Investigating eye movement acquisition and analysis technologies as a causal factor in differential prevalence of crossed and uncrossed fixation disparity during reading and dot scanning

Kirkby, Julie A.; Blythe, Hazel I.; Drieghe, Denis; Benson, Valerie; Liversedge, Simon Paul

doi:10.3758/s13428-012-0301-2

Cited by 20 publications

(42 citation statements)

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“…Before that, binocularity in reading was largely of interest to researchers claiming that poor binocular coordination might contribute to an explanation of dyslexia (e.g., Stein & Fowler, 1985). It emerged that binocular fixations are often not conjoint in nonreading tasks involving vergence (e.g., Cornell, MacDougall, Predebon, & Curthoys, 2003;Enright, 1998), and it further became clear that this disparity between the two eyes' fixation points extended to reading on a two-dimensional screen (Blythe et al, 2006;Jainta, Hoormann, Kloke, & Jaschinski, 2010;Juhasz, Liversedge, White, & Rayner, 2006;Kirkby, Blythe, Drieghe, Benson, & Liversedge, 2013;Kliegl, Nuthmann, & Engbert, 2006;Nuthmann & Kliegl, 2009;Shillcock, Roberts, Kreiner, & Obregón, 2010; see Kirkby, Webster, Blythe, & Liversedge, 2008, for a review of binocular coordination during reading and nonreading tasks). The two eyes frequently do not fixate on exactly the same point in a line of text; sometimes the left eye may fixate to the left of the right eye, which has been termed an uncrossed fixation disparity, or to the right, a crossed 1 fixation disparity.…”

Section: Binocular Coordinationmentioning

confidence: 97%

A binocular moving window technique to study the roles of the two eyes in reading

2014

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Section: Binocular Coordinationmentioning

confidence: 97%

A binocular moving window technique to study the roles of the two eyes in reading

2014

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“…In the studies by Liversedge et al (2006) and Kirby et al (2013), texts were presented bright on dark background, while in the study of Nuthmann and Kliegl (2009) texts were presented dark on bright background. Hence, the brightness of text might be an important factor influencing binocular coordination; a factor which had been already suggested by Kirkby et al (2013). If this factor has an effect, then the data suggest that reading bright text on dark background leads to vergence points behind the surface whereas reading dark text on bright background leads to a vergence point in front of the surface.…”

Section: Introductionmentioning

confidence: 74%

“…The data were then treated as in the methods described in Liversedge et al (2006) and Kirkby et al (2013): prior to analyses, data were cleaned from fixations lasting less than 80 ms or more than 1200 ms. For the remaining fixations, disparity was computed. Fixations with a disparity deviating more than two standard deviations from the individual mean were excluded.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, they compared the results produced by different eye trackers (SR Research EyeLink 1000 versus Fourward Technologies Inc. DPI binocular eye-tracking systems) during reading and dot scanning. For both trackers, as described in Liversedge et al (2006), also Kirkby et al (2013) observed a majority of uncrossed fixations. Hence, clear evidence for the origins of the opposite fixation disparities in reading is still missing.…”

Section: Introductionmentioning

confidence: 99%

“…DOI: 10.1515/prolas-2017 eyelashes...) were already mentioned as possible sources of variation in other studies (Nyström et al 2013). Kirkby et al (2013) investigated the hypothesis that one potential source for the contradictory findings may be related to different devices used to collect the data as well as the different methods used for analysis. Therefore, they compared the results produced by different eye trackers (SR Research EyeLink 1000 versus Fourward Technologies Inc. DPI binocular eye-tracking systems) during reading and dot scanning.…”

Section: Introductionmentioning

confidence: 99%

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Binocular Coordination in Reading When Changing Background Brightness

Köpsel

Huckauf²

2017

Proceedings of the Latvian Academy of Sciences. Section B. Natural, Exact, and Applied Sciences.

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INTRODUCTIONWhen we look, we fixate on an object of interest with both eyes. The process of aligning both focus points is referred to as binocular coordination, the result of this process is termed vergence. That is, a vergence point is defined as the position where both lines of sight meet. Understanding the alignment of both lines of sight is important also for the understanding of binocular vision, that is, the motor coordination of the eyes as well as the perceptual coordination like, for example, in image fusion. In visual tasks, vergence points are expected to occur where an image is depicted. Therefore, when presenting images on a screen, the fixation location of both eyes is measured on the screen. The resulting difference between fixation locations of both eyes is referred to as fixation disparity. That is, fixation disparity is the difference between the two lines of sight at a given distance, which informs about the spatial accuracy of aligning both lines of sight.Binocular coordination is performed also in seemingly two-dimensional tasks like, for example, in reading. This raises the question of whether two eyes are better than one, as Radach and Heller (1999) put it. With regard to fixation disparity in reading, there are contradictory results. Liversedge et al. (2006) reported that about half of the fixations accompanying reading are unaligned. The authors characterised these fixations as crossed or uncrossed, depending on their disparity: fixations were counted as crossed when the right eye fixated more than one character left of the left eye, and as uncrossed when the right eye fixated more than one character right of the left eye. Expressed as vergence, crossed fixations were described as a vergence point spatially in front of the screen, and uncrossed fixations as a vergence point behind the screen. Liversedge et al. (2006) found more uncrossed fixation disparities than crossed ones, that is, a mean vergence point behind the screen.In contrast, a dominance of crossed fixations and hence, vergence points, which are typically in front of the screen, was reported by Nuthmann and Kliegl (2009). With regard to binocular coordination, one might wonder how image fusion can take place on the basis of such huge amounts of not aligned fixations. In order to understand binocular visual functioning, it is therefore important to distinguish systematic variations of fixation alignments from random variability.There were already various reasons suggested as potentially being responsible for the differences in the findings of Nuthmann and Kliegl (2009) as compared to : differing eye-trackers, calibration procedures, viewing distances and also letter sizes. The former used a chin rest, the latter a bite bar, and participants had to read in different languages (German vs. English). These differences and several more (e.g., glasses, contact lenses, eye colour, PROCEEDINGS OF THE LATVIAN ACADEMY OF SCIENCES. Section B, Vol. 71 (2017)

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Vergence responses to vertical binocular disparity during lexical identification

et al. 2015

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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.

show abstract

Investigating eye movement acquisition and analysis technologies as a causal factor in differential prevalence of crossed and uncrossed fixation disparity during reading and dot scanning

Cited by 20 publications

References 20 publications

A binocular moving window technique to study the roles of the two eyes in reading

A binocular moving window technique to study the roles of the two eyes in reading

Binocular Coordination in Reading When Changing Background Brightness

Vergence responses to vertical binocular disparity during lexical identification

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