Saccade Amplitude Research Articles

Individuals with High Metacognitive Ability Are Better at Divergent and Convergent Thinking.

Is metacognitive ability a predictor of creative performance? Previous studies have produced conflicting findings. To clarify whether this relationship exists, the current study used eye tracking techniques and vocal thinking reports to explore creativity differences in individuals with different levels of metacognitive ability. One hundred and twelve participants completed the Metacognitive Ability scale, and were divided into two groups (with thirty participants in each group) based on their metacognition scores (the highest and lowest 27% of metacognitive ability scores). Then, participants in both groups completed two creative thinking tasks (AUT and CCRAT) while their eye behaviors were recorded by eye tracking. The results showed that participants with high metacognitive ability were better at divergent thinking, as evidenced by greater fixation and saccade counts, as well as smaller saccade amplitudes in the AUT task. In addition, Bayesian analyses provide anecdotal evidence that participants with high metacognitive ability tended to be better at convergent thinking. Furthermore, eye tracking results demonstrated that they exhibited longer fixation duration and more fixation count on the materials in the CCRAT task. These findings reflect an important role of metacognition in creative thinking, especially in divergent thinking.

Rapid Audiovisual Integration Guides Predictive Actions.

Natural movements, such as catching a ball or capturing prey, typically involve multiple senses. Yet, laboratory studies on human movements commonly focus solely on vision and ignore sound. Here, we ask how visual and auditory signals are integrated to guide interceptive movements. Human observers tracked the brief launch of a simulated baseball, randomly paired with batting sounds of varying intensities, and made a quick pointing movement at the ball. Movement end points revealed systematic overestimation of target speed when the ball launch was paired with a loud versus a quiet sound, although sound was never informative. This effect was modulated by the availability of visual information; sounds biased interception when the visual presentation duration of the ball was short. Amplitude of the first catch-up saccade, occurring ∼125 ms after target launch, revealed early integration of audiovisual information for trajectory estimation. This sound-induced bias was reversed during later predictive saccades when more visual information was available. Our findings suggest that auditory and visual signals are integrated to guide interception and that this integration process must occur early at a neural site that receives auditory and visual signals within an ultrashort time span.

Abnormal saccade profiles in hereditary spinocerebellar degeneration reveal cerebellar contribution to visually guided saccades

ObjectiveTo study how the pathophysiology underlying hereditary spinocerebellar degeneration (spinocerebellar ataxia; SCA) with pure cerebellar manifestation evolves with disease progression using saccade recordings. MethodsWe recorded visually- (VGS) and memory-guided saccade (MGS) task performance in a homogeneous population of 20 genetically proven SCA patients (12 SCA6 and eight SCA31 patients) and 19 normal controls. ResultsFor VGS but not MGS, saccade latency and amplitude were increased and more variable than those in normal subjects, which correlated with cerebellar symptom severity assessed using the International Cooperative Ataxia Rating Scale (ICARS). Parameters with significant correlations with cerebellar symptoms showed an aggravation after disease stage progression (ICARS > 50). The saccade velocity profile exhibited shortened acceleration and prolonged deceleration, which also correlated with disease progression. The main sequence relationship between saccade amplitude and peak velocity as well as saccade inhibitory control were preserved. ConclusionsThe cerebellum may be involved in initiating VGS, which was aggravated acutely during disease stage progression. Dysfunction associated with disease progression occurs mainly in the cerebellum and brainstem interaction but may also eventually involve cortical saccade processing. SignificanceSaccade recording can reveal cerebellar pathophysiology underlying SCA with disease progression.

Quantitative Model Study of the Psychological Recovery Benefit of Landscape Environment Based on Eye Movement Tracking Technology

From the perspective of landscape and human health, we use the Self-Rating Restoration Scale (SRRS) as a tool to explore the mental health restoration benefits brought by a landscape environment to individuals and explore the characteristics of individual movement behavior when viewing the landscape through the eye movement tracking technology. We selected average blink duration, average gaze length, average saccade amplitude, blink number, number of fixation points, saccade number, and average pupil diameter as experimental indicators for data monitoring. Based on the eye movement heat map obtained by data visualization processing and the results of correlation analysis, we summarized the eye movement behavior characteristics of individuals when viewing the restorative landscape. We try to construct a quantitative evaluation model of the landscape mental recovery benefit with the objective eye movement index as the independent variable through the method of curve estimation. The study results show that individual eye movement behavior is related to the landscape type and the level of psychological recovery is also different. (1)The more singular that the constituent elements are, the more widespread and concentrated the regional distribution of individual attention areas, and the relative psychological recovery benefit is relatively weak. The more complex that the constituent elements are, the more scattered and smaller the individual interest area, and the psychological recovery benefit is better. Brightly colored, dynamic landscapes are easier to form areas of interest to improve the psychological response to the human body. (2) The psychological recovery benefit of the landscape is directly proportional to the changing trend of the average blink duration, number of fixation points, and number of saccades and is inversely proportional to the changing trend of the average gaze length. (3) The objective eye movement index of average blink duration can quantitatively predict the psychological recovery benefit value of the landscape environment. The number of fixation points, the number of saccades, and the average fixation length could predict the psychological recovery benefits of the landscape, while the other indicators had no prediction effect.

Transforming Psychological Testing With Saccadic Responses: Internal Consistency is High for Rorschach and Facial Expressions.

Psychologists have long been interested in the underlying visual perceptual processes associated with forming responses to certain psychological tests, including the Rorschach Ink Blot Test, which modern users conceptualize as a conceptual problem-solving task. Accordingly, we used eye tracking technology to assess the internal consistency of saccadic responses to both the Rorschach Ink Blot Test and a facial expression task. Internal consistency was highest for eye Fixation Duration (FD) and Saccade Amplitude (SA), and both FD and SA measures in the Rorschach were positively related to the same measures in the facial expression task. Given this high internal consistency of FD and SA for viewing Rorschach ink blots and viewing pictures from well-known collections of facial expressions, and given high correlations between these eye tracking measures across the two tasks, FD and SA may now be used in further studies of eye movements in visuo-attentive psychological/neuropsychological tests (e.g., the Thematic Apperception Test). Reliability of these eye movement measures across tasks enables their use for better understanding of underlying visual processes and improved interpretations of the meaning of behavioral responses to psychological/neuropsychological tests.

Visual Search Strategies in Badminton Serve : Expertise and Performance(Sucess or Failure) Perspective

PURPOSE The main purpose of this study was to examine the difference in visual search strategies based on the skill level in success and failure cases in badminton short serves.METHODS To this end, six badminton experts (experience: more than 10 years) and six novices (less than 1 years) participated. The participants’ eye movement was recorded during each trial, and mean fixation duration, mean saccade amplitude, percentage of viewing time on each fixation location, final fixation duration, and gaze entropy were analyzed.RESULTS First, the mean fixation duration did not differ significantly, but the mean saccade amplitude increased when expert players failed to perform the serve successfully. Second, the percentage of viewing time on each location results showed that the overall viewing time was lower when the performance was unsuccessful, and the expert players fixated longer time viewing the net and space when they made a successful serve. Third, expert players showed longer QE than novice players when they made a successful serve. Finally, the gaze entropy results showed that expert players showed greater gaze entropy during successful performance, indicating that the gaze pattern was randomly distributed across trials.CONCLUSIONS When learning a badminton serve, we should fully recognize and explore the receiver’s location and external environment, and subsequently, before initiating serve movement, focus on the net or space between the receiver’s racquet and shoulders to make a more successful performance. In addition, we should make various patterns of the visual search strategy, rather than the fixed or consistent search strategy, to deceive receivers.

Analysing Vestibulo-ocular and Oculomotor Reflex with Advancing Age

Background: Video Head Impulse Test (v-HIT) and saccades test of Videonystagmography (VNG) are used clinically to differentially diagnose patients into peripheral and central vestibular pathologies. However, age and clinic specific norms are required for both the tests. Aims: To investigate if there is any changes in parameters of v-HIT and saccades test with advancing age. Design: A prospective cross sectional research design study was carried out from April 2023 to June 2023 at the department of School of Audiology & Speech Language Pathology. Method & Materials: Individuals between the age range of 20- 80 years were included in the study. Participants with no history of vertigo, neurodegenerative disorders, negative Fukuda stepping and Romberg test were included. All of them underwent through v-HIT followed by saccades test of VNG. Results: Total 60 individuals participated in the study. Mean and SD values for gain, number of saccades and amplitude of saccades were determined as the parameters of v-HIT. On studying effect of age on vHIT, gain parameter was found to be changing with advancing age. Further, Mean and SD were also determined for velocity, precision and latency parameter of saccade test which was performed in horizontal and vertical planes at 0.3 Hz, 0.45 Hz and 0.6 Hz frequency of target stimulus. latency parameters were observed to be increasing with increase in age of participants. Conclusion: Age specific norms are necessary especially for gain parameter of vHIT test and latency parameter of saccade test

Saccade Analysis in Patients With Orbital-Wall Fractures Without Diplopia.

This study aimed to analyze saccades in patients with orbital-wall fractures with little or no ocular motor impairment. We included 7 eyes of 7 patients with unoperated orbital-wall fractures (3 cases of orbital-floor fractures and 4 cases of medial orbital-wall fractures) with mild or no diplopia who presented to our hospital between August 2019 and March 2021. Eye movements were assessed at the first visit and after 1 month using the Hess area ratio according to the Hess screen test, binocular single vision (BSV) scores (total 59 points) obtained using Goldman perimetry, and maximum velocity and amplitude of saccades within 15 degrees obtained using an eye tracker system. Hess area ratio and BSV scores at the first visit and after 1 month were 88.6±8.2% and 97.4±3.6% and 49.6±8.5 points and 53.5±6.6 points, respectively, with no significant change (Hess area ratio, P =0.06; BSV, P =0.44). Next, the authors compared the velocity and amplitude of the saccades between the first visit and 1 month later and found no significant changes in any of the 4 directions (adduction, abduction, upgaze, and downgaze). Similarly, no significant differences were observed between the velocity and amplitude of the saccades between the injured and noninjured eyes, both at the first visit and after 1 month. In patients with orbital-wall fractures with little or no eye movement impairment, eye tracker-based saccade analysis showed that the saccade velocity and amplitude did not change during the natural course of healing of the fracture.

Exploring the Visual Attention Mechanism of Long-Distance Driving in an Underground Construction Cavern: Eye-Tracking and Simulated Driving

Prolonged driving is necessary in underground construction caverns to transport materials, muck, and personnel, exposing drivers to high-risk and complex environments. Despite previous studies on attention and gaze prediction at tunnel exit-inlet areas, a significant gap remains due to the neglect of dual influences of long-distance driving and complex cues. To address this gap, this study establishes an experimental scenario in a construction environment, utilizing eye-tracking and simulated driving to collect drivers’ eye movement data. An analysis method is proposed to explore the visual change trend by examining the evolution of attention and calculating the possibility of visual cues being perceived at different driving stages to identify the attentional selection mechanism. The findings reveal that as driving time increases, fixation time decreases, saccade amplitude increases, and some fixations transform into unconscious saccades. Moreover, a phenomenon of “visual adaptation” occurs over time, reducing visual sensitivity to environmental information. At the start of driving, colorful stimuli and safety-related information compete for visual resources, while safety-related signs, particularly warning signs, always attract drivers’ attention. However, signs around intense light are often ignored. This study provides a scientific basis for transport safety in the construction environment of underground caverns.

P.017 Convergent and contrasting modulation of saccade and pupil responses by several neurodegenerative diseases during free viewing of video clips

Background: Saccade and pupil responses are potential neurodegenerative disease biomarkers due to overlap between oculomotor circuitry and disease-affected areas. Instruction-based tasks have previously been examined as biomarker sources, but are arduous for patients with limited cognitive abilities; additionally, few studies have evaluated multiple neurodegenerative pathologies concurrently. Methods: The Ontario Neurodegenerative Disease Research Initiative recruited individuals with Alzheimer’s disease (AD), mild cognitive impairment (MCI), amyotrophic lateral sclerosis (ALS), frontotemporal dementia, progressive supranuclear palsy, or Parkinson’s disease (PD). Patients (n=274, age 40-86) and healthy controls (n=101, age 55-86) viewed 10 minutes of frequently changing video clips without instruction while their eyes were tracked. We evaluated differences in saccade and pupil parameters (e.g. saccade frequency and amplitude, pupil size, responses to clip changes) between groups. Results: Preliminary data indicates low-level behavioural alterations in multiple disease cohorts: increased centre bias, lower overall saccade rate and reduced saccade amplitude. After clip changes, patient groups generally demonstrated lower saccade rate but higher microsaccade rate following clip change to varying degrees. Additionally, pupil responses were blunted (AD, MCI, ALS) or exaggerated (PD). Conclusions: This task may generate behavioural biomarkers even in cognitively impaired populations. Future work should explore the possible effects of factors such as medication and disease stage.

Adaptive changes to saccade amplitude and target localization do not require pre-saccadic target visibility

The accuracy of saccadic eye movements is maintained by saccadic adaptation, a learning mechanism that is proposed to rely on visual prediction error, i.e., a mismatch between the pre-saccadically predicted and post-saccadically experienced position of the saccade target. However, recent research indicates that saccadic adaptation might be driven by postdictive motor error, i.e., a retrospective estimation of the pre-saccadic target position based on the post-saccadic image. We investigated whether oculomotor behavior can be adapted based on post-saccadic target information alone. We measured eye movements and localization judgements as participants aimed saccades at an initially invisible target, which was always shown only after the saccade. Each such trial was followed by either a pre- or a post-saccadic localization trial. The target position was fixed for the first 100 trials of the experiment and, during the following 200 trials, successively shifted inward or outward. Saccade amplitude and the pre- and post-saccadic localization judgements adjusted to the changing target position. Our results suggest that post-saccadic information is sufficient to induce error-reducing adaptive changes in saccade amplitude and target localization, possibly reflecting continuous updating of the estimated pre-saccadic target location driven by postdictive motor error.

Reading numbers is harder than reading words: An eye-tracking study

We recorded the eye movements of adults reading aloud short (four digit) and long (eight to 11 digit) Arabic numerals compared to matched-in-length words and pseudowords. We presented each item in isolation, at the center of the screen. Participants read each item aloud at their pace, and then pressed the spacebar to display the next item. Reading accuracy was 99 %. Results showed that adults make 2.5 times more fixations when reading short numerals compared to short words, and up to 7 times more fixations when reading long numerals with respect to long words. Similarly, adults make 3 times more saccades when reading short numerals compared to short words, and up to 9 times more saccades when reading long numerals with respect to long words. Fixation duration and saccade amplitude stay almost the same when reading short numerals with respect to short words. However, fixation duration increases by ∼50 ms when reading long numerals (∼300 ms) with respect to long words (∼250 ms), and saccade amplitude decreases up to 0.83 characters when reading long numerals with respect to long words. The pattern of findings for long numerals—more and shorter saccades as well as more and longer fixations—shows the extent to which reading long Arabic numerals is a cognitively costly task. Within the phonographic writing system, this pattern of eye movements stands for the use of the sublexical print-to-sound correspondence rules. The data highlight that reading large numerals is an unautomatized activity and that Arabic numerals must be converted into their oral form by a step-by-step process even by expert readers.

Risk Assessment of Distracted Driving Behavior Based on Visual Stability Coefficient

Cell phone call operations during driving can lead to distraction and cause potential safety hazards. In order to quantitatively characterize the influence of cell phone call mode on the driver’s visual behavior in different traffic conditions and to analyze the risk level of distracted driving from the visual level, a distracted driving simulation test was carried out based on a driving simulator and eye tracker. The eye movement data of drivers during normal driving, hands-free call, and video call under two typical traffic conditions of free flow and congested flow on the urban expressway were collected. Firstly, four visual characteristics indicators that were highly sensitive to traffic conditions and driving states were selected in terms of visual field range, visual recognition, visual search, and visual load, which were the information entropy of fixation area (IEFA), saccade amplitude, peak-to-average ratio of saccade velocity (PARSV), and relative change intensity of pupil area (RCPA). Then, based on the improved CRITIC method, the visual stability coefficient (VSC) was constructed as a new indicator to comprehensively assess the risk level of the driving state, and the assessment criteria were divided. Finally, the grey correlation analysis method was introduced to verify the assessment effect of VSC. The results show that different cell phone call modes increased driving risk in both traffic conditions. Among them, the negative influence of video calls on driving safety was significantly higher than that of hands-free calls, with a significant decrease in VSC, and the drivers’ VSC in the free flow scenario was more sensitive to the impact of cell phone call operation, and the driving risk increased significantly during distracted driving. The VSC can quantitatively assess driving risk from the perspective of visual psychological safety and contributes to the development of corresponding early warning and control measures.

Analyses of Head-Impulse Tests in Patients With Posterior Circulation Stroke and Vestibular Neuritis.

The interpretation of video head-impulse tests (video-HITs) can often be complicated, limiting their clinical utility in acute vestibular syndrome. We aimed to determine video-HIT findings in patients with posterior circulation strokes (PCSs) and vestibular neuritis (VN). We retrospectively analyzed the results of video-HITs in 59 patients with PCS. Irrespective of the actual lesion revealed later on MRIs, ipsilateral and contralateral sides were assigned according to the direction of slow phase of spontaneous nystagmus (SN). Then, the patterns of video-HIT findings were classified according to the vestibulo-ocular reflex (VOR) gain for the horizontal canals; (1) ipsilaterally positive, (2) contralaterally positive, (3) bilaterally normal, and (4) bilaterally positive. The abnormal responses were further defined into (5) wrong-way saccades, (6) perverted, and (7) early acceleration followed by premature deceleration. We also analyzed the asymmetry of the corrective saccadic amplitude between the sides, calculated from the sum of cumulative saccadic amplitudes on both sides. The results were compared with video-HIT results from 71 patients with VN. Video-HITs were normal in 32 (54%), ipsilaterally positive in 11 (19%), bilaterally positive in 10 (17%), and contralaterally positive in 6 (10%) patients with PCS. Wrong-way saccades were more frequently observed in VN than in PCS (31/71 [44%] vs 5/59 [8%], p < 0.001). Saccadic amplitude asymmetry was greater in VN than in PCS (median 100% [interquartile range 82-144, 95% CI 109-160] vs 0% [-29 to 34, -10 to 22, p < 0.001]). When differentiating VN from PCS, the sensitivity was 81.7%, and specificity was 91.5% at the cutoff value of 71% for saccadic amplitude asymmetry with an area under the curve (AUC) of 0.91 (95% CI 0.86-0.97). The AUC for saccadic amplitude asymmetry was larger than that for the ipsilateral VOR gain (p = 0.041) and other parameters. Patients with PCS may show various head-impulse responses that deviate from the findings expected in VN, which include normal, contralaterally positive, and negative saccadic amplitude asymmetry (i.e., greater cumulative saccadic amplitude contralaterally). A thorough analysis of corrective saccades in video-HITs can improve the differentiation of PCS from VN even before MRIs.

Metacognitive prompts and numerical ordinality in solving word problems: An eye-tracking study.

The ability to translate concrete manipulatives into abstract mathematical formulas can aid in the solving of mathematical word problems among students, and metacognitive prompts play a significant role in enhancing this process. Based on the concept of semantic congruence, we explored the effects of metacognitive prompts and numerical ordinality on information searching and cognitive processing, throughout the process of solving mathematical word problems among primary school students in China. Participants included 73 primary school students (38 boys and 35 girls) with normal or corrected visual acuity. This study was based on a 2 (prompt information: no-prompt, metacognitive-prompt) × 2 (number attribute: cardinal number, ordinal number) mixed experimental design. We analysed multiple eye-movement indices, such as fixation duration, saccadic amplitude, and pupil size, since they pertained to the areas of interest. When solving both types of problems, pupil sizes were significantly smaller under the metacognitive-prompt condition compared with the no-prompt condition, and shorter dwell time for specific sentences, conditional on metacognitive prompts, indicated the optimization of the presented algorithm. Additionally, the levels of fixation durations and saccadic amplitudes were significantly higher when solving ordinal number word problems compared with solving ordinal number problems, indicating that primary school students were less efficient in reading and faced increased levels of difficulty when solving ordinal number problems. The results indicate that for Chinese upper-grade primary school students, cognitive load was lower in the metacognitive prompting condition and when solving cardinal problems, and higher when solving ordinal problems.

EHTask: Recognizing User Tasks From Eye and Head Movements in Immersive Virtual Reality.

Understanding human visual attention in immersive virtual reality (VR) is crucial for many important applications, including gaze prediction, gaze guidance, and gaze-contingent rendering. However, previous works on visual attention analysis typically only explored one specific VR task and paid less attention to the differences between different tasks. Moreover, existing task recognition methods typically focused on 2D viewing conditions and only explored the effectiveness of human eye movements. We first collect eye and head movements of 30 participants performing four tasks, i.e., Free viewing, Visual search, Saliency, and Track, in 15 360-degree VR videos. Using this dataset, we analyze the patterns of human eye and head movements and reveal significant differences across different tasks in terms of fixation duration, saccade amplitude, head rotation velocity, and eye-head coordination. We then propose EHTask - a novel learning-based method that employs eye and head movements to recognize user tasks in VR. We show that our method significantly outperforms the state-of-the-art methods derived from 2D viewing conditions both on our dataset (accuracy of 84.4% versus 62.8%) and on a real-world dataset ( 61.9% versus 44.1%). As such, our work provides meaningful insights into human visual attention under different VR tasks and guides future work on recognizing user tasks in VR.

Flipping the world upside down: Using eye tracking in virtual reality to study visual search in inverted scenes.

Image inversion is a powerful tool for investigating cognitive mechanisms of visual perception. However, studies have mainly used inversion in paradigms presented on twodimensional computer screens. It remains open whether disruptive effects of inversion also hold true in more naturalistic scenarios. In our study, we used scene inversion in virtual reality in combination with eye tracking to investigate the mechanisms of repeated visual search through three-dimensional immersive indoor scenes. Scene inversion affected all gaze and head measures except fixation durations and saccade amplitudes. Our behavioral results, surprisingly, did not entirely follow as hypothesized: While search efficiency dropped significantly in inverted scenes, participants did not utilize more memory as measured by search time slopes. This indicates that despite the disruption, participants did not try to compensate the increased difficulty by using more memory. Our study highlights the importance of investigating classical experimental paradigms in more naturalistic scenarios to advance research on daily human behavior.

The influence of scene tilt on saccade directions is amplitude dependent

When exploring a visual scene, humans make more saccades in the horizontal direction than any other direction. While many have shown that the horizontal saccade bias rotates in response to scene tilt, it is unclear whether this effect depends on saccade amplitude. We addressed this question by examining the effect of image tilt on the saccade direction distributions recorded during freely viewing natural scenes. Participants (n = 20) viewed scenes tilted at −30°, 0°, and 30°. Saccade distributions during free viewing rotated by an angle of 12.1° ± 6.7° (t(19) = 8.04, p < 0.001) in the direction of the image tilt. When we partitioned the saccades according to their amplitude we found that small amplitude saccades occurred most in the horizontal direction while large amplitude saccades were more oriented to the scene tilt (p < 0.001). To further study the characteristics of small saccades and how they are affected by scene tilt, we looked at the effect of image tilt on small fixational saccades made while fixating a central target amidst a larger scene and found that fixational saccade distributions did not rotate with scene tilt (−0.3° ±1.7° degrees; t(19) = −0.8, p = 0.39). These results suggest a combined effect of two reference frames in saccade generation: one egocentric reference frame that dominates for small saccades, biases them horizontally, and may be common for different tasks, and another allocentric reference frame that biases larger saccades along the orientation of an image during free viewing.

Early detection of cognitive decline in Alzheimer's disease using eye tracking.

Patients with Alzheimer's disease (AD) are known to exhibit visuospatial processing impairment, as reflected in eye movements from the early stages of the disease. We investigated whether the pattern of gaze exploration during visual tasks could be useful for detecting cognitive decline at the earliest stage. Sixteen AD patients (age: 79.1 ± 7.9 years, Mini Mental State Examination [MMSE] score: 17.7 ± 5.3, mean ± standard deviation) and 16 control subjects (age: 79.4 ± 4.6, MMSE score: 26.9 ± 2.4) participated. In the visual memory task, subjects memorized presented line drawings for later recall. In the visual search tasks, they searched for a target Landolt ring of specific orientation (serial search task) or color (pop-out task) embedded among arrays of distractors. Using video-oculography, saccade parameters, patterns of gaze exploration, and pupil size change during task performance were recorded and compared between AD and control subjects. In the visual memory task, the number of informative regions of interest (ROIs) fixated was significantly reduced in AD patients compared to control subjects. In the visual search task, AD patients took a significantly longer time and more saccades to detect the target in the serial but not in pop-out search. In both tasks, there was no significant difference in the saccade frequency and amplitude between groups. On-task pupil modulation during the serial search task was decreased in AD. The number of ROIs fixated in the visual memory task and search time and saccade numbers in the serial search task differentiated both groups of subjects with high sensitivity, whereas saccade parameters of pupil size modulation were effective in confirming normal cognition from cognitive decline with high specificity. Reduced fixation on informative ROIs reflected impaired attentional allocation. Increased search time and saccade numbers in the visual search task indicated inefficient visual processing. Decreased on-task pupil size during visual search suggested decreased pupil modulation with cognitive load in AD patients, reflecting impaired function of the locus coeruleus. When patients perform the combination of these tasks to visualize multiple aspects of visuospatial processing, cognitive decline can be detected at an early stage with high sensitivity and specificity and its progression be evaluated.

The influence of the stimulus category on the characteristics of eye movements in visual search

Introduction. The speed and efficiency of visual search are important characteristics of the activities of a significant range of specialists working with visual information. Specialists have carefully studied the features of visual search from the point of view of cognitive psychology and in connection with the modeling of oculomotor activity. It has been shown that its effectiveness and the parameters of search eye movements are influenced by both stimulation factors and some cognitive factors (features of the subject's preset, the influence of previous search stages, etc.). We assume that the search features are also related to how well a person represents the desired stimulus: whether it belongs to a familiar semantic category, how accurate and unambiguous its visual representation is.&#x0D; The study aims to explore the relationship between the parameters of eye movements in visual search and the features of the mental representation of the target object.&#x0D; Materials and methods. We have created sets of stimuli belonging to different semantic categories, characterized by different accuracy of mental representations, but having similar sensory qualities. Each object (both the target stimulus and the distractor) in the search field was a black circle on a white background with four black segments inside. The segments formed one of three configurations: a) a face; b) a Roman numeral; c) a random configuration. The study participants were asked to find in a matrix of 84 objects a specific target stimulus belonging to one of the three specified categories. The scientists recorded the participant's eye movements during the search.&#x0D; Results. The results of the study generally confirmed the hypothesis about the relationship of search characteristics with the category of the target object. The smallest number of errors, the minimum duration of fixation and the maximum amplitude of saccades characterized the search for Roman numerals — objects with a well-formed and well-defined visual representation. The most difficult, as expected, was the search for objects representing random configurations of segments.&#x0D; Limitations. Since the study was largely exploratory in nature, the results obtained require clarification on a wider sample. It is possible that the characteristics of the search were influenced by such a factor not controlled in the study as the configuration of the lines, namely, the presence or absence of their intersections, which should be taken into account in further work.&#x0D; Conclusions. The better the visual representation of the target object is formed, the more successful its search is. In this case, eye movements are characterized by a shorter duration of fixation and a higher frequency of saccades of greater amplitude.&#x0D; Ethics. The study was conducted in compliance with the ethical principles set out in the Helsinki Declaration of the World Medical Association, all participants gave voluntary informed consent.