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Scientific Reports Jan 2022Pupillometry has become a standard measure for assessing arousal state. However, environmental factors such as luminance, a primary dictator of pupillary responses,...
Pupillometry has become a standard measure for assessing arousal state. However, environmental factors such as luminance, a primary dictator of pupillary responses, often vary across studies. To what degree does luminance interact with arousal-driven pupillary changes? Here, we parametrically assessed luminance-driven pupillary responses across a wide-range of luminances, while concurrently manipulating cognitive arousal using auditory math problems of varying difficulty. At the group-level, our results revealed that the modulatory effect of cognitive arousal on pupil size interacts multiplicatively with luminance, with the largest effects occurring at low and mid-luminances. However, at the level of individuals, there were qualitatively distinct individual differences in the modulatory effect of cognitive arousal on luminance-driven pupillary responses. Our findings suggest that pupillometry as a measure for assessing arousal requires more careful consideration: there are ranges of luminance levels that are more ideal in observing pupillary differences between arousal conditions than others.
Topics: Acoustic Stimulation; Adolescent; Adult; Arousal; Cognition; Female; Fixation, Ocular; Heart Rate; Humans; Light; Male; Photic Stimulation; Pupil; Screen Time; Vision, Ocular; Young Adult
PubMed: 35082319
DOI: 10.1038/s41598-022-05280-1 -
Neuroscience Letters Mar 2020This study investigated the effects of wearing a head-mounted eye tracker on upright balance during different visual tasks. Twenty five young adults stood upright on a...
This study investigated the effects of wearing a head-mounted eye tracker on upright balance during different visual tasks. Twenty five young adults stood upright on a force plate while performing the visual tasks of fixation, horizontal saccades, and eyes closed, during eighteen trials wearing or not a head-mounted eye tracker. While wearing the eye tracker, participants showed a reduction in mean sway amplitude and velocity of the CoP in the AP and ML directions and more regular CoP fluctuations, in the ML axis in all conditions. Higher mean sway amplitude and velocity of CoP were observed during eyes closed than fixation and saccades. Moreover, horizontal saccades reduced mean sway velocity of CoP compared to fixation. Therefore, wearing the eye tracker minimized the body sway of young adults; however, visual task-related effects on postural stability remained unchanged.
Topics: Eye Movements; Eye-Tracking Technology; Female; Fixation, Ocular; Humans; Male; Postural Balance; Wearable Electronic Devices; Young Adult
PubMed: 32088198
DOI: 10.1016/j.neulet.2020.134799 -
Journal of Neurophysiology Dec 2021The influence of internal brain state on behavioral performance is well illustrated by the gap saccade task, in which saccades might be initiated with short latency...
The influence of internal brain state on behavioral performance is well illustrated by the gap saccade task, in which saccades might be initiated with short latency (express saccade) or with long latency (regular saccade) even though the external visual condition is identical. Accumulated evidence has demonstrated that the internal brain state is different before the initiation of an express saccade than a regular saccade. However, the reported origin of the fluctuation of internal brain state is disputed among previous studies, e.g., the fixation disengagement theory versus the oculomotor preparation theory. The present study examined these two theories by analyzing the rate and direction of fixational saccades, i.e., small amplitude saccades during fixation, because they could be modulated by the internal brain state. Since fixation disengagement is not spatially tuned, it might affect the rate but not the direction of fixational saccades. In contrast, oculomotor preparation can contain spatial information for the upcoming saccade and thus affect fixational saccade direction. We found that the different spatiotemporal characteristics of fixational saccades among tasks with different gap durations reveal diverse driving force to change the internal brain state. Under short gap duration (100 ms), fixation disengagement plays a primary role in switching internal brain states. Conversely, oculomotor preparation plays a primary role under medium (200 ms) and long (400 ms) gap durations. These results suggest that both fixation disengagement and oculomotor preparation can change the internal brain state, but their relative contributions are gap-duration dependent. While performing the gap saccade task, the role of fixation disengagement and oculomotor preparation in modulating the internal brain state is gap-duration dependent. Fixation disengagement plays a primary role when gap duration is shorter (100 ms), whereas oculomotor preparation plays a primary role when gap duration is longer (200 ms and 400 ms).
Topics: Animals; Behavior, Animal; Eye-Tracking Technology; Fixation, Ocular; Macaca mulatta; Male; Psychomotor Performance; Saccades; Time Factors
PubMed: 34758281
DOI: 10.1152/jn.00259.2021 -
ENeuro 2022Our eyes are constantly in motion and the various kinds of eye movements are closely linked to many aspects of human cognitive processing. Measuring all possible eye...
Our eyes are constantly in motion and the various kinds of eye movements are closely linked to many aspects of human cognitive processing. Measuring all possible eye movements unobtrusively is not achievable with current methods. Video-based eye-trackers only measure rotational but not translational motion of the eye, require a calibration process relying on the participant's self-report of accurate fixation, and do not work if vision of the eyeball is blocked. Scleral search coils attach physical weight on the eyeball and also do not measure translation. Here, we describe a novel and fully automated method to use real-time magnetic resonance imaging (MRI) for eye tracking. We achieved a temporal resolution sufficient to measure eye rotations and translations as short as those that occur within a blink and behind a closed eyelid. To demonstrate this method, we measured the full extent of the blink-related eye movement for two individuals, suggesting that the eye approaches a holding position during lid closure and can move by as much as 35° in rotation and 2 mm in translation. We also investigated the coordination of gaze shifts with blinks. We found that the gaze shift is tightly coupled in time to the translational blink movement and that blinks can induce significant temporal shifts of the gaze trajectory between left and right eye. Our MR-based Eye Tracking (MREyeTrack) method allows measurement of eye movements in terms of both translation and rotation and enables new opportunities for studying ocular motility and its disorders.
Topics: Biomechanical Phenomena; Blinking; Eye Movements; Eyelids; Fixation, Ocular; Humans; Magnetic Resonance Imaging
PubMed: 34876474
DOI: 10.1523/ENEURO.0357-21.2021 -
The Journal of Physiology Nov 2019Vision plays a crucial role in guiding locomotion in complex environments, but the coordination between gaze and stride is not well understood. The coordination of gaze...
KEY POINTS
Vision plays a crucial role in guiding locomotion in complex environments, but the coordination between gaze and stride is not well understood. The coordination of gaze shifts, fixations, constant gaze and slow gaze with strides in cats walking on different surfaces were examined. It was found that gaze behaviours are coordinated with strides even when walking on a flat surface in the complete darkness, occurring in a sequential order during different phases of the stride. During walking on complex surfaces, gaze behaviours are typically more tightly coordinated with strides, particularly at faster speeds, only slightly shifting in phase. These findings indicate that the coordination of gaze behaviours with strides is not vision-driven, but is a part of the whole body locomotion synergy; the visual environment and locomotor task modulate it. The results may be relevant to developing diagnostic tools and rehabilitation approaches for patients with locomotor deficits.
ABSTRACT
Vision plays a crucial role in guiding locomotion in complex environments. However, the coordination between the gaze and stride is not well understood. We investigated this coordination in cats walking on a flat surface in darkness or light, along a horizontal ladder and on a pathway with small stones. We recorded vertical and horizontal eye movements and 3-D head movement, and calculated where gaze intersected the walkway. The coordination of gaze shifts away from the animal, gaze shifts toward, fixations, constant gaze, and slow gaze with strides was investigated. We found that even during walking on the flat surface in the darkness, all gaze behaviours were coordinated with strides. Gaze shifts and slow gaze toward started in the beginning of each forelimb's swing and ended in its second half. Fixations peaked throughout the beginning and middle of swing. Gaze shifts away began throughout the second half of swing of each forelimb and ended when both forelimbs were in stance. Constant gaze and slow gaze away occurred in the beginning of stance. However, not every behaviour occurred during every stride. Light had a small effect. The ladder and stones typically increased the coordination and caused gaze behaviours to occur 3% earlier in the cycle. At faster speeds, the coordination was often tighter and some gaze behaviours occurred 2-16% later in the cycle. The findings indicate that the coordination of gaze with strides is not vision-driven, but is a part of the whole body locomotion synergy; the visual environment and locomotor task modulate it.
Topics: Animals; Cats; Darkness; Female; Fixation, Ocular; Forelimb; Head Movements; Locomotion; Male; Psychomotor Performance; Vision, Ocular; Walking
PubMed: 31460673
DOI: 10.1113/JP278108 -
Sensors (Basel, Switzerland) Apr 2024In mobile eye-tracking research, the automatic annotation of fixation points is an important yet difficult task, especially in varied and dynamic environments such as...
In mobile eye-tracking research, the automatic annotation of fixation points is an important yet difficult task, especially in varied and dynamic environments such as outdoor urban landscapes. This complexity is increased by the constant movement and dynamic nature of both the observer and their environment in urban spaces. This paper presents a novel approach that integrates the capabilities of two foundation models, YOLOv8 and Mask2Former, as a pipeline to automatically annotate fixation points without requiring additional training or fine-tuning. Our pipeline leverages YOLO's extensive training on the MS COCO dataset for object detection and Mask2Former's training on the Cityscapes dataset for semantic segmentation. This integration not only streamlines the annotation process but also improves accuracy and consistency, ensuring reliable annotations, even in complex scenes with multiple objects side by side or at different depths. Validation through two experiments showcases its efficiency, achieving 89.05% accuracy in a controlled data collection and 81.50% accuracy in a real-world outdoor wayfinding scenario. With an average runtime per frame of 1.61 ± 0.35 s, our approach stands as a robust solution for automatic fixation annotation.
Topics: Humans; Fixation, Ocular; Eye-Tracking Technology; Video Recording; Algorithms; Eye Movements
PubMed: 38732772
DOI: 10.3390/s24092666 -
Ophthalmic & Physiological Optics : the... Mar 2022For normally sighted observers, the centre of the macula-the fovea-provides the sharpest vision and serves as the reference point for the oculomotor system. Typically,... (Review)
Review
For normally sighted observers, the centre of the macula-the fovea-provides the sharpest vision and serves as the reference point for the oculomotor system. Typically, healthy observers have precise oculomotor control and binocular visual performance that is superior to monocular performance. These functions are disturbed in patients with macular disease who lose foveal vision. An adaptation to central vision loss is the development of a preferred retinal locus (PRL) in the functional eccentric retina, which is determined with a fixation task during monocular viewing. Macular disease often affects the two eyes unequally, but its impact on binocular function and fixational control is poorly understood. Given that patients' natural viewing condition is binocular, the aim of this article was to review current research on binocular visual function and fixational oculomotor control in macular disease. Our findings reveal that there is no overall binocular gain across a range of visual functions, although clear evidence exists for subgroups of patients who exhibit binocular summation or binocular inhibition, depending on the clinical characteristics of their two eyes. The monocular PRL of the better eye has different characteristics from that of the worse eye, but during binocular viewing the PRL of the better eye drives fixational control and may serve as the new reference position for the oculomotor system. We conclude that evaluating binocular function in patients with macular disease reveals important clinical aspects that otherwise cannot be determined solely from examining monocular functions, and can lead to better disease management and interventions.
Topics: Fixation, Ocular; Humans; Retinal Diseases; Scotoma; Vision, Binocular; Visual Acuity
PubMed: 34862635
DOI: 10.1111/opo.12925 -
International Journal of Environmental... Oct 2019There are a limited number of studies focusing on the mechanisms explaining why variable practice gives an advantage in a novel situation and constant practice in...
There are a limited number of studies focusing on the mechanisms explaining why variable practice gives an advantage in a novel situation and constant practice in performance in trained conditions. We hypothesized that this may be due to the different gaze behavior that is developed under different conditions. Twenty participants, randomly assigned to two different groups, practiced basketball free throws for three consecutive days, performing 100 throws per day. The constant group ( = 10) practiced at a free throw distance (4.57 m) only. The variable practice group ( = 10) randomly performed 20 shots per five throw distances (3.35, 3.96, 4.57, 5.18, and 5.79 m) on each day, also accumulating 100 shots per day. We analyzed the total gaze fixation duration, a number of fixations, and the average fixation duration on a basketball rim in a pretest and posttest at the 4.57 m distance. We computed a linear mixed model with test (pretest-posttest), group (constant-variable), and test × group interaction in order to analyze the total fixation duration and number of fixations. The average fixation duration was analyzed with a repeated measure two-way ANOVA, with practice conditions as a between-participants factor and test type as a within-participants factor. We found that the total fixation duration increased significantly in the posttest, regardless of the practice conditions ( < 0.001, effect size = 0.504). The number of fixations also increased significantly in the posttest ( = 0.037, effect size = 0.246). The average fixation duration increased in both groups; however, insignificantly. We also did not find any significant differences between groups. Our results suggest that variable and constant practice conditions may lead to the development of similar gaze behavior.
Topics: Adult; Basketball; Female; Fixation, Ocular; Humans; Male; Practice, Psychological; Sports; Young Adult
PubMed: 31614871
DOI: 10.3390/ijerph16203875 -
PloS One 2020Bistable stimuli can give rise to two different interpretations between which our perception will alternate. Recent results showed a strong coupling between eye...
Bistable stimuli can give rise to two different interpretations between which our perception will alternate. Recent results showed a strong coupling between eye movements and reports of perceptual alternations with motion stimuli, which provides useful tools to objectively assess perceptual alternations. However, motion might entrain eye movements, and here we check with a static picture, the Necker cube, whether eye movements and perceptual reports (manual responses) reveal similar or different alternation rates, and similar or different sensitivity to attention manipulations. Using a cluster analysis, ocular temporal windows were defined based on the dynamics of ocular fixations during viewing of the Necker cube and compared to temporal windows extracted from manual responses. Ocular temporal windows were measured also with a control condition, where the physical stimulus presented to viewers alternated between two non-ambiguous versions of the Necker cube. Attention was manipulated by asking subjects to either report spontaneous alternations, focus on one percept, or switch as fast as possible between percepts. The validity of the ocular temporal windows was confirmed by the correspondence between ocular fixations when the physical stimulus changed and when the bistable Necker cube was presented. Ocular movements defined smaller time windows than time windows extracted from manual responses. The number of manual and ocular windows both increased between the spontaneous condition and the switch condition. However, only manual, and not ocular windows, increased in duration in the focus condition. Manual responses involve decisional mechanisms, and they may be decoupled from automatic oscillations between the two percepts, as suggested by the fact that both the number and duration of ocular windows remained stable between the spontaneous and focus conditions. In all, the recording of eye movements provides an objective measure of time windows, and reveals faster perceptual alternations with the Necker cube and less sensitivity to attention manipulations than manual responses.
Topics: Adult; Eye Movements; Female; Fixation, Ocular; Humans; Male; Photic Stimulation; Time Factors
PubMed: 31940327
DOI: 10.1371/journal.pone.0227506 -
PloS One 2019Participants' eye movements (EMs) and EEG signal were simultaneously recorded to examine foveal and parafoveal processing during sentence reading. All the words in the...
Participants' eye movements (EMs) and EEG signal were simultaneously recorded to examine foveal and parafoveal processing during sentence reading. All the words in the sentence were manipulated for inter-word spacing (intact spaces vs. spaces replaced by a random letter) and parafoveal preview (identical preview vs. random letter string preview). We observed disruption for unspaced text and invalid preview conditions in both EMs and fixation-related potentials (FRPs). Unspaced and invalid preview conditions received longer reading times than spaced and valid preview conditions. In addition, the FRP data showed that unspaced previews disrupted reading in earlier time windows of analysis, compared to string preview conditions. Moreover, the effect of parafoveal preview was greater for spaced relative to unspaced conditions, in both EMs and FRPs. These findings replicate well-established preview effects, provide novel insight into the neural correlates of reading with and without inter-word spacing and suggest that spatial selection precedes lexical processing.
Topics: Adolescent; Adult; Attention; Female; Fixation, Ocular; Healthy Volunteers; Humans; Macula Lutea; Male; Pattern Recognition, Visual; Reading; Time Factors; Young Adult
PubMed: 31851679
DOI: 10.1371/journal.pone.0225819