Binocular Coordination During Reading and Non-Reading Tasks

School of Psychology, University of Southampton, Southampton, United Kingdom.
Psychological Bulletin (Impact Factor: 14.76). 10/2008; 134(5):742-63. DOI: 10.1037/a0012979
Source: PubMed


The goal of this review is to evaluate the literature on binocular coordination during reading and non-reading tasks in adult, child, and dyslexic populations. The review begins with a description of the basic characteristics of eye movements during reading. Then, reading and non-reading studies investigating binocular coordination are evaluated. Areas of future research in the field are identified and discussed. Finally, some general conclusions are made regarding binocular coordination. The review demonstrates that findings from traditionally independent areas of research are largely consistent and complementary. Throughout the review, theoretical and methodological commonalities are identified and clarified in order to advance current understanding of this fundamental aspect of human visual processing.

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Available from: Julie A Kirkby, Oct 10, 2015
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    • "To summarise, during reading, the visual system is primarily faced with horizontal disparities, which might be the reason why research in written language processing has focused mainly on horizontal binocular coordination (Blythe, Liversedge, & Findlay, 2010; see Kirkby et al., 2008 for review). Indeed, few studies so far have systematically investigated misalignments in reading in other dimensions, a limitation to the comprehensive understanding of binocular coordination that the current work aimed to address. "
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    ABSTRACT: Humans typically make use of both eyes during reading, which necessitates precise binocular coordination in order to achieve a unified perceptual representation of written text. A number of studies have explored the magnitude and effects of naturally occurring and induced horizontal fixation disparity during reading and non-reading tasks. However, the literature concerning the processing of disparities in different dimensions, particularly in the context of reading, is considerably limited. We therefore investigated vertical vergence in response to stereoscopically presented linguistic stimuli with varying levels of vertical offset. A lexical decision task was used to explore the ability of participants to fuse binocular image disparity in the vertical direction during word identification. Additionally, a lexical frequency manipulation explored the potential interplay between visual fusion processes and linguistic processes. Results indicated that no significant motor fusional responses were made in the vertical dimension (all p-values > .11), though that did not hinder successful lexical identification. In contrast, horizontal vergence movements were consistently observed on all fixations in the absence of a horizontal disparity manipulation. These findings add to the growing understanding of binocularity and its role in written language processing, and fit neatly with previous literature regarding binocular coordination in non-reading tasks.
    Vision Research 11/2014; 106. DOI:10.1016/j.visres.2014.10.034 · 1.82 Impact Factor
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    • ". This effect is also consistent with the literature showing that, during fixation, vergence movements occur that reduce the magnitude of fixation disparity (Blythe et al., 2006; Jainta et al., 2010; Kirkby et al., 2010; Liversedge, White, et al., 2006; Nuthmann & Kliegl, 2009; see Kirkby et al., 2008, for a review). The interaction between eyetracker and sample point was also significant, F "
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    ABSTRACT: Previous studies examining binocular coordination during reading have reported conflicting results in terms of the nature of disparity (e.g. Kliegl, Nuthmann, & Engbert (Journal of Experimental Psychology General 135:12-35, 2006); Liversedge, White, Findlay, & Rayner (Vision Research 46:2363-2374, 2006). One potential cause of this inconsistency is differences in acquisition devices and associated analysis technologies. We tested this by directly comparing binocular eye movement recordings made using SR Research EyeLink 1000 and the Fourward Technologies Inc. DPI binocular eye-tracking systems. Participants read sentences or scanned horizontal rows of dot strings; for each participant, half the data were recorded with the EyeLink, and the other half with the DPIs. The viewing conditions in both testing laboratories were set to be very similar. Monocular calibrations were used. The majority of fixations recorded using either system were aligned, although data from the EyeLink system showed greater disparity magnitudes. Critically, for unaligned fixations, the data from both systems showed a majority of uncrossed fixations. These results suggest that variability in previous reports of binocular fixation alignment is attributable to the specific viewing conditions associated with a particular experiment (variables such as luminance and viewing distance), rather than acquisition and analysis software and hardware.
    Behavior Research Methods 01/2013; 45(3). DOI:10.3758/s13428-012-0301-2 · 2.12 Impact Factor
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    • "There is an evidence of sensorimotor deficits in dyslexics, including auditory processing [45], visual processing [46] and motor (cerebellar) control [47] impairments . If these deficits include ocular motor problems is still an open question [48]. Much research has been reported on the visual function of dyslexic children [18–21, 29, 49], little is known about the visual parameters in young dyslexic adults. "
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    ABSTRACT: Dyslexia is a worldwide disorder in children and adults. The visual characteristics of dyslexics has been studied with variable results. One area of interest is fixation disparity (FD). This is a measure of alignment of the oculomotor system during binocular fusion. A graphical plot of the FD as it changes as a function of induced prisms before the eyes results in a forced vergence fixation disparity curve (FDC). The associated phoria is defined as the prism needed to return the FD to the ortho position. We performed FD evaluations and compared FDC characteristics with a group of 50 subjects: 25 dyslexic adults and 25 typically reading adults. The comparisons suggest that exo FD and the absolute amount of associated phoria tend to be higher in dyslexic adults. Moreover, they experience more instability of FD compared to the controls. They also have more limited convergence range and total vergence range. Both instability in motor responses and reduced vergence ranges indicate that binocular instability is likely to occur in dyslexic adults.
    Optica Applicata 01/2012; 42(4):805-820. DOI:10.5277/oa120412 · 0.46 Impact Factor
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