performed a double stimulus paradigm. [•] Latencies to the contralesional visual field were longer when a task instruction was given. [•] This effect was strongest when strong oculomotor inhibition was applied. [•] FEF lesions result in a slowing of the inhibitory signals associated with the rejection of a distractor. [•] These results reveal the important role of the FEF in the voluntary control of eye movements. [ABSTRACT FROM AUTHOR]

The introduction of non-target objects into a workspace leads to temporal and spatial adjustments of reaching trajectories towards a target. If the non-target is obstructing the path of the hand towards the target, the reach is adjusted such that collision with the non-target, or obstacle, is avoided. Little is known about the influence of features which are irrelevant for the execution of the movement on avoidance movements, like color similarity between target and non-target objects. In eye movement studies the similarity of non-targets has been revealed to influence oculomotor competition. Because of the tight neural and behavioral coupling between the gaze and reaching system, our aim was to determine the contribution of similarity between target and non-target to avoidance movements. We performed 2 experiments in which participants had to reach to grasp a target object while a non-target was present in the workspace. These non-targets could be either similar or dissimilar in color to the target. The results indicate that the non-spatial feature similarity can further modify the avoidance response and therefore further modify the spatial path of the reach. Indeed, we find that dissimilar pairs have a stronger effect on reaching-to-grasp movements than similar pairs. This effect was most pronounced when the non-target was on the outside of the reaching hand, where it served as more of an obstacle to the trailing arm. We propose that the increased capture of attention by the dissimilar obstacle is responsible for the more robust avoidance response. [ABSTRACT FROM AUTHOR]

Abstract: In recent years, the number of studies that have used deviations of saccade trajectories as a measure has rapidly increased. This review discusses these recent studies and summarizes advances in this field. A division can be made into studies that have used saccade deviations to measure the amount of attention allocated in space and studies that have measured the strength of the activity of a distractor. Saccade deviations have also been used to measure target selection in special populations. Most importantly, recent studies have revealed novel knowledge concerning the spatial tuning and temporal dynamics of target selection in the oculomotor system. Deviations in saccade trajectories have shown to constitute a valuable measure of various processes that control and influence our behavior which can be applied to multiple domains. [Copyright &y& Elsevier]

Abstract: The present study investigated whether subliminal (unconsciously perceived) visual information influences eye movement metrics, like saccade trajectories and endpoints. Participants made eye movements upwards and downwards while a subliminal distractor was presented in the periphery. Results showed that the subliminal distractor interfered with the execution of an eye movement, although the effects were smaller compared to a control experiment in which the distractor was presented supraliminal. Because saccade metrics are mediated by low level brain areas, this indicates that subliminal visual information evokes competition at a very low level in the oculomotor system. [Copyright &y& Elsevier]

Abstract: This study used a classic exogenous cueing task in which an abrupt onset cue indicated the target location at chance level. When there was a delay between the cue and the target, observers responded slower and less accurate to the target presented at cued than at uncued locations, signifying the occurrence of inhibition-of-return (IOR). On some trials, instead of a manual response, participants had to move their eyes to a location in space. Our findings show no saccade deviation away from the location that was inhibited due to IOR unless participants had to process the target letter presented at the inhibited location. Our findings are consistent with the notion that inhibition resulting in IOR does not occur at the saccade map level but IOR seems to reduce the input of signals going into the saccade map. We show that the strength of saccade deviation is an important measure which can reveal the amount of attentional processing taking place at any particular location in time. [Copyright &y& Elsevier]

Abstract: We tested a recent hypothesis suggesting that the eye deviates away from a location when top-down preparation can influence target selection. Participants had to make an eye movement to a peripheral target. Before the upcoming target, a central cue indicated the likely target location. Results show that when the target was presented at a location different from that indicated by the cue, eye movements to the target deviated away from the cued location. Because central cues are under top-down control, the present results are in line with a determining role of top-down preparation on saccade direction. These results contrast with the findings reported in a similar paradigm executed with hand movements, in which the movements were mostly initiated in the direction of the cued location. Therefore, we conclude that inhibitory effects typically observed when executing eye movements may not be observed when executing hand movements in similar conditions. [Copyright &y& Elsevier]

Abstract: It is generally agreed that saccade deviations away from a distractor location represent inhibition in the oculomotor system. By systematically manipulating the location of a distractor we tested whether the inhibition of the distractor is coded coarsely or fine-grained. Results showed that the location of a distractor had an effect on the saccade trajectories, suggesting that the amount of inhibition observed depends on the location of the distractor. More specifically, the vertical distance of the distractor from fixation seems to be a determining factor. These findings have important implications for models that account for inhibition in the target selection process and the areas that could underlie inhibitory influences on the superior colliculus (SC), like the frontal eye fields (FEF) and the dorsolateral prefrontal cortex (dlPFC). Finally, the initial direction and the endpoint of a saccade were found to be strongly correlated, which contradicts recent models proposing that the initial saccade direction and saccade endpoint are unrelated. [Copyright &y& Elsevier]

Abstract: The present study uses event-related potentials (ERPs) to investigate the neurophysiological correlates of the mechanisms involved in selection of locations for saccades. Participants performed a task in which both target and distractor locations were cued on a trial-by-trial basis. Participants were instructed to make an eye movement to the cued target location and to ignore elements at the distractor location. This experimental set-up allowed the investigation of the mechanisms involved in the top-down preparation and inhibition of locations for an eye movement. When comparing responses to leftward and rightward pointing cues, we observed an early directing attention negativity (EDAN) and an anterior directing attention negativity (ADAN) effect in the cue–target interval. These effects were similar to those observed in studies investigating attentional allocation, suggesting a close link between shifts of spatial attention and the preparation of eye movements. These components were followed by a late widespread contralateral negativity (LDAN) that was assumed to reflect both the oculomotor programming of the upcoming eye movement as well as attentional orienting. Furthermore, a new component was observed related to top-down inhibition of the distractor location. In response to the distractor cue, an early positivity above the right hemisphere (RLIP) was revealed. Finally, no modulations of early target-evoked ERP components were observed, suggesting that these components are unaffected when no further processing is required at the cued location. [Copyright &y& Elsevier]

Abstract: This study shows that the exact spatial location of a distractor can have a modulatory influence on saccade trajectories. Distractors close to the target evoke saccade trajectories that are directed towards the distractor, while distractors close to fixation result in saccades that are directed away from the distractor. This finding questions the idea that target positions are coarsely coded in the superior colliculus. [Copyright &y& Elsevier]

Abstract: The present paper reports results of a dual task study in which two locations were endogenously cued as possible target locations, while only one eye movement had to be executed. During the cue period, letters were briefly presented at the saccade goals and at no-saccade goals. Results show that performance was better for letters presented at any of the saccade goals than for letters presented at the no-saccade locations. Furthermore saccades deviated away from the non-saccaded target location, suggesting inhibition of the location to which the eyes should not go. The results indicate that the premotor theory also holds for conditions in which attention is allocated to multiple locations. [Copyright &y& Elsevier]

• The size of the global effect zone (averaging zone) adapts to object features. • The averaging zone becomes larger for higher relative luminance contrast. • The averaging zone becomes larger for faster saccadic response times. When two peripheral objects are presented in close proximity, saccades towards one of these objects land at a weighted average location between the two objects. This phenomenon, known as the 'global effect' or 'saccade averaging', disappears when the distance between the objects increases. When objects are further apart, outside the averaging zone, saccades land on one of the objects with little or no saccade averaging. Although it is known that the strength of the global effect is dependent on the specific features of the two objects, it is unclear if the size of the zone in which averaging can occur (i.e., the averaging zone) is adaptive. The aim of the current study was to investigate whether the size of the averaging zone adapts to variations in object luminance contrast of the objects. In order to systematically assess changes in the averaging zone, in two experiments, observers made saccadic eye movements while the luminance of the target and the distractor varied. We report three major findings: 1) When a distractor was more luminant relative to the target, the averaging zone increased (Exp. 1). Notably, saccade averaging never entirely ceased to exist, even for remote distractors. 2) When target and distractor were equiluminant, the averaging zone did not change with absolute luminance (Exp. 2). 3) Higher (relative and absolute) luminance increased the averaging zone especially for shorter saccadic response times (SRT). We conclude that the averaging zone is adaptive and becomes larger with increasing relative luminance and especially when SRTs are short. [ABSTRACT FROM AUTHOR]

Sensitive periods have previously been identified for several human visual system functions, such as global motion perception and face perception. Goal directed eye movements are crucial for efficient visual perception. Non-human primates and cats which had been visually deprived from birth have previously been shown to recover some oculomotor control following visual experience. The present study investigated whether sensitive periods exist in the development of human oculomotor control. Eye movements in individuals born with total bilateral cataracts were, at least one year after sight-restoration, compared to the eye movements of sight-restored late blind individuals, individuals with strong pathological nystagmus and controls with typical vision. Congenital cataract reversal individuals regained the ability to make systematic, purposeful gaze shifts, even after decades of blindness. The typical strong nystagmus of congenital cataract reversal individuals caused distorted eye movement trajectories, but measures of latency and accuracy were as expected from their prevailing nystagmus, that is, not worse than in individuals with a pathological nystagmus due to other reasons than a period of blindness. By contrast, saccade velocity was lower in congenital cataract reversal individuals than in any of the control groups. This first study on basic characteristics of oculomotor control in cataract reversal individuals has demonstrated a remarkable recovery of goal directed gaze shifts despite some remaining impairments in oculomotor control. Thus, the more severe visual impairments observed in this group for higher visual functions cannot be fully explained by a lack of basic goal directed eye movements. [ABSTRACT FROM AUTHOR]

Subjectively, we experience a stable representation of the outside world across saccades. Although previous studies have reported that presaccadically acquired visual information influences postsaccadic perception, whether such information's priority to access visual awareness is either reset by each saccade or continuous across saccades remains unclear. To investigate this issue, we combined a breaking continuous flash suppression (b-CFS) with a saccade task. Before each saccade, a grating was presented in the peripheral visual field under suppression. After the saccade, the same grating was again presented under suppression at either the retinotopically matched, the spatiotopically matched, or a control location. By measuring the duration of the grating to break through CFS into awareness after a saccade, we could compare the breakthrough times across stimuli presented at the different locations. No difference in the reaction times between the spatiotopic and control location was observed, indicating that a saccade resets the buildup of an object's priority to access visual awareness. However, a longer breakthrough time was observed for the retinotopic as compared to the control location, suggesting that a form of retinotopic adaptation to the grating suppressed the priority to access visual awareness after a saccade. [ABSTRACT FROM AUTHOR]