Using a dichoptic moving window presentation technique to investigate binocular advantages during reading

Reading comes with a clear binocular advantage, expressed in shorter fixation times and fewer regressions in binocular relative to monocular visual presentations. Little is known, however, about whether the cost associated with monocular viewing derives primarily from the encoding of foveal information or in obtaining a preview benefit from upcoming parafoveal text. In the present sentence reading eye tracking experiment, the authors used a novel dichoptic binocular gaze-contingent moving window technique to selectively manipulate the amount of text made available to the reader both binocularly and monocularly in the fovea and parafovea on a fixation-by-fixation basis. This technique allowed the authors to quantify disruption to reading caused by prevention of binocular fusion during direct fixation of words and parafoveal preprocessing of upcoming text. Sentences were presented (a) binocularly; (b) monocularly; (c) with monocular text to the left of fixation; (d) with monocular text to the right of fixation; or (e) with all words other than the fixated word presented binocularly. A robust binocular advantage occurred for average fixation duration and regressions. Also, while there was a limited cost associated with monocular foveal processing, the restriction of parafoveal processing to monocular information was particularly disruptive. The findings demonstrate the critical importance of a unified binocular input for the efficient preprocessing text to the right of fixation

Methods for reducing visual discomfort in stereoscopic 3D: A review

This work was supported by the EPSRC Grant EP/M01469X/1, “Geometric Evaluation of Stereoscopic Video”

Physiology of the visual control system

Neurophysiological aspects of eye movement in visual control system with differentiation of version and vergenc

Binocular coordination and return-sweep saccades among skilled adult readers

During reading, binocular coordination ensures that a unified perceptual representation of the text is maintained across eye movements. However, slight vergence errors exist. The magnitude of disparity at fixation onset is related to the length of the preceding saccade. Return-sweeps are saccadic eye movements that span a line of text and direct gaze from the end of one line to the start of the next. As these eye movements travel much farther than intraline saccades, increased binocular disparity following a return-sweep is likely. Indeed, increased disparity has been a proposed explanation for longer line-initial fixations. Thus, we sought to address the following questions: Is binocular disparity larger following a return-sweep saccade than it is following an intraline saccade, and is the duration of a line-initial fixation related to binocular disparity and coordination processes? To examine these questions, we recorded binocular eye movements as participants read multiline texts. We report that, following return-sweeps, the magnitude of disparity at fixation onset is increased. However, this increased magnitude of disparity is unrelated to the duration of line-initial fixations. We argue that longer line-initial fixations result from a lack of parafoveal preview for words at the start of the line

Binocular eye movements in humans: from optimal binocularity to strabismus

Binocular vision and stereopsis is one of the major characteristics of frontal eyed species, such as humans. Binocular vision results from the projection of 3D-objects on corresponding area's of the retina's of the two eyes. An individual with. binocular vision perceives one single image of the object containing depth information (binocular vision). The minute differences between the' left and the right image (disparity) ideally give rise to stereoscopic vision. This entity of the binocular system has been used for artificial stereopsis in 3-D pictures and movies. The importance of binocular vision in daily life becomes clear when individuals with optimal binocular coordination are forced to use mostly one eye (e.g. because of an eye infection). Their loss of binocular visual information causes difficulties with simple tasks, like shaking hands. Individuals who have sub-optimal binocularity for a longer period can function very well due to adaptive mechanisms and the use of nonstereoscopic depth cues. Many people are unaware of their slight sub-optimal binocularity which only a stereopsis test reveals. People with low vision in one of their eyes, have less binocularity but the use of both eyes can still be very useful for the detection of large moving objects such as approaching cars. They usually have no impairments in their daily tasks. Individuals with vision in one eye only adapt mainly by making more head movements. With this adaptation they have no difficulties, even with tasks like driving a car

Asymmetrical adaptation of human saccades to anisometropic spectacles

Saccades are the rapid eye movements which enable us to voluntarily shift our gaze from one visual target to another. They serve to bring newly selected visual targets to the fovea of each of the two eyes, which is a small part of the retina with high visual acuity. This accurate, binocular control of saccades requires a high quality of oculomotor coordination. During the course of a lifetime, the various structures involved in the generation and the control of saccades may be subject to change, due to, for example, growth, ageing, disease or injury. These changes will undoubtedly affect saccadic control, and, consequently, jeopardize its quality. To safeguard its proper functioning, the oculomotor system will therefore have to adapt adequately to such changes. As these changes probably take place haphazardly, at different places, with different time-courses and with different degrees of severity, the saccadic subsystem should be capable of adapting specifically to such non-uniform changes. Adaptation of saccades has been described in the literature subsequent to local, physical damage to external eye muscles, as well as to purely visual stimuli (for a review, see Chapter 2). The aim of this thesis was to assess both qualitatively and quantitatively how the sa~cadic subsystem responds to a consistent visual pressure for an asymmetrical adaptation, i.e., adaptation that is different for each of the two eye

Using ocular stability to assess the severity of traumatic brain injuries in children

Almost a million children with mild traumatic brain injury visit the emergency department (mTBI). The overall occurrence is expected to be higher. The heterogeneity of mTBI makes diagnosis challenging. mTBI has been shown to lead to neuroinflammation, axonal degeneration, demyelination, and other pathologies that can have developmental consequences in children. However, there are currently no gold standard objective biomarkers available to aid in the diagnosis of mTBI. Current tools are subject to tester/patient motivation and rely on subjective patient-reported measures. The oculomotor system has been shown to be altered by mTBI. Following an incident, the vast majority of pediatric patients exhibit some change in their normal oculomotor response. Including altered saccades, fixation stability, convergence, and/or smooth pursuits. There are diagnostic tools, such as the Vestibular/Ocular Motor Screening (VOMS), that help with the diagnosis of mTBI. Although this tool is still subjective to patient responses, new technology has emerged that allows the use of the oculomotor system to establish objective biomarkers for the diagnosis of mTBI. The first of these technologies employ infrared (IR) technology to track gross pupil movements in order to assess changes in patients' oculomotor function. The FDA recently approved the first device that uses this technology to diagnose TBI. Eye-tracking technology is becoming more accurate, and previously imperceptible movements can now be captured. Retinal polarization scanning (RPS) is a new technology that can measure micro eye movements. This opens up new avenues for measuring ocular motor dysfunction in mTBI patients and identifies new biomarkers. As technology advances, there is a greater need for the establishment of guidelines and gold standards. Future research should include the development of benchmark metrics and methodologies for comparing the efficacy of such devices and determining their viability in clinic and in the field

Engineering Data Compendium. Human Perception and Performance, Volume 1

The concept underlying the Engineering Data Compendium was the product an R and D program (Integrated Perceptual Information for Designers project) aimed at facilitating the application of basic research findings in human performance to the design of military crew systems. The principal objective was to develop a workable strategy for: (1) identifying and distilling information of potential value to system design from existing research literature, and (2) presenting this technical information in a way that would aid its accessibility, interpretability, and applicability by system designers. The present four volumes of the Engineering Data Compendium represent the first implementation of this strategy. This is Volume 1, which contains sections on Visual Acquisition of Information, Auditory Acquisition of Information, and Acquisition of Information by Other Senses