Gaze Fixation Research Articles

OCTA and Microperimetry Changes Preceding the Appearance of Diabetic Retinopathy in Patients with Type 1 Diabetes

Purpose to evaluate changes in retinal microvasculature and sensitivity (RS) preceding the appearance of diabetic retinopathy (DR) among patients with type 1 diabetes (T1D). Methods in this observational cross-sectional cohort study, vascular parameters measured by OCTA and RS evaluated by microperimetry were assessed in patients with T1D without DR (no-DR), T1D with mild DR (m-DR), and healthy controls. Results Sixty-two eyes of 31 patients with T1D and 40 eyes of 20 healthy patients were included. OCTA examinations did not yield any significant differences in terms of perfusion density (PD), vascular density (VD), foveal avascular zone (FAZ) area, FAZ perimeter or FAZ circularity between patients with diabetes (no-DR vs. m-DR). However, comparisons between healthy controls and patients with diabetes (both no-DR and m-DR groups) revealed statistically significant differences in PD, VD, and FAZ area. Similarly, no significant differences were observed between no-DR and m-DR groups regarding RS, gaze fixation stability (GFS), or macular integrity (MI). Nevertheless, mean RS and MI were significantly impaired in patients with T1D, both in no-DR and m-DR groups, compared to healthy controls. A statistically significant positive correlation was observed between RS and PD and between FAZ area and RS. Conclusion although no differences were found between patients with diabetes without DR and those with mild DR, these patients already demonstrated some degree of retinal impairment, both structural and functional, when compared to healthy controls. Our data support the hypothesis that neurodegeneration occurs together with microvascular damage at early stages of diabetes.

Bridging Human and Machine Intelligence: Reverse-Engineering Radiologist Intentions for Clinical Trust and Adoption

In the rapidly evolving landscape of medical imaging, the integration of artificial intelligence (AI) with clinical expertise offers unprecedented opportunities to enhance diagnostic precision and accuracy. Yet, the "black box" nature of AI models often limits their integration into clinical practice, where transparency and interpretability are important. This paper presents a novel system leveraging the Large Multimodal Model (LMM) to bridge the gap between AI predictions and the cognitive processes of radiologists. This system consists of two core modules, Temporally Grounded Intention Detection (TGID) and Region Extraction (RE). The TGID module predicts the radiologist's intentions by analyzing eye gaze fixation heatmap videos and corresponding radiology reports. Additionally, the RE module extracts regions of interest that align with these intentions, mirroring the radiologist’s diagnostic focus. This approach introduces a new task, radiologist intention detection, and is the first application of Dense Video Captioning (DVC) in the medical domain. By making AI systems more interpretable and aligned with radiologist’s cognitive processes, this proposed system aims to enhance trust, improve diagnostic accuracy, and support medical education. Additionally, it holds the potential for automated error correction, guiding junior radiologists, and fostering more effective training and feedback mechanisms. This work sets a precedent for future research in AI-driven healthcare, offering a pathway towards transparent, trustworthy, and human-centered AI systems. We evaluated this model using NLG(Natural Language Generation), time-related, and vision-based metrics, demonstrating superior performance in generating temporally grounded intentions on REFLACX and EGD-CXR datasets. This model also demonstrated strong predictive accuracy in overlap scores for medical abnormalities and effective region extraction with high IoU(Intersection over Union), especially in complex cases like cardiomegaly and edema. These results highlight the system's potential to enhance diagnostic accuracy and support continuous learning in radiology. We are also releasing the source code for our project, available here.

Voluntary Attention Assessing Tests in Children with Neurodevelopmental Disorders Using Eye Tracking.

Background/Objectives: The development of techniques for assessing cognitive functions using eye tracking is particularly important for children with developmental disabilities. In this paper, we present pilot results from the validation of two methods for assessing voluntary attention based on eye tracking. Methods: The study involved 80 children aged 3 to 8 years with neurodevelopmental disorders. Children performed two eye-tracking tests in which they had to 'catch' a stimulus by looking at it. They also completed the Attention Sustained subtest of the Leiter-3 International Performance Scale. In the first test, the stimuli were presented at different locations on the screen in subtests with stimuli onset asynchrony of 2 s and 1 s. A translucent blue marker marked the position of the gaze on the screen. The number of trials in which the gaze marker approached the stimulus was determined. In the second test, the location of the stimuli on the screen was changed based on gaze fixation in the ROI area. The time taken to complete the task was evaluated. Results: The results of both eye-tracking tests showed significant correlations with scores on the Attention Sustained Leiter-3 subtest and significant test-retest reliability. Conclusions: The results indicate that the present eye-tracking tests can be used for assessing voluntary attention in children with some neurodevelopmental disorders, and further research is warranted to assess the feasibility of these tests for a broader range of developmental disorders. Our findings could have practical implications for the early intervention and ongoing monitoring of attention-related issues.

Just-in-time: Gaze guidance in natural behavior.

Natural eye movements have primarily been studied for over-learned activities such as tea-making, sandwich-making, and hand-washing, which have a fixed sequence of associated actions. These studies demonstrate a sequential activation of low-level cognitive schemas facilitating task completion. However, whether these action schemas are activated in the same pattern when a task is novel and a sequence of actions must be planned in the moment is unclear. Here, we recorded gaze and body movements in a naturalistic task to study action-oriented gaze behavior. In a virtual environment, subjects moved objects on a life-size shelf to achieve a given order. To compel cognitive planning, we added complexity to the sorting tasks. Fixations aligned with the action onset showed gaze as tightly coupled with the action sequence, and task complexity moderately affected the proportion of fixations on the task-relevant regions. Our analysis revealed that gaze fixations were allocated to action-relevant targets just in time. Planning behavior predominantly corresponded to a greater visual search for task-relevant objects before the action onset. The results support the idea that natural behavior relies on the frugal use of working memory, and humans refrain from encoding objects in the environment to plan long-term actions. Instead, they prefer just-in-time planning by searching for action-relevant items at the moment, directing their body and hand to it, monitoring the action until it is terminated, and moving on to the following action.

Infrared thermal imaging and eye-tracking for deception detection: a laboratory study

Despite significant advances in deception detection in forensic psychology using polygraphy, there is a lack of empirical evidence for the potential of deception detection in ordinary situations of simple conversation where contact and invasive measurement methods are not appropriate. To address this issue, we used two strategies: 1) a non-invasive observation of facial thermal changes and gaze behaviour under deceptive and truthful conditions and 2) combination of prepared and unprepared questions during an interview. We used a within-person experimental design where responses from 16 participants were recorded, using infrared thermal imaging (fITI) and eye-tracking to measure the dependent variables (i.e., thermal changes of the nose, cheeks and forehead and gaze fixations of the interviewer’s eyes). The independent variables were veracity (truth vs. lie) and type of scenarios (prepared vs. spontaneous). Mixed-effects regression models were used to analyse the effect of lying and effect of preparation. Veracity did not significantly modulate any physiological marker, but forehead and cheek temperature were significantly modulated by the different scenario conditions in the expected direction. Multiple comparisons revealed a significant modulation of eye fixations by both the lying and scenario conditions, with eye fixations being lower in the spontaneous scenarios and higher in the prepared deceptive conditions. The results underline the significant influence of arousal and cognitive load on individual variability in all dependent variables and provide essential insights for future research into the physiological and behavioural aspects of deception detection. This study lays the foundation for the use of fITI and eye-tracking under certain experimental conditions of an ordinary conversation in content and emphasises the role of (un)preparation for the accuracy of deception detection.

Regional tuning of photoreceptor adaptation in the primate retina

Adaptation in cone photoreceptors allows our visual system to effectively operate over an enormous range of light intensities. However, little is known about the properties of cone adaptation in the specialized region of the primate central retina called the fovea, which is densely packed with cones and mediates high-acuity central vision. Here we show that macaque foveal cones exhibit weaker and slower luminance adaptation compared to cones in the peripheral retina. We find that this difference in adaptive properties between foveal and peripheral cones is due to differences in the magnitude of a hyperpolarization-activated current, Ih. This Ih current regulates the strength and time course of luminance adaptation in peripheral cones where it is more prominent than in foveal cones. A weaker and slower adaptation in foveal cones helps maintain a higher sensitivity for a longer duration which may be well-suited for maximizing the collection of high-acuity information at the fovea during gaze fixation between rapid eye movements.

Evaluation of Optical Tracking to Distinguish Surgeon Experience During Endoscopic Stone Surgery.

Introduction and Objectives: Optical tracking (OT) has shown potential in assessing surgical skill but has yet to be evaluated for endoscopic urologic surgery. We sought to evaluate the potential for OT to distinguish expert and trainee surgeons during flexible ureteroscopy (fURS) for kidney stone treatment in both simulated and live surgical settings. Methods: We performed OT analysis of six surgeons performing stone localization during fURS in two settings. In the first setting, surgeons were tasked with fiducial localization in three separate kidney phantoms during fURS. In the second setting, surgeons performed stone localization via fURS in five separate patients. Surgeons were categorized as "expert" (n = 3, endourologist, average case volume of >100 fURS per year) or trainee (n = 3, trainee, <100 fURS per year). OT metrics were recorded for both settings using the Microsoft HoloLens 2© as the surgeons viewed the surgical monitor during fURS. Standard OT metrics of experts and trainees were compared, and included: area of eye gaze movement, gaze distance traveled, number of gaze fixation points, percentage of gaze fixation dwell time, and number of saccades. Results: In the simulated setting, the average time for stone localization was greater for trainees compared to experts (318 seconds vs 52 seconds, p < 0.01). Additionally, the mean area of eye gaze movements with area of interest (AOI) was greater for trainees compared to experts (1430 cm2 vs 1060 cm2, p < 0.01). The total gaze distance traveled was also greater for trainees compared to experts (1480 cm vs 730 cm, p < 0.01). In the live surgical setting, average time for stone localization was similar for trainees and experts (74 seconds vs 51 seconds, p = 0.05). The total area of eye gaze movements in AOI was greater for trainees compared to experts (700 cm2 vs 30 cm2, p < 0.01). Additionally, the total gaze distance traveled was greater for trainees compared to experts (14,000 cm vs 680 cm, p < 0.01). This suggests more varied and less point specific concentration on the surgical screen by trainees. There was no difference in percentage of gaze fixation dwell time and number of saccades between experts and trainees in either setting. Conclusions: OT analysis can objectively distinguish surgical experience between experts and trainee surgeons performing fURS in both simulated and live surgical settings. These findings may play a role in future surgical training and skills assessment.

A rare case of peripheral facial paralysis associated with meningococcal meningitis - case report

Introduction. Meningococcal meningitis is a severe form of bacterial meningitis caused by the bacterium Neisseria meningitidis (N. meningitidis). It is a medical emergency and requires prompt treatment to prevent severe complications or death. Peripheral facial paralysis is one of the rare complications that can occur in this condition. Aim. This paper aimed to draw attention to the possibility of an unexpected complication in a child with meningococcal meningitis, which requires prompt clinical and paraclinical management. Materials and methods. We present the case of a 2-year and 8-month-old female patient who, in the context of meningococcal meningitis, develops peripheral facial paralysis, a very rare complication, especially in the pediatric population. Results. The patient initially presented with clinical and paraclinical signs of a respiratory viral infection. However, in a febrile context, she has two generalized tonic-clonic paroxysmal episodes, characterized by gaze fixation, each lasting 2-3 minutes, followed by spontaneous recovery. Laboratory tests revealed neutrophilia, anemia, and elevated inflammatory markers, while the cranio-cerebral CT scan showed no structural changes. Blood cultures were also collected, and treatment was initiated with third-generation cephalosporin antibiotics, along with supportive and symptomatic therapy. The following day, the patient exhibited signs of right-sided peripheral facial paralysis, and intravenous corticosteroid therapy was added to the treatment. Approximately 24 hours after admission, the blood culture tested positive for gram-negative cocci, suggesting meningococcal meningitis. A cerebral MRI was performed, revealing changes indicative of acute meningoencephalitis. The clinical and paraclinical course was slowly favorable, with a slight persistence of facial asymmetry and intermittent ataxic syndrome. Conclusions. Meningococcal meningitis remains a relevant pathology in the pediatric population, able of causing severe complications that can result in long-term disability for the patient. Prompt treatment is crucial when this condition is suspected.

Investigating the links between sustained attention, gaze fixation patterns, and face identity discrimination performance

Investigating the links between sustained attention, gaze fixation patterns, and face identity discrimination performance

Characterization of Gaze Metrics and Visual Search Pattern Among Glaucoma Patients While Viewing Real-World Images.

We quantified and compared the gaze metrics during target-oriented visual search tasks between glaucoma and healthy controls. On the basis of a mathematical concept we showed that due to glaucoma, focal search becomes prominent over global search. Visual search (VS) which is essential for target identification and navigation is significantly impacted by glaucoma. VS metrics can be influenced by differences in cultural exposure or coping strategies, leading to varying VS patterns. This study aimed to explore and label the pattern of VS based on gaze metrics quantified using eye-tracking technology. Twenty-seven glaucoma subjects and 30 healthy controls [median age 51 (14) and 54 (19)y, respectively] underwent a VS experiment during which they had to identify specific targets from real-world images. Eye movements were recorded using a remote eye-tracker and gaze metrics-fixation count (FC), fixation duration (FD), saccade amplitude (SA), and VS time (VST) were computed and compared between the study groups. A Z -score-based coefficient " K " was derived to label the search patterns as global ( K ≤ - 0.1: short FD with long SA), focal ( K ≥+0.1: long FD with short SA), or a combination ( K between ±0.1). Similar to other ethnicities, Indian glaucoma subjects also exhibited statistically significantly increased FC, FD, and VST ( P =0.01). Healthy controls presented a comparable proportion of focal (47%) and global (42%) search patterns while glaucoma subjects exhibited predominantly focal (56%) than global search patterns (26%, P =0.008). This study suggests that glaucoma subjects perform more focal searches during active gaze scanning. This change in viewing behavior reflects underlying compensatory strategies adapted for coping with their visual impairments. These search patterns can be influenced by factors such as saliency which requires further investigation.

Positional End-Point Nystagmus in Patients with Diagnosis of Acute Unilateral Vestibulopathy.

Recently, end-point nystagmus, traditionally observed in an upright position, has been identified in the Dix-Hallpike position among healthy subjects, suggesting a physiological origin.However, its characteristics in individuals with vestibular hypofunction remain unexplored. To elucidate the impact of vestibular hypofunction on the characteristics of positional end-point nystagmus. Thirty-one patients diagnosed with acute unilateral vestibulopathy according to Bárány Society criteria were selected. A video head impulse test was conducted in all participants, followed by McClure and Dix-Hallpike maneuvers with and without gaze fixation, and with the initial position of the eye in the straight-ahead position or in the horizontal end-point position. Nystagmus direction, sense, latency, slow-phase velocity, and duration were recorded. The relationship between these characteristics and video head impulse test values was analyzed. Positional end-point nystagmus was observed in 92.6% of subjects with vestibular hypofunction, significantly more than in healthy individuals. Nystagmus direction varied depending on the performed positional test and on the vestibulo-ocular reflex gains. Gaze occlusion and the initial horizontal end-point position increased its frequency. Vestibular hypofunction influences the manifestation of positional end-point nystagmus. Recognizing this nystagmus can aid in resolving diagnostic uncertainties and preventing the misdiagnosis of benign paroxysmal positional vertigo in subjects with acute unilateral vestibulopathy.

Impact of Socio-Demographic Attributes and Mutual Gaze of Virtual Humans on Users' Visual Attention and Collision Avoidance in VR.

This study investigated the extent that the non-verbal behaviors of virtual humans (VHs) and their socio-demographic attributes altered users' collision avoidance behaviors in Virtual Reality (VR). Users interacted with VHs representing different levels of ethnicities and gender, exhibiting different conditions of physical movement, and gaze behaviors. The VHs were depicted in three major ethnic conditions namely Asian, Caucasian, and Black. The physical movement states of the VHs were either static in the path of the user or walking toward the user in the opposite direction. The non-verbal gaze behavior of the VHs was either direct gaze or averted gaze. We used an HTC Vive tracking system to track users' performing real walking while we collected objective measures (i,e., continuous gaze, fixation gaze, clearance distance, and travel length), and subjective variables (i.e., game experiences and social presence). The results showed that the ethnicity of the VHs significantly impacted the gaze behavior of the users, and the gender of the VHs affected the user avoidance movement and their reciprocal gaze behavior. Our results revealed that users' physical movement, gaze behaviors, and collision avoidance were moderated by the VHs' perceived ethnicity, gender, and gaze behaviors. Understanding the impact of the socio-demographics attributes of VHs and their gaze behavior on users' collision avoidance is critical for applications in which users are navigating through virtual traffic, crowd, and other inter-personal simulations.

Acute effects of exercise on gaze fixation and affective response inhibition in children with autism spectrum disorder: A randomized cross-over study.

Children with autism spectrum disorder (ASD) show impairments in response inhibition, especially in socio-emotional contexts. A single aerobic exercise session has the potential to temporarily reduce such impairments as findings from neurotypical children support acute benefits of this exercise type for inhibitory control and emotion recognition. In children with ASD, we therefore aimed to investigate the effects of an aerobic exercise bout on response inhibition in an emotional Go/NoGo task and gaze fixation as possible mechanism underlying changes in performance. Using a cross-over design, 29 patients completed a 20-min aerobic exercise bout at moderate intensity on a cycling ergometer and a control condition in a randomized order. An emotional Go/NoGo task was administered before and after both experimental conditions. Eye-tracking was performed during the cognitive task to assess the duration of gaze fixation of eyes and mouth parts of faces expressing happy or sad emotions. The results support no beneficial effect of exercise on performance on the emotional Go/NoGo task. Instead, patients showed a greater decrease in accuracy on Go trials displaying happy faces in the exercise compared to the control condition. This change was associated with a more pronounced decrease in the fixation duration of the eyes for faces expressing either happy or sad emotions. In conclusion, while a single session of moderately intense aerobic exercise does not affect response inhibition, it temporarily aggravates ASD-specific deficits in the processing of and response to facial emotions.

Evaluating the Link between Visual Attention Bias and Emotion Dysregulation of Young Children

The ability to regulate emotions is vital to successful social interactions. This study explores whether visual attention bias is associated with emotion dysregulation (ED) in early childhood. Parental reports of child ED (Child Behaviour Checklist (CBCL) and Temper Tantrum Scale) were examined in relation to child visual attention bias whilst viewing emotional faces. Results indicated that the level of eye gaze fixation towards emotional images and faces was associated with ED when social function (measured with the Social Responsiveness Scale), gender, age, and attention problems (measured from the CBCL subscale), were adjusted. The modifying effect on visual attention bias was evaluated using interaction analysis in the generalized linear model. The level of visual attention bias, indicated by the proportion of eye gaze fixation time on areas of interest (AOIs) in images displaying unpleasant emotions (such as anger), was inversely associated with the level of externalising problem behaviours (p = .014). Additionally, the association of eye gaze fixation time for AOIs displaying negative emotional cues with the level of externalising problem behaviours varied by age (p = .04), with younger children (aged < 70 months) demonstrating a stronger association than older children (aged ≥\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\ge$$\\end{document} 70 months). Findings suggest that young children with greater ED symptoms look less at unpleasant emotional cues. However, this relationship is attenuated as children become older. Further research to identify objective biomarkers that incorporate eye-tracking tasks may support prediction of ED-related mental health issues in the early years.

Tests of abnormal gaze behavior increase the accuracy of mild cognitive impairment assessments

Tests to detect mild cognitive impairment (MCI) should have high sensitivity and accuracy. Previously, we reported on a cognitive composition test (CCT) that we developed to detect MCI. In this study, we compared gaze behavior parameters, namely, gaze fixation duration and gaze-shift frequency, during the CCT in participants with MCI and healthy controls (HC) to determine whether these parameters would accurately detect MCI in older adults. Participants performed CCT-A, -B, and -C tasks with varying difficulty levels while wearing eye-tracking devices. Performance time, gaze fixation duration, and gaze-shift frequency were analyzed. Receiver operating characteristic curve analysis was performed to assess the identification accuracy. The MCI group was significantly slower in completing the CCT-C task and had a higher gaze-shift frequency into both the sample object space and workspace than the HC group. Gaze fixation duration in the sample object space increased in the MCI group as the CCT became difficult. Our findings indicated that combining the CCT with performance time and gaze pattern improved the accuracy of distinguishing between individuals with and without MCI and that patients with MCI have abnormal gaze behavior during cognitive tasks. Therefore, evaluation of gaze parameters may improve the accuracy of identifying patients with MCI.

Regulation of negative emotions through directed attention in high-trait-anxious women: Evidence from event-related potentials and eye-tracking

Abnormal emotional responses in high-trait-anxious (HTA) individuals may be related to the use of emotion regulation strategies. Directed attention is a substrategy of attention deployment, which has been proven to be effective in regulating individual negative emotions. The present study investigated whether HTA women can effectively utilize directed attention to decrease negative emotions. Two studies were conducted using the same directed attention paradigm, with one focusing on event-related potentials (ERPs) and the other utilizing eye-tracking techniques. Participants viewed negative and neutral pictures and rated their negative emotions experienced during viewing. During directed attention, attention was directed towards highly arousing aspects, less arousing aspects of negative pictures, or less arousing aspects of neutral pictures. In study 1, late positive potentials (LPP) were recorded in 26 HTA and 24 low-trait-anxious (LTA) women. In study 2, the latency of first fixation, the proportion of gaze duration and fixations in the specific area were recorded in 27 HTA and 23 LTA women. Both the HTA and LTA groups revealed a decrease in negative emotional ratings and LPP amplitudes when their attention was directed towards the less arousing aspects of negative pictures. Furthermore, in this condition, the HTA group had a shorter latency of first fixation on highly arousing aspects and a higher proportion of gaze duration on less arousing aspects of negative pictures compared to the LTA group. These results indicate that when confronted with negative pictures, HTA women are able to regulate their emotional responses through directed attention, which may be accompanied by attentional vigilance and avoidance tendencies.

Aging Delays Completion of Head Rotation Cycles in Continuous Gaze Stabilization Exercises despite Putative Healthy Vestibular Function

Introduction: Aging is associated with loss of balance, with falls being one of the leading causes of death among the elderly in the USA. Gaze stabilization exercises (GSE) improve balance control in vestibular populations and could be useful to prevent falls in healthy individuals. However, the extent to which aging affects head kinematics in GSE is unknown. Methods: Forty-eight younger (n = 25, 24 ± 6 years, 60% female) and older (n = 23, 66 ± 5 years, 56% female) adults completed six 30-s GSE. Participants were asked to maintain gaze fixation on a stationary target while continuously performing head movements in pitch (e.g., vertical) and yaw (e.g., horizontal) directions. The visual target was placed on the wall 1 m or 2 m away or handheld at arm’s length. Head kinematics were recorded with an inertial measurement unit placed on the back of the participants’ head. Results: Older adults took significantly more time (e.g., delay) to complete cycles of head rotation in both pitch and yaw compared to younger participants across all GSE. Such delay was further increased during yaw head rotation while fixating gaze of the 1 m target. The average peak velocity (APV) and average angular displacement (AAD), however, were equivalent between groups in all GSE. Conclusion: Aging leads to the maintenance of head rotation APV and AAD at the expense of delayed cycles of head rotation, suggesting an age-dependent prioritization strategy (e.g., adapt duration first, range second) during continuous head movements. The distance of the visual target and head movement direction influenced elderly performance and should be considered when prescribing GSE to older populations.

Saccades and Microsaccades Coupling During Free-Throw Shots in Basketball Players.

We investigated the role of saccades and microsaccades when different levels of basketball players were engaged in an ecological free-throw condition. All participants made more correct than incorrect shoots, with a movement time initiation shorter in amateurs than in near-expert groups. Near-experts had more stable gaze fixation than amateurs, with higher microsaccade rate and duration and lower peak velocity. Amateurs showed higher saccade rate, peak velocity, and amplitude than near-experts. The temporal sequence of near-experts' microsaccade rate increased after the saccade peak; on the contrary, in amateurs, the saccade peak is shown after the decrement in microsaccade rates. The spatiotemporal characteristics of microsaccades and saccades may reflect an optimal sampling method by which the brain discretely acquires visual information and can differentiate between participants who use a fixation before the critical movement time and participants who move their eyes to catch more visual cues to make decisions.

Object Motion Manipulation and time perception in virtual reality

This paper presents a novel approach to altering how time is perceived in Virtual Reality (VR). It involves manipulating the speed and pattern of motion in objects associated with timekeeping, both directly (such as clocks) and indirectly (like pendulums). Objects influencing our perception of time are called ‘zeitgebers‘; for instance, observing a clock or pendulum tends to affect how we perceive the passage of time. The speed of motion of their internal parts (clock hands or pendulum rings) is explicitly or implicitly related to the perception of time. However, the perceptual effects of accelerating or decelerating the speed of a virtual clock or pendulum in VR is still an open question. We hypothesize that the acceleration of their internal motion will accelerate the passage of time and that the irregularity of the orbit pendulum’s motion will amplify this effect. We anticipate that the irregular movements of the pendulum will lower boredom and heighten attention, thereby making time seem to pass more quickly. Therefore, we conducted an experiment with 32 participants, exposing them to two types of virtual zeitgebers exhibiting both regular and irregular motions. These were a virtual clock and an orbit pendulum, each operating at slow, normal, and fast speeds. Our results revealed that time passed by faster when participants observed virtual zeitgebers in the fast speed condition than in the slow speed condition. The orbit pendulum significantly accelerated the perceived passage of time compared to the clock. We believe that the irregular motion requires a higher degree of attention, which is confirmed by the significantly longer gaze fixations of the participants. These findings are crucial for time perception manipulation in VR, offering potential for innovative treatments for conditions like depression and improving wellbeing. Yet, further clinical research is needed to confirm these applications.

Changes in saccadic intrusions over time as an objective biomarker to follow ALS disease progression

Objective: Saccadic Intrusions (SIs) are abnormal eye movements during gaze fixation. Studies have indicated the clinical relevance of SIs, especially of square wave jerks (SWJ) in ALS. We used a software-based platform to extract SIs as a part of an interventional drug trial. The objective was to examine SIs’ change over time as a potential biomarker of ALS disease progression. Methods: 28 ALS patients (61.95 ± 8.6 years) were assessed with the revised ALS Functional Rating Scale (ALSFRS-R) and with an oculometric test. Changes of SIs over time and correlations with ALSFRS-R and its bulbar subscale were calculated. A power calculation was conducted to understand the practical implications of results. Results: A significant increase of SWJ over trial duration was observed, with an increase in frequency (mean rise of 0.14 ± 0.28, p < 0.01), amplitude (0.001 ± 0.0016 degrees, p < 0.005), overall duration of SWJ (0.13 ± 0.25, in %, p < 0.01), and in their relative part out of all intrusions (0.18 ± 0.32, in %, p < 0.005). Negative correlations were found with the bulbar subscale (R=-0.43, −0.41, −0.39 and −0.47, respectively, p < 0.001). The required sample size for observing a 40% reduction in bulbar aspects when using the oculometric test (α = 0.05 and β = 0.8), was found to be 150 patients per arm, compared with 200 patients using the bulbar subscale. Conclusions: Evaluation of saccadic intrusions during fixation was able to detect disease progression over time, correlated with ALSFRS-R bulbar subscale. Eye movements can potentially serve as an objective biomarker in ALS clinical trials and reduce the required sample size to show clinical effect of therapies.