Multiple Eye Movements Research Articles

Distraction and visual search characteristics of young drivers when using navigation system displays

Navigation systems are fast and efficient sources of road information for drivers. However, they can increase the potential for accidents by distracting drivers. This study investigated the impact of navigation systems on driver distraction and visual search under various driving conditions. Using a driving simulator, eye-tracking technology recorded visual search data from twenty young drivers. The experiment analyzed factors such as driving environment (urban and rural), illumination level (day and night), and navigation system display size (large and small), as well as their interactions. Multiple eye movement metrics were employed, including duration and frequency of GPS fixation, dwell duration on the road ahead, and dwelling on mirrors and side windows. Statistical analysis employed repeated measures ANOVA to analyze the data. Findings revealed that small GPS displays caused greater distraction in terms of average and total gaze duration. Additionally, distraction increased during daytime driving conditions. In terms of visual search, wider and more dispersed search patterns were observed during the day, resulting in improved driving performance. This study aims to compare small and large navigation displays to identify the more effective option in reducing driver distractions. The research contributes to understanding driver distraction and visual search when using navigation system displays.

Research on drivers’ eye movement characteristics in the combined section of longitudinal slope and curve in the extra-long underwater tunnel

To explore the effects of a longitudinal slope, a curve, and their combined action on the eye movement characteristics and driving safety of drivers in extra-long underwater tunnel, vehicle tests are conducted. Their purpose is to obtain data on the pupil area change rate, blink duration, fixation duration, and average saccade time when a driver passes through each longitudinal slope and curve combination section. The change laws of‘ the eye movement characteristics in different curves and longitudinal slopes are analyzed. Moreover, the change models of the pupil area change rate, blink duration, fixation duration, and average saccade time of drivers under the combined action of a longitudinal slope and a curve are established. Considering multiple eye movement characteristics comprehensively, the TOPSIS method is used to analyze the drivers’ visual load of different longitudinal slope and curve combination sections. The results show that the interaction between a longitudinal slope and a curve has a significant impact on the eye movement characteristics of the drivers, with their combined effect being greater than that of a single factor, i.e., longitudinal slope or curve. A large longitudinal slope and a small curve radius imply a high pupil area change rate, long fixation duration, short blink duration, short average saccade time, and high visual load.

Eye fatigue assessment method for naked eye 3D display based on multiple eye movements

Eye fatigue assessment method for naked eye 3D display based on multiple eye movements

WildLab: A naturalistic free viewing experiment reveals previously unknown electroencephalography signatures of face processing.

Neural mechanisms of face perception are predominantly studied in well-controlled experimental settings that involve random stimulus sequences and fixed eye positions. Although powerful, the employed paradigms are far from what constitutes natural vision. Here, we demonstrate the feasibility of ecologically more valid experimental paradigms using natural viewing behaviour, by combining a free viewing paradigm on natural scenes, free of photographer bias, with advanced data processing techniques that correct for overlap effects and co-varying non-linear dependencies of multiple eye movement parameters. We validate this approach by replicating classic N170 effects in neural responses, triggered by fixation onsets (fixation event-related potentials [fERPs]). Importantly, besides finding a strong correlation between both experiments, our more natural stimulus paradigm yielded smaller variability between subjects than the classic setup. Moving beyond classic temporal and spatial effect locations, our experiment furthermore revealed previously unknown signatures of face processing: This includes category-specific modulation of the event-related potential (ERP)'s amplitude even before fixation onset, as well as adaptation effects across subsequent fixations depending on their history.

ABC of Gaze and Ocular Oscillations.

The chief goal of all eye movements is to maintain the image of an object steady on the retina especially the macula to preserve visual acuity. Gaze palsy refers to lack of the conjugate movements due to a failure of supranuclear control mechanisms. Supranuclear control is maintained by not one, but multiple eye movement systems and gaze mechanisms. Supranuclear gaze palsies can be associated with a myriad of aetiologies- from trauma or metabolic abnormalities to stroke, demyelinating disorders and space occupying lesions like tumours. Culprit lesions may be in frontal motor centres, brainstem gaze centres gaze or interconnecting segments. While the brainstem network for horizontal gaze lies in pons, that for vertical gaze is situated in midbrain. Further, ocular oscillations and nystagmus are abnormal eye movements that disrupt a steady fixation of gaze. It is prudent to be aware of various gaze pathways and their anatomical corelates in order to establish a topographic relationship of clinical findings. A systematic clinical examination may provide deep insights on the patho-physiological mechanisms along with aiding in localizing the lesion accurately. This review deals with systematic clinical approach to various gaze control systems.

The effect of subliminal incentives on goal-directed eye movements.

Over the last decades, several studies have demonstrated that conscious and unconscious reward incentives both affect performance in physical and cognitive tasks, suggesting that goal pursuit can arise from an unconscious will. Whether the planning of goal-directed saccadic eye movements during an effortful task can also be affected by subliminal reward cues has not been systematically investigated. We employed a novel task where participants made several eye movements back and forth between a fixation point and a number of peripheral targets. The total number of targets visited by the eyes in a fixed amount of time determined participants' monetary gain. The magnitude of the reward at stake was briefly shown at the beginning of each trial and masked by pattern images superimposed in time so that at shorter display durations participants perceived reward incentives subliminally. We found a main effect of reward across all display durations as higher reward enhanced participants' oculomotor effort measured as the frequency and peak velocity of saccades. This effect was strongest for consciously perceived rewards but also occurred when rewards were subliminally perceived. Although we did not find a statistically significant dissociation between the reward-related modulation of different saccadic parameters, across two experiments the most robust effect of subliminal rewards was observed for the modulation of the saccadic frequency but not the peak velocity. These results suggest that multiple indices of oculomotor effort can be incentivized by subliminal rewards and that saccadic frequency may provide the most sensitive indicator of subliminal incentivization of eye movements. NEW & NOTEWORTHY Reward incentives motivate humans to exert more effort, and they do so even when rewards are subconsciously perceived. It has been unknown whether these effects also extend to eye movements that have lower energetic demands compared with other movement types. We devised a behavioral task that required fast execution of multiple eye movements. Subliminal rewards enhanced the frequency and peak velocity of saccadic eye movements, with the most reliable effect observed for saccadic frequency.

Eye movement performance and clinical outcomes among female athletes post-concussion

ABSTRACT Background Most post-concussion eye movement (EM) research involves predominantly male samples. We evaluated pro- (PRO; reflexive shift of visual attention to target) and anti- (ANTI; executive control of visual attention away from target) computer-based saccade task performance among female, collegiate athletes with recent concussion (CON) versus healthy-control athletes (HC). We evaluated the relationship between EM performance and post-concussion outcomes. We hypothesized ANTI performance would differ among CON and HC due to greater executive control demands, and that EM performance (both tasks) would be associated with clinical outcomes in CON. Methods 16 CON (assessed 4–10 days post-injury [M = 6.87, SD = 2.15 days]) and 16 age-matched HC athletes were recruited. General linear mixed modeling and Pearson’s correlations were used. Results On ANTI, CON demonstrated higher error rate [F(1,2863) = 12.650, p<.001] and shorter latency on error trials [F(1,469) = 5.976, p=.015] relative to HC. Multiple EM measures were associated with clinical outcomes: PRO duration predicted days to symptom remission (r=.44, p <.05); ANTI error rate was associated with symptom burden on the day of testing (r=.27, p <.05). Conclusion This study demonstrates promising utility of EM measures to detect cognitive control and sensorimotor effects of concussion among female athletes and their use as a prognostic indicators of recovery.

Automatic processing of gaze movements to quantify gaze scanning behaviors in a driving simulator.

Eye and head movements are used to scan the environment when driving. In particular, when approaching an intersection, large gaze scans to the left and right, comprising head and multiple eye movements, are made. We detail an algorithm called the gaze scan algorithm that automatically quantifies the magnitude, duration, and composition of such large lateral gaze scans. The algorithm works by first detecting lateral saccades, then merging these lateral saccades into gaze scans, with the start and end points of each gaze scan marked in time and eccentricity. We evaluated the algorithm by comparing gaze scans generated by the algorithm to manually marked "consensus ground truth" gaze scans taken from gaze data collected in a high-fidelity driving simulator. We found that the gaze scan algorithm successfully marked 96% of gaze scans and produced magnitudes and durations close to ground truth. Furthermore, the differences between the algorithm and ground truth were similar to the differences found between expert coders. Therefore, the algorithm may be used in lieu of manual marking of gaze data, significantly accelerating the time-consuming marking of gaze movement data in driving simulator studies. The algorithm also complements existing eye tracking and mobility research by quantifying the number, direction, magnitude, and timing of gaze scans and can be used to better understand how individuals scan their environment.

Numerical control press design based on quantitative evaluation of appearance area features

The appearance characteristics of numerical control presses were quantitatively evaluated using eye-tracking technology, and a numerical control press design method was proposed to provide guidance for the design of such mechanical products. By investigating and analyzing the appearance of numerical control presses locally and abroad, the modeling characteristics of these products are summarized. The interest areas of the press are divided using the hot zone map data of the eye movement experiment, and people’s knowledge of each area of the press is quantitatively analyzed. Data generated by multiple eye movement experiments are combined with a subjective questionnaire to identify the mechanics of the press. The front and work areas are the main features of the press design. Based on the experiment result, the press design is conducted based on color and modeling elements. We used the Jiangsu CPTEK numerical control press as the actual case. We also re-matched the color, optimized the details, and developed an improved design scheme, thus verifying the proposed design method.

Effects of auditory feedback on movements with two-segment sequence and eye-hand coordination: Using a short auditory contact cue

During sequential reaches to multiple targets, eye and hand movements are highly coordinated, and the gaze is anchored to each target until the reaching hand makes contact to each of them. Such contact events are monitored by multimodal (visual, proprioceptive) sensory systems, and one function of the gaze anchoring to each target is verification of successful target contact (reach completion). The present study focused on this verification function and examined how planning and control of eye and hand movements during two-segment eye-hand movements are affected by augmented auditory feedback of reach completion. Young adults made a reach to the first target with a saccade, and then made another saccade to the second target in blocked trials. An auditory target-contact cue condition delivered four short sounds during the initial reach, and the last sound was synchronized with target contact, whereas a control condition lacked the last target-contact sound. The results showed that saccadic reaction time increased with the target-contact cue, especially when the reaching accuracy demand was high. The reach also became slower with lower peak velocity and longer time to peak velocity with that cue, suggesting that the limb-motor system lower the preplanned speed of the reach in a top-down fashion for a better preparation toward reach completion. However, no auditory effects were found for the timing of gaze shift to the second target. These results were different from those seen in previous studies, indicating that the effects of the additional auditory contact feedback differ depending on behavioral tasks and cue characteristics.

The role of fixation disengagement in the parallel programming of sequences of saccades

One of the core mechanisms involved in the control of saccade responses to selected target stimuli is the disengagement from the current fixation location, so that the next saccade can be executed. To carry out everyday visual tasks, we make multiple eye movements that can be programmed in parallel. However, the role of disengagement in the parallel programming of saccades has not been examined. It is well established that the need for disengagement slows down saccadic response time. This may be important in allowing the system to program accurate eye movements and have a role to play in the control of multiple eye movements but as yet this remains untested. Here, we report two experiments that seek to examine whether fixation disengagement reduces saccade latencies when the task completion demands multiple saccade responses. A saccade contingent paradigm was employed and participants were asked to execute saccadic eye movements to a series of seven targets while manipulating when these targets were shown. This both promotes fixation disengagement and controls the extent that parallel programming can occur. We found that trial duration decreased as more targets were made available prior to fixation: this was a result both of a reduction in the number of saccades being executed and in their saccade latencies. This supports the view that even when fixation disengagement is not required, parallel programming of multiple sequential saccadic eye movements is still present. By comparison with previous published data, we demonstrate a substantial speeded of response times in these condition (“a gap effect”) and that parallel programming is attenuated in these conditions.

Left-handers know what's left is right: Handedness and object affordance.

We live in a right-hander’s world. Although left-handers become accustomed to using right-handed devices, an underlying preference for objects that afford the dominant hand could remain. We employed eye tracking while left- and right-handed participants viewed advertisements for everyday products. Participants then rated aesthetic appeal, purchase intention, and perceived value. Left-handed participants found advertisements for products that more easily afforded them action to be more aesthetically appealing. They also indicated greater future purchase intention for products that were oriented towards the left hand, and gave these products a higher perceived value. Eye tracking data showed that object handles attracted attention, and were also able to retain participants’ attention. Further, across multiple eye movement measures, our data show that participant eye movements were altered by the orientation of the handle, such that this side of the image was examined earlier and for longer, regardless of handedness. Left-handers’ preferences might be stronger because they are more aware of object orientation, whereas right-handers do not experience the same difficulties. These findings highlight intrinsic differences in the way in which we perceive objects and our underlying judgments about those products, based on handedness.

No direction specific costs in trans-saccadic memory

Even though we frequently execute saccades, we perceive the external world as coherent and stable. An important mechanism of trans-saccadic perception is spatial remapping: the process of updating information across eye movements. Previous studies have indicated a right hemispheric dominance for spatial remapping, which has been proposed to translate into enhanced trans-saccadic memory for locations that are remapped into the right compared to the left hemisphere in healthy participants. Previous study designs suffered from several limitations, however (i.e. multiple eye movements had to be made instead of one, fixations were not controlled for, and ceiling effects were likely present). We therefore compared accuracy of trans-saccadic memory for central items after left- versus rightward eye movements, and secondary, for items that were remapped within the left versus right visual field. Participants memorized the location of a briefly presented item, made one saccade, and subsequently decided in what direction the item had shifted. We used a staircase to adjust task difficulty. Bayesian repeated measures ANOVAs were used to compare between left versus right eye movements and items in the left versus right visual field. We found most evidence against directional differences in trans-saccadic memory (BF10 = 0.23). We found some evidence suggestive of enhanced trans-saccadic memory for items that were remapped within the left compared to the right visual field (BF10 = 4.00). The latter result could be explained by a leftward spatial attention bias. As such, the hypothesized right hemispheric dominance for spatial remapping does not result in asymmetric trans-saccadic memory capacities in healthy participants.

Suppression of frontal eye field neuronal responses with maintained fixation

The decision of where to make an eye movement is thought to be driven primarily by responses to stimuli in neurons' receptive fields (RFs) in oculomotor areas, including the frontal eye field (FEF) of prefrontal cortex. It is also thought that a saccade may be generated when the accumulation of this activity in favor of one location or another reaches a threshold. However, in the reading and scene perception fields, it is well known that the properties of the stimulus at the fovea often affect when the eyes leave that stimulus. We propose that if FEF plays a role in generating eye movements, then the identity of the stimulus at fixation should affect the FEF responses so as to reduce the probability of making a saccade when fixating an item of interest. Using a visual foraging task in which animals could make multiple eye movements within a single trial, we found that responses were strongly modulated by the identity of the stimulus at the fovea. Specifically, responses to the stimulus in the RF were suppressed when the animal maintained fixation for longer durations on a stimulus that could be associated with a reward. We suggest that this suppression, which was predicted by models of eye movement behavior, could be a mechanism by which FEF can modulate the temporal flow of saccades based on the importance of the stimulus at the fovea.

Optimizing MSLT Specificity in Narcolepsy With Cataplexy.

Multiple sleep onset rapid eye movement (R) periods (SOREMPs) and a mean sleep latency of ≤8 minutes on the multiple sleep latency test (MSLT) are diagnostic criteria of narcolepsy (NC), but also occur in other conditions with increased sleep pressure, including insufficient sleep syndrome (ISS), sleep-disordered breathing (SDB), or Parkinson's disease (PD). These false positives are common, may create diagnostic uncertainty, and highlight the need for complementary MSLT measures with high specificity for NC. Detailed analysis of MSLT findings in 56 NC, 83 PD, 89 SDB, and 23 ISS patients, using receiver operating characteristic curves. A positive MSLT (mean sleep latency ≤ 8.0 minutes and ≥2 SOREMPs) was found in 53 NC (95%), 1 PD (1%), 8 SDB (9%), and 12 ISS patients (52%). MSLT-based differentiation between NC and non-NC patients was best when applying a mean R latency of ≤5 minutes (sensitivity/specificity/positive predictive value [PPV]: 49%/95%/96%) or a mean percentage of sleep stage R ≥ 40% (sensitivity/specificity/PPV: 60%/100%/100%) as cutoffs. When analyzing all 252 naps with SOREMPs in isolation, the combination of both R latency of ≤5 minutes and R percentage of ≥50% yielded a sensitivity/specificity/PPV of 50%/99%/99%. In addition, a sleep stage sequence with R occurring prior to N2 was more common in NC than in non-NC (71% vs. 32%, p < .001), and in combination with R percentage of ≥50% yielded a sensitivity/specificity/PPV of 53%/96%/97%. A better characterization of R sleep by latency, duration, and sleep stage sequence facilitates detection of false positives and, hence, contributes to a higher MSLT specificity in NC.

SacLab: A toolbox for saccade analysis to increase usability of eye tracking systems in clinical ophthalmology practice

PurposeMany open source software packages have been recently developed to expand the usability of eye tracking systems to study oculomotor behavior, but none of these is specifically designed to encompass all the main functions required for creating eye tracking tests and for providing the automatic analysis of saccadic eye movements. The aim of this study is to introduce SacLab, an intuitive, freely-available MATLAB toolbox based on Graphical User Interfaces (GUIs) that we have developed to increase the usability of the ViewPoint EyeTracker (Arrington Research, Scottsdale, AZ, USA) in clinical ophthalmology practice. MethodsSacLab consists of four processing modules that enable the user to easily create visual stimuli tests (Test Designer), record saccadic eye movements (Data Recorder), analyze the recorded data to automatically extract saccadic parameters of clinical interest (Data Analyzer) and provide an aggregate analysis from multiple eye movements recordings (Saccade Analyzer), without requiring any programming effort by the user. ResultsA demo application of SacLab to carry out eye tracking tests for the analysis of horizontal saccades was reported. We tested the usability of SacLab toolbox with three ophthalmologists who had no programming experience; the ophthalmologists were briefly trained in the use of SacLab GUIs and were asked to perform the demo application. The toolbox gained an enthusiastic feedback from all the clinicians in terms of intuitiveness, ease of use and flexibility. Test creation and data processing were accomplished in 52±21s and 46±19s, respectively, using the SacLab GUIs. ConclusionsSacLab may represent a useful tool to ease the application of the ViewPoint EyeTracker system in clinical routine in ophthalmology.

Classification of artifactual EEG signal and detection of multiple eye movement artifact zones using novel Time-amplitude algorithm

Electroencephalogram (EEG) signal has numerous applications in the field of medical science. It is used to diagnose many of the abnormalities, disorders, and diseases related to the human brain. The EEG signal contaminated with ocular artifacts makes it very difficult for analysis and diagnosis. This paper includes work on classification of artifactual/non-artifactual EEG time series and perfect detection of eye movement (EM) artifact contaminated EEG signal along with multiple EM artifactual zones in the same time series. Artificial Neural Network classifier in a simple perceptron model without hidden layer is used for the identification. This study presents a newly developed, simple, robust, and computationally fast statistical Time-Amplitude algorithm. By the application of novel Time-Amplitude algorithm on identified signal, the EM artifactual EEG signal along with multiple zones is automatically detected and marked accurately. Such robust, efficient, real-time and simple algorithm is not ever designed and used for ocular artifact detection by any author. The ROC analysis gives accuracy of the ANN model for classifying the presence of artifacts in the EEG data, which is 97.50 %. The time elapsed for executing the Time-Amplitude algorithm for automatic detection of EM artifact is very less (4.30 msec.) compared to DWT with Haar. It has the capability to detect multiple EM artifactual zones, in the same time, for the montage of 8-second EEG.

Mapping the macaque superior temporal sulcus: functional delineation of vergence and version eye-movement-related activity.

It is currently thought that the primate oculomotor system has evolved distinct but interrelated subsystems to generate different types of visually guided eye movements (e.g., saccades/smooth pursuit/vergence). Although progress has been made in elucidating the neural basis of these movement types, no study to date has investigated all three movement types on a large scale and within the same animals. Here, we used fMRI in rhesus macaque monkeys to map the superior temporal sulcus (STS) for BOLD modulation associated with visually guided eye movements. Further, we ascertained whether modulation in a given area was movement type specific and, if not, the modulation each movement type elicited relative to the others (i.e., dominance). Our results show that multiple areas within STS modulate during all movement types studied, including the middle temporal, medial superior temporal, fundus of the superior temporal, lower superior temporal, and dorsal posterior inferotemporal areas. Our results also reveal an area in dorsomedial STS that is modulated almost exclusively by vergence movements. In contrast, we found that ventrolateral STS is driven preferentially during versional movements. These results illuminate an STS network involved in processes associated with multiple eye movement types, illustrate unique patterns of modulation within said network as a function of movement type, and provide evidence for a vergence-specific area within dorsomedial STS. We conclude that producing categorically different eye movement types requires access to a common STS network and that individual network nodes are recruited differentially based upon the type of movement generated.

Contextual factors modulate concurrent planning of sequential saccades.

Natural vision typically involves making multiple eye movements to interpret complex visual scenes. Although previous work has shown that individual saccadic end points are modulated by cognitive context, whether and how contextual factors quantitatively influence the planning of sequential saccades is still unclear. We compared performance of subjects in a modified double-step task under different task instructions (FOLLOW vs. REDIRECT; Ray, Schall, & Murthy, 2004) as well as task structure (40% and 100% FOLLOW). The results support the idea of restricted concurrent preparation when the second saccade was part of the sequence as per task demands as opposed to being inadvertently made following an error. Also, increasing the probability of double-target trials in the task (100% vs. 40% FOLLOW) tended to enhance concurrent planning even when the serial order of saccades continued to remain important. Taken together, these data reveal how the concurrent planning of sequential saccades can be contextually regulated by means of task instruction and trial statistics.

Saccades Toward the Target Are Planned as Sequences Rather Than as Single Steps

To find a target during visual search, observers often need to make multiple eye movements, which results in a scan path. It is an open question whether the saccade destinations in scan paths are planned ahead. In the two experiments reported here, we investigated this question by focusing on the observer’s ability to deviate from potentially planned paths. In the first experiment, the stimulus configuration could change during the initial saccade. We found that the observer’s ability to deviate from potentially planned paths crucially depended on whether altered configurations could be processed with sufficient rapidity. In a follow-up experiment, we asked whether planned paths can include more than two saccade destinations. Investigating the influence of potentially planned paths on a secondary task demonstrated that planned paths can include at least three saccade destinations. Together, these experiments provide the first evidence of scan-path planning in visual search.