Eye Movement Parameters Research Articles

Novice and Expert Anesthesiologists' Eye-Tracking Metrics During Simulated Epidural Block: A Preliminary, Brief Observational Report.

IntroductionEye tracking is the process of measuring an individual’s eye movements to register their attentional behavior by using a device called an eye-tracker. Studies conducted using eye-tracking techniques have demonstrated a number of differences in eye movement parameters and patterns between experts and novices. The aim of this preliminary study was to evaluate if there are any differences in eye-tracking metrics between novice and expert anesthesiologists during the performance of an epidural block using an epidural simulator.MethodsSeven experts and seven novices who gave their consent to this preliminary study were asked to perform an epidural technique using an epidural simulator while wearing a pair of Tobii Pro glasses. Number of fixations, fixation duration, heat maps and scan-paths were examined by Tobii Pro Lab Software. Duration of the procedure was also recorded.ResultsThe observation of the attentional heat map and gaze plot showed different gaze dispersion between experts and novices. The mean total duration of fixations during needle insertion and advancement and catheter introduction was lower in experts than trainees (respectively, 0.18 vs 3.56 sec; P<0.05 and 0.73 vs 2.48 sec; P<0.05). The mean fixation count was greater in experts vs trainees (5 vs 2; P<0.05). The mean duration of the epidural procedure was 104.16 (41) (trainees) vs 65.3 (32.6) seconds (experts) (P<0.05). Expert anesthesiologists spent more time fixating a more specific target location (eg, the point of the epidural needle rather than the syringe’s barrel) whilst novices split their attention between tracking their tools and the target location.DiscussionEye tracking may have interesting implications for the creation of assessment programs, which distinguish skill level through the use of gaze behavior, and may be a promising tool for monitoring training progress towards the development of expertise.

Early Diagnosis of Mild Cognitive Impairment Based on Eye Movement Parameters in an Aging Chinese Population.

Background: The pathogenesis of dementia often starts several years prior to clinical onset during which the individual is asymptomatic. Existing strategies for the accurate diagnosis of early dementia are limited by high cost and the invasive nature of the procedures. Eye movement parameters associated with cognitive functions may be helpful in the early identification of dementia and in the development and evaluation of preventive and therapeutic strategies.Objective: We aimed to assess differences in eye movement parameters between healthy elderly individuals and patients with mild cognitive impairment (MCI). Furthermore, we examined the correlations between eye movement parameters with cognitive functions and specific hemispheric region and neural structures in individuals with MCI.Method: Eighty individuals with MCI without dementia (based on DSM-IV criteria) identified by community screening and 170 healthy controls were administered Chinese versions of MoCA and NTB, and a long (20 min) or short (5 min) version of a visual paired comparison (VPC) task. Two weeks later, 44 MCI patients and 107 healthy controls completed a retest of the VPC task, 44 MCI patients and 43 healthy controls among them administered a MRI. At the end of 1-year follow-up, a subset of 26 individuals with MCI and 57 healthy controls were administered the long version of VPC task and MoCA test again. Eye movement parameters and the relationship of eye movement parameters with cognitive functions and with changes in neural structures were compared between groups.Results: Patients with MCI were older, had less education, and had lower scores on cognitive tests than healthy controls. After adjustment for age and level of education, patients with MCI had lower novelty preference scores on the VPC than healthy controls. Using the logistic regression model, the amount of time that subjects focused on these novel images could predict MCI patients from normal elderly with an out of sample area under the receiver operator characteristic curve of 0.62. Furthermore, the cognition score of subjects whose novelty preference score was low decreased more remarkably in 1 year. For both the patient and control groups, VPC novelty preference was significantly correlated with verbal fluency and delayed and short-term memory function. Novelty preference score was also significantly correlated with the cortical thickness of several structures in the right hemisphere.Conclusion: Eye movement parameters are stable indicators to distinguish patients with MCI and cognitively normal subjects and are not affected by different testing versions and numbers. Additionally, the patients’ cognitive deficits and eye movement indices were correlated. Future longitudinal studies should further explore the clinical utility of eye movement parameters as early markers of MCI.

Speed and accuracy of saccades in patients with glaucoma evaluated using an eye tracking perimeter

BackgroundTo examine the speed and accuracy of saccadic eye movements during a novel eye tracking threshold visual field assessment and determine whether eye movement parameters may improve ability to detect glaucoma.MethodsA prospective study including both eyes of 31 patients with glaucoma and 23 controls. Standard automated perimetry (SAP) and eye tracking perimetry (saccadic vector optokinetic perimetry, SVOP) was performed. SVOP provided data on threshold sensitivity, saccade latency, and two measures of accuracy of saccades (direction bias and amplitude bias). The relationship between eye movement parameters and severity of glaucoma was examined and Receiver Operating Characteristic curves were used to assess ability to detect glaucoma.ResultsPatients with glaucoma had significantly slower saccades (602.9 ± 50.0 ms versus 578.3 ± 44.6 ms for controls, P = 0.009) and reduced saccade accuracy (direction bias = 7.4 ± 1.8 versus 6.5 ± 1.5 degrees, P = 0.006). There was a significant slowing of saccades and saccades became less accurate with worsening SAP sensitivity. Slower saccades were associated with increased odds of glaucoma; however, the AUC for saccade latency was only 0.635 compared to 0.914 for SVOP sensitivity.ConclusionPatients with glaucoma had significant differences in eye movements compared to healthy subjects, with a relationship between slower and less accurate eye movements and worse glaucoma severity. However, in a multivariable model, eye movement parameters were not of additional benefit in differentiating eyes with glaucoma from healthy controls.

Evaluation of eye movements and visual performance in patients with cataract

Eye movement is an essential component of visual perception. Eye movement disorders have been observed in many eye disease, and are thought to affect various visual performance in daily life. However, eye movement behaviors of the elderly with cataract are poorly understood, and the impact of cataract surgery on eye movements has not been investigated. In this study, we observed the eye movement behaviors in thirty patients with bilateral age-related cataract while performing three performance-based tasks (visual search, face recognition and reading). Eye movements were automatically recorded by an eye tracker during task performance. We found an overall improved visual performance postoperatively, presented as elevated percentage of correctly identified objects and faces, reduced search time and increased reading speed. Eye movement parameters were found significantly altered after cataract surgery. Fixation count, total fixation duration and total visit duration were markedly increased in the visual search task and face recognition task. The proportion of regressive saccades was obviously decreased in the reading task. These eye movement parameters were found to be correlated with the measures of visual performance. Our findings suggested a potential association between the eye movement disturbance and impaired visual performance, and provided a new insight on the potential usefulness of eye movement as an objective and valid tool to understand visual impairments caused by cataract, as well as evaluate practical outcomes of cataract surgery.

Using eye movements to detect visual field loss: a pragmatic assessment using simulated scotoma

Glaucoma is a leading cause of irreversible sight-loss and has been shown to affect natural eye-movements. These changes may provide a cheap and easy-to-obtain biomarker for improving disease detection. Here, we investigated whether these changes are large enough to be clinically useful. We used a gaze-contingent simulated visual field (VF) loss paradigm, in which participants experienced a variable magnitude of simulated VF loss based on longitudinal data from a real glaucoma patient (thereby controlling for other variables, such as age and general health). Fifty-five young participants with healthy vision were asked to view two short videos and three pictures, either with: (1) no VF loss, (2) moderate VF loss, or (3) advanced VF loss. Eye-movements were recorded using a remote eye tracker. Key eye-movement parameters were computed, including saccade amplitude, the spread of saccade endpoints (bivariate contour ellipse area), location of saccade landing positions, and similarity of fixations locations among participants (quantified using kernel density estimation). The simulated VF loss caused some statistically significant effects in the eye movement parameters. Yet, these effects were not capable of consistently identifying simulated VF loss, despite it being of a magnitude likely easily detectable by standard automated perimetry.

Learning Scan Paths of Eye Movement in Autism Spectrum Disorder.

Eye tracking studies have demonstrated deficits in attention in individuals with Autism Spectrum Disorder (ASD) for a range of different social attention-based tasks. Here we examined social attention skills in a large sample of ASD participants (n = 120), using eye tracking data from a social information processing task, and compared them with a typically developing (TD) group (n = 35). Assuming eye movement parameters are random variables generated by an underlying stochastic process, we modeled the fixation sequences of participants in ASD and TD groups with a Hidden Markov Model. The Regions of Interests (ROIs), modeled as hidden states, corresponded to the true ROIs with a prediction accuracy of >90% for each group. The transition between ROIs revealed bias towards a specific area in the scene in ASD group, which deviated from the TD group. Objective time-dynamic measures of gaze patterns can potentially serve as useful endpoints in ASD diagnosis. Clinical Trial Registration: NCT02299700.

The Comprehensive Evaluation Method of the Human Factors in the Flight Deck Based on the Physical and Behaviour Measurements

There is increasing concern about the design and evaluation of the human factors in the flight deck. The study was to propose a comprehensive evaluation method of the human factors in the flight deck, combing with multiple physiological signals. The proposed comprehensive evaluation method in the flight deck are composed with the evaluation of the operators’ cognition, operational performance, control activities and workload. The cardiovascular signal, eye movement and flight parameters were recorded during task to conduct the evaluation. An experiment about the evaluation of the display elements in the flight deck was conducted to verify the proposed comprehensive method of the human factors. The results revealed the validity of the proposed method, which can give a detailed description of the operator’s workload, operational performance and cognition during the flight task.

Following in Jakobson and Lévi-Strauss' footsteps: A neurocognitive poetics investigation of eye movements during the reading of Baudelaire's 'Les Chats'.

Following Jakobson and Levi-Strauss [1] famous analysis of Baudelaire’s poem ‘Les Chats’ (‘The Cats’), in the present study we investigated the reading of French poetry from a Neurocognitive Poetics perspective. Our study is exploratory and a first attempt in French, most previous work having been done in either German or English (e.g. [2] [3] [4] [5] [6]). We varied the presentation mode of the poem Les Chats (verse vs. prose form) and measured the eye movements of our readers to test the hypothesis of an interaction between presentation mode and reading behavior. We specifically focussed on rhyme scheme effects on standard eye movement parameters. Our results replicate those from previous English poetry studies in that there is a specific pattern in poetry reading with longer gaze durations and more rereading in the verse than in the prose format. Moreover, presentation mode also matters for making salient the rhyme scheme. This first study generates interesting hypotheses for further research applying quantitative narrative analysis to French poetry and developing the Neurocognitive Poetics Model of literary reading [NCPM; 2] into a cross-linguistic model of poetry reading.

Task-dependence in scene perception: Head unrestrained viewing using mobile eye-tracking.

Real-world scene perception is typically studied in the laboratory using static picture viewing with restrained head position. Consequently, the transfer of results obtained in this paradigm to real-word scenarios has been questioned. The advancement of mobile eye-trackers and the progress in image processing, however, permit a more natural experimental setup that, at the same time, maintains the high experimental control from the standard laboratory setting. We investigated eye movements while participants were standing in front of a projector screen and explored images under four specific task instructions. Eye movements were recorded with a mobile eye-tracking device and raw gaze data were transformed from head-centered into image-centered coordinates. We observed differences between tasks in temporal and spatial eye-movement parameters and found that the bias to fixate images near the center differed between tasks. Our results demonstrate that current mobile eye-tracking technology and a highly controlled design support the study of fine-scaled task dependencies in an experimental setting that permits more natural viewing behavior than the static picture viewing paradigm.

Difference in eye movements during gait analysis between professionals and trainees.

IntroductionObservational gait analysis is a widely used skill in physical therapy. Meanwhile, the skill has not been investigated using objective assessments. The present study investigated the differences in eye movement between professionals and trainees, while observing gait analysis.MethodsThe participants included in this study were 26 professional physical therapists and 26 physical therapist trainees. The participants, wearing eye tracker systems, were asked to describe gait abnormalities of a patient as much as possible. The eye movement parameters of interest were fixation count, average fixation duration, and total fixation duration.ResultsThe number of gait abnormalities described was significantly higher in professionals than in trainees, overall and in limbs of the patient. The fixation count was significantly higher in professionals when compared to trainees. Additionally, the average fixation duration and total fixation duration were significantly shorter in professionals. Conversely, in trunks, the number of gait abnormalities and eye movements showed no significant differences between groups.ConclusionsProfessionals require shorter fixation durations on areas of interest than trainees, while describing a higher number of gait abnormalities.

An Extended Method for Saccadic Eye Movement Measurements Using a Head-Mounted Display.

Saccadic eye movement is an important ability in our daily life and is especially important in driving and sports. Traditionally, the Developmental Eye Movement (DEM) test and the King–Devick (K-D) test have been used to measure saccadic eye movement, but these only involve measurements with “adjusted time”. Therefore, a different approach is required to obtain the eye movement speed and reaction rate in detail, as some are rapid eye movements, while others are slow actions, and vice versa. This study proposed an extended method that can acquire the “rest time” and “transfer time”, as well as the “adjusted time”, by implementing a virtual reality-based DEM test, using a FOVE virtual reality (VR) head-mounted display (HMD), equipped with an eye-tracking module. This approach was tested in 30 subjects with normal vision and no ophthalmologic disease by using a 2-diopter (50-cm) distance. This allowed for measurements of the “adjusted time” and the “rest time” for focusing on each target number character, the “transfer time” for moving to the next target number character, and recording of the gaze-tracking log. The results of this experiment showed that it was possible to analyze more parameters of the saccadic eye movement with the proposed method than with the traditional methods.

Accuracy Analysis of Distinguishing the Cooperation Degree during Image Completion Test by Eye Movement Parameters.

Objective To analyze the differences in accuracy of different eye movement parameters in distinguishing the cooperation and non-cooperation during image completion test of patients with mental disorders caused by craniocerebral trauma. Methods One hundred and forty cases of patients with mental disorders caused by craniocerebral trauma who took psychiatric impairment assessments were collected. The 21 pictures from "image completion" of Wechsler intelligence test were used as stimulating pictures, then divided into cooperation group and non-cooperation group according to binomial forced-choice digit memory test and expert opinions. The eye movement parameters of research subjects during completion of images were obtained by the SMI eye-tracker. The accuracy of eye movement parameters in distinguishing the cooperation or non-cooperation of patients with mental disorders caused by craniocerebral trauma in psychiatric impairment assessments were evaluated by the ROC curve. Results During the process of the image completion test, the area under curve （AUC） value of frequency of blink, frequency of fixation, pupil size, frequency of saccade, latency of saccade, average acceleration of saccade, the average and peak longitudinal velocity of saccade was above 0.5. When it comed to a specific stimulating picture, the AUC value of frequency of blink in looking at a specific stimulating picture could be above 0.8, and the AUC value of X axis diameter of pupil size could be above 0.7. Conclusion The accuracy of eye movement parameters in distinguishing the cooperation or disguise of patients with mental disorders caused by craniocerebral trauma is related with the stimulating picture. The accuracy of frequency of blink in distinguishing cooperation and non-cooperation is better than that of other eye movement parameters.

Application of Eye Tracker in Lie Detection.

Objective To investigate the application value of eye tracking in lie detection. Methods The 40 subjects were randomly divided into two groups. The pupil diameter, fixation duration, points of fixation and blink frequency of the subjects in the experimental group in observing target stimulation and non-target stimulation were recorded with eye tracker after they accomplished the mock crime. The eye movement parameters of subjects in the control group were directly collected. The differences in eye movement parameters of the experimental group and the control group in observing target stimulation and non-target stimulation were analyzed by t-test. Pearson coefficient analysis of correlation between eye movement parameters that had differences was conducted. The effectiveness of eye movement parameters to distinguish between the experimental group and the control group was calculated by the receiver operator characteristic （ROC） curve. Results Participants from the experimental group had shorter average pupil diameter, longer average fixation duration and fewer fixation points （P<0.05）, but the differences in blink frequency had no statistical significance. The differences in the above indicators of the control group in observing target stimulation and non-target stimulation had no statistical significance. The average fixation duration showed a negative correlation with fixation points （r=-0.255, P<0.05）; the average fixation duration showed a negative correlation with average pupil diameter （r=-0.218, P<0.05）; the fixation points showed a positive correlation with average pupil diameter （r=0.09, P<0.05）. The area under the curve of average pupil diameter, average fixation duration and fixation points was 0.603, 0.621 and 0.580, respectively. Conclusion The average pupil diameter, average fixation duration and fixation points obtained by the eye tracker under laboratory conditions can be used to detect lies.

Structure of presented stimuli influences gazing behavior and choice

Well-structured stimuli presentation is essential in eye-tracking research to test predefined hypotheses reliably and to conduct relevant gazing behavior studies. Several bottom-up factors associated with stimuli presentation (such as stimuli orientation, size etc.) can influence gazing behavior. However, only a small number of scientific papers address these factors in a sensory and consumer science context and thus provide guidance to practitioners. The two presented eye-tracking studies on food images aimed at evaluating the effect of the bottom-up factors stimulus size, background of the picture, orientation of food product presentation, the evaluated products and the number of alternatives. Significant effects of product group were found in the case of all eye-movement parameters except time to first fixation and first fixation duration. In contrary, orientation significantly influenced only the time to first fixation and first fixation duration parameters. Stimulus size significantly increased fixation and dwell count, while background showed no significant effects. Furthermore, significant relationships were found between the number of presented images and eye-movement and decision time. Less time was needed in 2AFC (alternative forced choice test), 3AFC and 4AFC and significantly more time was needed to choose one alternative out of 7AFC and 8AFC. The results of the two studies show that the investigated bottom-up factors can significantly influence gazing behavior, and therefore need to be carefully considered when planning or comparing results of eye-tracking experiments.

Unbalancing the Attentional Priority Map via Gaze-Contingent Displays Induces Neglect-Like Visual Exploration.

Selective spatial attention is a crucial cognitive process that guides us to the behaviorally relevant objects in a complex visual world by using exploratory eye movements. The spatial location of objects, their (bottom-up) saliency and (top-down) relevance is assumed to be encoded in one “attentional priority map” in the brain, using different egocentric (eye-, head- and trunk-centered) spatial reference frames. In patients with hemispatial neglect, this map is supposed to be imbalanced, leading to a spatially biased exploration of the visual environment. As a proof of concept, we altered the visual saliency (and thereby attentional priority) of objects in a naturalistic scene along a left-right spatial gradient and investigated whether this can induce a bias in the exploratory eye movements of healthy humans (n = 28; all right-handed; mean age: 23 years, range 19–48). We developed a computerized mask, using high-end “gaze-contingent display (GCD)” technology, that immediately and continuously reduced the saliency of objects on the left—“left” with respect to the head (body-centered) and the current position on the retina (eye-centered). In both experimental conditions, task-free viewing and goal-driven visual search, this modification induced a mild but significant bias in visual exploration similar to hemispatial neglect. Accordingly, global eye movement parameters changed (reduced number and increased duration of fixations) and the spatial distribution of fixations indicated an attentional bias towards the right (rightward shift of first orienting, fixations favoring the scene’s outmost right over left). Our results support the concept of an attentional priority map in the brain as an interface between perception and behavior and as one pathophysiological ground of hemispatial neglect.

At first sight: robots’ subtle eye movement parameters affect human attentional engagement, spontaneous attunement and perceived human-likeness

AbstractHuman-robot interaction research could benefit from knowing how various parameters of robotic eye movement control affect specific cognitive mechanisms of the user, such as attention or perception. In the present study, we systematically teased apart control parameters of Trajectory Time of robot eye movements (rTT) between two joint positions and Fixation Duration (rFD) on each of these positions of the iCub robot. We showed recordings of these behaviors to participants and asked them to rate each video on how human-like the robot’s behavior appeared. Additionally, we recorded participants’ eye movements to examine whether the different control parameters evoked different effects on cognition and attention. We found that slow but variable robot eye movements yielded relatively higher human-likeness ratings. On the other hand, the eye-tracking data suggest that the human range of rTT is most engaging and evoked spontaneous involvement in joint attention. The pattern observed in subjective ratings was paralleled only by one measure in the implicit objective metrics, namely the frequency of spontaneous attentional following. These findings provide significant clues for controller design to improve the interaction between humans and artificial agents.

Разработка методики изучения и оценки выраженности профессиональных деформаций спортсменов на основе анализа параметров движений глаз

The study and prediction of emergence and development of occupational deformations is one of the urgent tasks in psychology. However, existing methods are questionnaires, and their results can be distorted due to self-reports by respondents. In this regard, the aim of the study was to develop a methodology for studying and assessing the severity of occupational deformations using unbiased indicators of oculomotor activity and the burnout syndrome example.&#x0D; 34 athlete-skaters took part in the experiment. As stimuli, texts of negative, positive and neut­ral content were used. The results identified a link between the severity of burnout symptoms such as “reduction of personal achievements” and “depersonalization” with eye movement parameters. In particular, the members of the “reduction of personal achievements” group, while reading texts with negative content, tried to focus less on negative words thereby avoiding them. Thus, using the parameters of eye movements, the authors conducted an unbiased assessment of text areas, to which the subjects' attention was directed. This allowed reliably identifying the behavioural strategies for subjects who suffer from burnout syndrome.

Encoding of eye movements explains reward-related activity in cerebellar simple spikes.

The cerebellum exhibits both motor and reward-related signals. However, it remains unclear whether reward is processed independently from the motor command or might reflect the motor consequences of the reward drive. To test how reward-related signals interact with sensorimotor processing in the cerebellum, we recorded Purkinje cell simple spike activity in the cerebellar floccular complex while monkeys were engaged in smooth pursuit eye movement tasks. The color of the target signaled the size of the reward the monkeys would receive at the end of the target motion. When the tracking task presented a single target, both pursuit and neural activity were only slightly modulated by the reward size. The reward modulations in single cells were rarely large enough to be detected. These modulations were only significant in the population analysis when we averaged across many neurons. In two-target tasks where the monkey learned to select based on the size of the reward outcome, both behavior and neural activity adapted rapidly. In both the single- and two-target tasks, the size of the reward-related modulation matched the size of the effect of reward on behavior. Thus, unlike cortical activity in eye movement structures, the reward-related signals could not be dissociated from the motor command. These results suggest that reward information is integrated with the eye movement command upstream of the Purkinje cells in the floccular complex. Thus reward-related modulations of the simple spikes are akin to modulations found in motor behavior and not to the central processing of the reward value.NEW & NOTEWORTHY Disentangling sensorimotor and reward signals is only possible if these signals do not completely overlap. We recorded activity in the floccular complex of the cerebellum while monkeys performed tasks designed to separate representations of reward from those of movement. Activity modulation by reward could be accounted for by the coding of eye movement parameters, suggesting that reward information is already integrated into motor commands upstream of the floccular complex.

Lexically or grammatically adapted texts: what is easier to process for secondary school children?

Abstract This article presents the results of an eye-tracking experiment on Russian language material, exploring the reading process in secondary school children with general speech underdevelopment. The objective of the study is to reveal what type of a text is better to use to make the reading and comprehension easier: lexically adapted text or grammatically adapted text? The data from Russian-speaking participants from the compulsory school (experimental group) and 28 secondary school children with normal speech development (control group) indicate that both types of adaptation proved to be efficient for recalling the information from the text. Though, we revealed that in teenagers with language disorders in anamnesis lower perceptual processes are partially compensated (parameters of eye movements), but higher comprehension processes remain affected.

Cognitive activity in limited time conditions: individual and typological features

Rapid socio-economic and technological innovations, quick pace of life, colossal information loads and limited time are highly common for the society of the XXI century. Reducing performance time is one of the powerful stress factors that affect the adaptation processes and the psychophysiological state of the body. The result of a temporary limitation in task implementation may result in the optimization of all processes in the body and maximized work efficiency or have an opposite effect. There are many physiological markers of stress response development in the human body, one of which is the parameters of eye movement. Evidence exists that representatives with different types of autonomic regulation of functions have specific manifestations of stress reactions that are traced in the oculomotor activity. In this research, seventy students of the Northern (Arctic) Federal University named after M.V. Lomonosov, Russia, were examined for the study of their oculomotor reactions. Students with different autonomic status solved cognitive tasks either in a limited or unlimited time. The most sensitive parameters of oculomotor reactions were revealed when participants were reading under a time limit. It has been discovered that representatives with different vegetative status have specific manifestations of cognitive activity under the conditions of restricted time. The study shows that the efficiency of processing visual information in a limited time is accompanied by an increase in frequency parameters and a decrease in the duration of fixations identified in representatives with normotonic vegetative status.