Purpose : While microsaccades during fixation are highly correlated in both eyes, the literature is less coherent regarding drifts (Otero-Millan et al, 2014). If drifts show uncorrelated components, the positions of the images of a fixated target on the retina are no longer (mirror)-symmetrical. Symmetrical corrective microsaccades should then no longer be optimal for both eyes. To better understand this question, we studied interocular correlations in ocular drifts. Methods : We built a high resolution binocular eye tracker with two USB3 infrared monochrome cameras having 640x480 pixel resolution and 320 Hz sampling rate (TheImagingSource, Model DMK33UX174). Both inputs were merged into one video buffer to synchronize binocular tracking, cutting the sampling rate down to 160 Hz. We developed software to precisely track both pupil centers and first Purkinje image centers generated by a field of IR LEDs (angular noise level ,2 arcmin). After an automated self-calibration procedure, fixational eye ...
Fixation changes in glaucoma are generally overlooked, as they are not strikingly evident as in macular diseases. Fundus perimetry might give additional insights into this aspect, along with traditional perimetric measures. In this work we propose a novel method to quantify glaucomatous changes in fixation features as detected by fundus perimetry and relate them to the extent of glaucomatous damage. We retrospectively analysed fixation data from 320 people (200 normal subjects and 120 with glaucoma) from the Preferred Retinal Locus (PRL) detection of a Compass perimeter. Fixation stability was measured as Bivariate Contour Ellipse Area (BCEA), and using two novel metrics: (1) Mean Euclidean Distance (MED) from the Preferred Retinal Locus, and (2) Sequential Euclidean Distance (SED) of sequential fixation locations. These measures were designed to capture the spread of fixation points, and the frequency of position changes during fixation, respectively. In the age corrected analysis, SED was
A more fruitful way to uncover a useful function for microsaccades would be to choose tasks in which shifts of attention between small details (small enough to fit within the central half degree of the retina) would be expected to be crucial. Winterson and Collewijn (1976) measured eye movements of naïve subjects who were asked to aim and shoot a rifle (no bullets) or thread a needle. During the interval of about 2-4 seconds when they performed these tasks, microsaccade rate was never greater than their baseline rate during steady fixation (2/s) and in fact dropped to about 0.5/s during the final portions of the trials. Bridgeman and Palca (1980) obtained a similar result in a comparable task that required a high acuity visual judgment without a directly related motor activity. Specifically, subjects had to judge whether the tip of a moving horizontally oriented "thread" would have ended above or below the tip of a stationary, vertical "needle". Like Winterson and Collewijn (1976), Bridgeman ...
Fixation is a common characteristic in the behavior of an autistic child. The child may be fixated on a book, a picture, a person, maps, music, numbers, or a movie. Whatever the fixation, the high functioning autistic child will become a resident expert on the subject. They will memorize and will be able to regurgitate […]
One further possibility is that childrens unstable fixation and their lower sensitivities are both symptoms of some more global immaturity, such as a general lack of attentiveness. This could be assessed in future by adding explicit catch trials to the test protocol in order to assess childrens false-negative (lapse) rates and false-positive rates (trigger errors).39 Previous work by Tschopp and colleagues40 has shown that lapse rates measured in this manner are strong predictors of childrens thresholds on standard automated perimetry; and on this basis, it seems plausible that such lapses may also explain some or all of childrens deficits in MP. A second/additional possibility is that childrens reduced sensitivities were a direct consequence of their reduced fixation stability. Substantial reductions in visual sensitivity are known to occur during eye movements,41,42 and children made more and larger eye movements than adults (e.g., due to "searching" behaviors, physiological nystagmus, or ...
Monkeys were trained to perform the DPX task (a validated AX-CPT variant) similar to tasks used to measure deficits in executive control in patients (Jones et al., 2010) (see Fig. 1). Each trial a sequence of two dot patterns was presented (a cue followed by a probe; see Fig. 1C) separated by a delay. At the start of each trial, monkeys directed their gaze at the fixation cross presented at the center of the display for a period of 0.5 s. They were required to maintain gaze fixated within 3.3° of the central fixation target throughout the trial (if eye position moved outside this window, the trial aborted). After the initial fixation period, the cue (orange dots) was presented for 1 s, followed by a 1 s delay period, after which the probe (white dots) was presented for 0.5 s (see Fig. 1A). The intertrial interval (from the offset of the probe to the onset of the following cue, including the 0.5 s fixation period) was 1.86 s. Total trial length, from the onset of the cue of one trial to the ...
In Experiment 2, we addressed this third component. We studied the prediction power of a very simple gaze map and offered insights toward building more predictive gaze-augmented saliency models. We discovered that four challenges need to be addressed before making a general model: (a) How to adjust the parameters of the cone? Some parameters that constrain a gaze map include width of the cone, angular uncertainty, and effective length from the center to focus energy (attentional span). Ideally, one would want to only bias the object(s) that the actor is looking at in the scene. If one modulates everything along the cone, then background unattended objects falling on the cone will be modulated as well (which is not efficient). In Experiment 2, we employed a uniform map. The results of Experiment 3 can be used to calibrate this simple map. For example, a better than uniformly distributing activation would emphasize more at the center line (bisector angle) of the cone and decay it using a Gaussian ...
To determine how subjects allocate gaze to plan their route through the obstacles, we developed the following two measures: spatial gaze distance and spatial-temporal gaze distance. For both measures, we used the positions of the obstacle and the end gates to divide the path into eight segments (S1-S8; see Fig. 2A). Each segment is the same length, expect for the first one (S1) because of the subjects start position and the last one (S8) that represents the end region of the path; these unequal segment lengths are accounted for in the calculation of each of the two gaze distance measures. The anterior-posterior position of the subjects chest marker determines which segment they are located in. For both measures, we determined which segment(s) subjects fixated relative to their location for the first five segments they walked through. We excluded the last three segments because the subjects have walked past the fourth obstacle by this point and gaze begins to deviate from the walking path and ...
Research focusing on perceptual-cognitive skill in sport is abundant. However, the existing qualitative syntheses of this research lack the quantitative detail necessary to determine the magnitude of differences between groups of varying levels of skills, thereby limiting the theoretical and practical contribution of this body of literature. We present a meta-analytic review focusing on perceptual-cognitive skill in sport (N = 42 studies, 388 effect sizes) with the primary aim of quantifying expertise differences. Effects were calculated for a variety of dependent measures (i.e., response accuracy, response time, number of visual fixations, visual fixation duration, and quiet eye period) using point-biserial correlation. Results indicated that experts are better than nonexperts in picking up perceptual cues, as revealed by measures of response accuracy and response time. Systematic differences in visual search behaviors were also observed, with experts using fewer fixations of longer duration, ...
Sitting by the window,I lay my gaze on the vain clusters of clouds gathered together as if to celebrate the pain in my heart. Does this pa ...
Task transparency in learning by demonstration : gaze, pointing, and dialog. . Biblioteca virtual para leer y descargar libros, documentos, trabajos y tesis universitarias en PDF. Material universiario, documentación y tareas realizadas por universitarios en nuestra biblioteca. Para descargar gratis y para leer online.
Écrins National Park, nature reserve located in the départements of Hautes-Alpes and Isère, southeastern France. The park, which was created in 1973, occupies 226,694 acres (91,740 hectares) and is the second largest national park in France. It encompasses the Alpine peaks of Barre des Écrins
There was a lot of past effort to figure out what fixational eye movements contribute to our vision," adds lead author Ziad Hafed, Ph.D., Sloan-Swartz Fellow in the Systems Neurobiology Laboratory, "but nobody had looked at the neural mechanism that generates these movements. Without such knowledge, one could only go so far in evaluating microsaccades significance and why they actually exist." Wondering whether the command center responsible for generating fixational eye movements resides within the same brain structure that is in charge of initiating and directing large voluntary eye movements, Hafed decided to measure neural activity in the superior colliculus before and during microsaccades. He not only discovered that the superior colliculus is an integral part of the neural mechanism that controls microsaccades, but he also found that individual neurons in the superior colliculus are highly specific about which particular microsaccade directions and amplitudes they command-whether they be, ...
DOI /s z Clustering of Gaze During Dynamic Scene Viewing is Predicted by Motion Parag K. Mital Tim J. Smith Robin L. Hill John M. Henderson Received: 23 April 2010 / Accepted: 5 October
In a companion paper, we reported that the goldfish oculomotor neural integrator could be trained to instability or leak by rotating the visual surround with a velocity proportional to +/- horizontal eye position, respectively. Here we analyze changes in the firing rate behavior of neurons in area I in the caudal brainstem, a central component of the oculomotor neural integrator. Persistent firing could be detuned to instability and leak, respectively, along with fixation behavior. Prolonged training could reduce the time constant of persistent firing of some cells by more than an order of magnitude, to |1 s. Normal visual feedback gradually retuned persistent firing of integrator neurons toward stability, along with fixation behavior. In animals with unstable fixations, approximately half of the eye position-related cells had upward or unstable firing rate drift. In animals with leaky fixations, two-thirds of the eye position-related cells showed leaky firing drift. The remaining eye position-related
TY - JOUR. T1 - Decreased fixation stability of the preferred retinal location in juvenile macular degeneration. AU - Bethlehem, R.A.. AU - Dumoulin, S.O.. AU - Dalmaijer, E.S.. AU - Smit, M.. AU - Berendschot, T.T.. AU - Nijboer, T.C.. AU - van der Stigchel, S.. PY - 2014/6/17. Y1 - 2014/6/17. N2 - Macular degeneration is the main cause for diminished visual acuity in the elderly. The juvenile form of macular degeneration has equally detrimental consequences on foveal vision. To compensate for loss of foveal vision most patients with macular degeneration adopt an eccentric preferred retinal location that takes over tasks normally performed by the healthy fovea. It is unclear however, whether the preferred retinal locus also develops properties typical for foveal vision. Here, we investigated whether the fixation characteristics of the preferred retinal locus resemble those of the healthy fovea. For this purpose, we used the fixation-offset paradigm and tracked eye-position using a high spatial ...
Purpose: To investigate whether glaucoma produces measurable changes in eye movements.. Methods: Fifteen glaucoma patients with asymmetric vision loss (difference in mean deviation [MD] , 6 dB between eyes) were asked to monocularly view 120 images of natural scenes, presented sequentially on a computer monitor. Each image was viewed twice-once each with the better and worse eye. Patients eye movements were recorded with an Eyelink 1000 eye-tracker. Eye-movement parameters were computed and compared within participants (better eye versus worse eye). These parameters included a novel measure: saccadic reversal rate (SRR), as well as more traditional metrics such as saccade amplitude, fixation counts, fixation duration, and spread of fixation locations (bivariate contour ellipse area [BCEA]). In addition, the associations of these parameters with clinical measures of vision were investigated.. Results: In the worse eye, saccade ...
The fundamental role of the visual system is to guide behavior in natural environments. In order to optimize information transmission many animals have evolved a non-homogeneous retina and serially sample visual scenes by saccadic eye movements. Such eye movements, however, introduce high-speed retinal motion and decouple external and internal reference frames. Until now, these processes have only been studied with unnatural stimuli, eye movement behavior, and tasks. These experiments confound retinotopic and geotopic coordinate systems and may probe a non-representative functional range. Here we develop a real-time gaze-contingent display with precise spatio-temporal control over high-definition natural movies. In an active condition, human observers freely watched nature documentaries and indicated the location of periodic narrow-band contrast increments relative to their gaze position. In a passive condition under central fixation, the same retinal input was replayed to each observer by ...
Alteration of a fixation or peripheral stimulus displayed on a computer-driven display allows a human subject to maintain extended visual fixation upon the resulting dynamic stimulus. The fixation is presented upon the display and the stimulus is altered to allow resensitization of the subjects retina, thereby allowing prolonged visual fixation upon the resulting dynamic target. A dynamic stimulus may utilize a frequency doubling illusion.
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This study analyzed how an unexpected, transient, passive movement of the head during saccades that were initiated while the head was fixed, affects the trajectory of saccades. We showed that the accuracy of the saccade was not altered by the head perturbation. A system based on separate eye and head controllers would not maintain accuracy, because the eye controller would have no way to assess the amount of the gaze trajectory that had been affected by a perturbation with a VOR gain ,1. Thus, our results imply that the brain combines the action of the VOR (whatever its gain) and a feedback mechanism for gaze. We also showed that the saccade trajectory is affected more by the perturbation for larger saccade amplitudes, and when the onset of the head perturbation was close to the onset of the saccade. Finally, we showed that the modulation of the saccade trajectory was insensitive to the latency of the saccade with respect to the target presentation.. In our experiment, we created a passive ...
A vertebral fixation device includes a fixation main body, two fixation rods and a rotatable clamping block. The fixation main body is made up of a fixation base having a fixation hole. Located respectively at both ends of the fixation base is a fixation block having an arcuate surface capable of holding one of the two fixation rods in conjunction with one of two arcuate recesses of the rotatable clamping block. The rotatable clamping block is provided at the bottom thereof with a retaining projection engageable securely with the fixation hole of the fixation main body.
Lucid dream science has come a long way in the last few decides, culminating in recent research using brainwave, bloodflow and eye movement data.
To determine whether chip components are properly mounted on a printed circuit board, two sets of slit light beams for projecting slit line images in mutually perpendicular directions are alternately made incident thereon diagonally from above. Edges of the mounted chip components produce discontinuities in the projected slit beam image patterns such that the positions, sizes, orientations, etc. of individual mounted components can be calculated from image data obtained from viewing positions above the circuit board by a camera or the like. Since it can be easily ascertained how the slit line image pattern should appear if proper components are properly mounted, an analysis of the calculated data can indicate whether the chip components are properly mounted on the tested printed circuit board.
Find the right height and most comfortable viewing position for your monitor with a PC monitor stand. Proper ergonomic monitor stand elevation helps reduce neck and eye strain.
A comprehensive evaluation of the patients visual motor systems ability to track and change visual fixation, maintain and accurately change focus, and to maintain the efficient use of two eyes functioning together. Problems in these areas may contribute to inefficient reading and a poor attention span.. ...
If you are a high school junior or senior just getting started with the college search, visiting us during this event is a great option to get an introductory look at Luther. Make sure to bring your parents, since we have activities for them, too.. The registration deadline for the October 17 Preview Day is Tuesday, October 15.. Preview Day Schedule. ...
We offer a great selection of fixation tools for paediatric vision testing including medical pen torches, Lang cubes and Kay Picture fixation sticks.
Reading back at several of my previous posts, I realized that I sounded more like a version of myself rather than my whole self. It was like I had amplified parts of myself and excluded other parts. Yeah...I dont want to do that. I want to find out more about who I am, who I want to be, and project that out into the world. When I look at the past ten years, I realize that the times when things seemed to "fall into place" were those times when I was being the most authentic. But like when you are a kid and finally master a task, only to screw it up when you holler at your mom to have her come watch...I think that once I realized that the Universe had cast its gaze on me I have always immediately tripped over myself and face planted on the sidewalk ...
The ZB MED preprint Viewer preVIEW includes all COVID-19, corona, SARS-CoV-2 related preprints from medRxiv, bioRxiv, arXiv, Preprints.org and ChemRxiv.
The ZB MED preprint Viewer preVIEW includes all COVID-19, corona, SARS-CoV-2 related preprints from medRxiv, bioRxiv, arXiv, Preprints.org and ChemRxiv.
Sitting by the window,I lay my gaze on the vain clusters of clouds gathered together as if to celebrate the pain in my heart. Does this pa ...
Pardon me for the goodu question but, I still dun get the depth on view preview function. :dunno: I understand that wat it does is to allow me to see how much the apperture opens (i think). But except for making the viewfinder darker (for a smaller apperture) how does it allow me to gauge how much depth of field will appear in my shot? I mean I cant really tell if the DOP is going to be shallower or deeper. What / how am I to use it effectively? Danke....
The latest build of Windows 10 Technical Preview 2 has apparently hit the expected quality bar and, as a result, is now available as in ISO download form.
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The next expansion, Mean Streets of Gadgetzan, has been announced, and many of the cards have been spoiled already. This preview discusses the neutral...
TheBodyPRO.com will be providing on-the-ground reporting and coverage for IAS 2015. But before we get there, heres part one of our preview on the ...
http://msn.foxsports.com/nfl/story/BrownsSteelers-Preview-53094727 Browns-Steelers Preview UPDATED DEC 26, 2012 9:35 PM ET
Ive finished up my preview of Iwills new E7505 based DP533 motherboard. Its quite a nice board with some unique features. Heres a teaser for you: I know that quite a few of you are very interested...
The European Union said it won't back down from plans to cancel public buying of surplus maize, a system that has encouraged some farmers to grow for subsidies rather than responding to real demand.
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Facial expression and gaze direction play an important role in social communication. Previous research has demonstrated the perception of anger is enhanced by direct gaze, whereas it is unclear whether perception of fear is enhanced by averted gaze. In addition, previous research has shown the anxiety affects the processing of facial expression and gaze direction, but hasnt measured or controlled for depression. As a result, firm conclusions cannot be made regarding the impact of individual differences in anxiety and depression on perceptions of face expressions and gaze direction. The current study attempted to reexamine the effect of the anxiety level on the processing of facial expressions and gaze direction by matching participants on depression scores. A reliable psychophysical index of the range of eye gaze angles judged as being directed at oneself (the Cone of Direct Gaze: CoDG) was used as the dependent variable in this study. Participants were stratified into high/low trait anxiety groups and
Abstract: BACKGROUND: The broad autism phenotype includes subclinical autistic characteristics found to have a higher prevalence in unaffected family members of individuals with autism. These characteristics primarily affect the social aspects of language, communication, and human interaction. The current research focuses on possible neurobehavioral characteristics associated with the broad autism phenotype. METHODS: We used a face-processing task associated with atypical patterns of gaze fixation and brain function in autism while collecting brain functional magnetic resonance imaging (fMRI) and eye tracking in unaffected siblings of individuals with autism. RESULTS: We found robust differences in gaze fixation and brain function in response to images of human faces in unaffected siblings compared with typically developing control individuals. The siblings gaze fixations and brain activation patterns during the face processing task were similar to that of the autism group and showed decreased ...
To do: Fixate your gaze on the red dot, while paying attention to the solid grey circle (called an "artificial scotoma". After a few seconds of steady fixation, the solid circle will fill in with the surrounding dynamic noise. Eye movements or blinks will cause the grey circle to reappear.. To notice: After the dynamic noise disappears (in 20 seconds), a powerful texture after-image takes the place originally occupied by the solid grey circle. This after-image may be dynamic: the so-called Twinkle effect (Ramachandran and Gregory, 1991) or static (Spillmann and Kurtenbach, 1992).. Dynamic filling-in occurs when eye movements are lacking or reduced. Our laboratory has showed that microsaccades (small involuntary eye movements that occur when we attempt to fixate) counteract visual fading and filling-in during visual fixation (Troncoso, Macknik and Martinez-Conde, 2008).. ...
This thesis is about our peripheral vision. Peripheral vision is poor compared to central vision, due to both neural and optical factors. The optical factors include astigmatism, defocus and higher order aberrations consisting mainly of coma. Neurally, the density of ganglion cells decreases towards the periphery, which limits the sampling density. The questions that this thesis attempts to answer are how much and under which circumstances correction of optical errors can improve peripheral vision. For this, an adaptive optics system has been constructed with a wavefront sensor and a deformable mirror working in closed loop to perform real-time correction of optical errors. To investigate vision, psychophysical routines utilizing Bayesian methods have been evaluated and modified for peripheral vision to handle the presence of aliasing, fixation instability and rapid fatigue.. We found that correcting both refractive errors and higher order aberrations improved peripheral low-contrast resolution ...
Even if all external circumstances are kept equal, the oculomotor system shows intra-individual variability over time, affecting measures such as microsaccade rate, blink rate, pupil size, and gaze position. Recently, some of these measures have been associated with ADHD on a between-subject level. However, it remains unclear to what extent these measures constitute stable individual traits. In the current study, we investigate the intra-individual reliability of these oculomotor features. Combining results over three experiments (,100 healthy participants), we found evidence for intra-individual reliability over different time points (repeatability) as well as over different conditions (generalization). Furthermore, we correlated oculomotor variability with self-assessed ADHD tendencies, mind wandering, and impulsivity, and found evidence against such correlations. As such, the oculomotor system shows reliable intra-individual reliability, but its use for distinguishing self-assessed individual ...
A fundamental task performed by many visual systems is to distinguish apparent motion caused by eye movements from real motion occurring within the environment. During saccadic eye movements, this task is achieved by inhibitory signals of central and retinal origin that suppress the output of motion-detecting neurons. To investigate the retinally-generated component of this suppression, we used a computational model of a locust looming-detecting pathway that experiences saccadic suppression. This model received input from the camera of a mobile robot that performed simple saccade-like movements, allowing the models response to simplified real stimuli to be tested. Retinally-generated saccadic suppression resulted from two inhibitory mechanisms within the looming-detectors input architecture. One mechanism fed inhibition forward through the network, inhibiting the looming-detectors initial response to movement. The second spread inhibition laterally within the network, suppressing the ...
Prolonged Eye Gaze (usually for a few seconds or more), coupled with a breath focus with multiple members of an audience, one person at a time, is one of the primary ways for speakers to access the state of Relational Presence with their audience, forming the cornerstone of Speaking Circles practice.. More generally in human behavior, eye gaze is critical for processing social signals. We use eye gaze, including focused eye contact and inspection of facial expression, to predict anothers intention and mental state.1 Infants begin to use eye gaze socially at around four months of age. An infants eye contact with their caregiver may influence the development of typical social gaze behaviors1 and also directly reflect the infants attachment and comfort with their mother.2 The amount of eye contact between a mother and her newborn may also correlate with her sensitivity or capacity for attunement.3 Shared eye gaze thus underlies and is formative in the development of social ...
Why does the painting appear to move at all? The phenomenon is known as illusory motion, and most scientists attribute it to a flaw in our visual cortex. But according to the Arizona researchers new study, the motion is actually a result of microsaccades - unconscious eye movements that occur spontaneously whenever we focus our eyes. The researchers arrived at their conclusion after mounting tiny infared cameras on a helmet and tracking the eyeballs of people confronted with "Enigma." Oddly, microsaccade rates increased right before the motion began and all but disappeared before the painting went still. The illusions real, it seems, but in a twist that Alan Watts and Carlos Castaneda anticipated, its an illusion that lies within us all." ...
In the background of evolution, gaze following is one of the oldest manifestations of leadership. Three-month-old babies, for example, already follow the eye movements of their parents. Psychologists at VU University Amsterdam ...