scholarly journals Fixation disparity during reading: Fusion, not suppression

2008 ◽  
Vol 2 (3) ◽  
Author(s):  
Simon P. Liversedge
Keyword(s):  
Visual Processing ◽  
Early Stage ◽  
Visual Representation ◽  
Fixation Disparity ◽  
Binocular Coordination ◽  
Target Words

In this paper I present a brief review of some recent studies my colleagues and I have carried out to investigate binocular coordination during reading. These studies demonstrate that the eyes are often not perfectly aligned during reading, with fixation disparities of approximately one character on average. Both crossed and uncrossed disparities are common and vergence movements during fixations serve to reduce, but not eliminate disparity. Fixation disparity results in different retinal inputs from each eye, yet a single non diplopic visual representation of the text is perceived when we read. A further experiment, with dichoptically presented target words in normally presented sentence frames, showed that a mechanism of fusion rather than suppression operates at an early stage during visual processing. Saccade metrics appear to be computed according to a unified visual representation based on input from both eyes. based on input from both eyes.

Binocular Coordination, Fixation Disparity, and Ocular Dominance

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 128-128 ◽  
Author(s):  
R Radach ◽  
D Heller ◽  
P Wiebories ◽  
W Jaschinski
Keyword(s):  
Visual Processing ◽  
Temporal Dynamics ◽  
Ocular Dominance ◽  
Visual Direction ◽  
Psychophysical Method ◽  
Reliable Estimate ◽  
Letter Detection ◽  
Fixation Disparity ◽  
Saccade Length ◽  
Binocular Coordination

In a series of experiments we have quantified the spatial and temporal dynamics of binocular coordination. Tasks studied ranged from simple scanning and letter detection to complex visual processing in text reading. In all of these paradigms we found similar eye movement characteristics: in 70% to 90% of the observations, the saccade of the abducting eye is larger, relative differences being in the order of 5% to 15% of the amplitude. During the subsequent fixation the disparity is typically reduced by a convergence movement (about 1 deg s−1), which sometimes exceeds the initial saccade amplitude asymmetry. Interestingly, the relative vergence contributions of the eyes depend on saccade length. For progressive 2-letter reading saccades, the left (adducting) eye accounts for only 20% of the total movement as compared to about 70% for 14-letter saccades. Up to now our analysis was limited to relative rather than absolute estimates of fixation disparity. To overcome this restriction, we measured disparity using the psychophysical method of dichoptically presented nonius lines as well as direct infrared pupil-reflection registration of binocular vs monocular fixation. Both measures were independent of target eccentricity (within a range typical for reading) and produced similar subject rank orders (Spearman's \rho=0.75). When we studied vergence movements in a letter detection task using autostereograms with different levels of virtual depth, it became clear that spatiotemporal vergence parameters can be quite asymmetric for both eyes. This led to the question of whether unequal contributions to vergence may be related to ocular dominance. This hypothesis is currently being investigated with a new procedure that provides a reliable estimate of subjective visual direction (the ‘cyclopean eye’) under static viewing conditions.

scholarly journals Do standard optometric measures predict binocular coordination during reading?

2021 ◽  
Vol 13 (6) ◽  
Author(s):  
Joëlle Joss ◽  
Stephanie Jainta
Keyword(s):  
Eye Movements ◽  
Visual Processing ◽  
Fixation Duration ◽  
Dynamic Parameter ◽  
Complex Task ◽  
Test Results ◽  
Regression Analyses ◽  
Fixation Disparity ◽  
Explained Variance ◽  
Binocular Coordination

In reading, binocular eye movements are required for optimal visual processing and thus, in case of asthenopia or reading problems, standard orthoptic and optometric routines check individual binocular vision by a variety of tests. The present study therefore examines the predictive value of such standard measures of heterophoria, accommodative and vergence facility, AC/A-ratio, NPC and symptoms for binocular coordination parameters during reading. Binocular eye movements were recorded (EyeLink II) for 65 volunteers during a typical reading task and linear regression analyses related all parameters of binocular coordination to all above-mentioned optometric measures: while saccade disconjugacy was weakly predicted by vergence facility (15% explained variance), vergence facility, AC/A and symptoms scores predicted vergence drift (31%). Heterophoria, vergence facility and NPC explained 31% of fixation disparity and first fixation duration showed minor relations to symptoms (18%). In sum, we found only weak to moderate relationships, with expected, selective associations: dynamic parameter related to optometric tests addressing vergence dynamics, whereas the static parameter (fixation disparity) related mainly to heterophoria. Most surprisingly, symptoms were only loosely related to vergence drift and fixation duration, reflecting associations to a dynamic aspect of binocular eye movements in reading and potentially non-specific, overall but slight reading deficiency. Thus, the efficiency of optometric tests to predict binocular coordination during reading was low – questioning a simple, straightforward extrapolation of such test results to an overlearned, complex task.

Computing with Self-Excitatory Cliques: A Model and an Application to Hyperacuity-Scale Computation in Visual Cortex

1999 ◽  
Vol 11 (1) ◽  
pp. 21-66 ◽  
Author(s):  
Douglas A. Miller ◽  
Steven W. Zucker
Keyword(s):  
Visual Processing ◽  
Network Architecture ◽  
Early Stage ◽  
Cortical Cell ◽  
Pyramidal Cells ◽  
Direct Calculation ◽  
Formal Theory ◽  
Cortical Cells ◽  
Cell Counts ◽  
Spatiotemporal Response

We present a model of visual computation based on tightly inter-connected cliques of pyramidal cells. It leads to a formal theory of cell assemblies, a specific relationship between correlated firing patterns and abstract functionality, and a direct calculation relating estimates of cortical cell counts to orientation hyperacuity. Our network architecture is unique in that (1) it supports a mode of computation that is both reliable and efficent; (2) the current-spike relations are modeled as an analog dynamical system in which the requisite computations can take place on the time scale required for an early stage of visual processing; and (3) the dynamics are triggered by the spatiotemporal response of cortical cells. This final point could explain why moving stimuli improve vernier sensitivity.

The “Mosaic Stage” in Amodal Completion as Characterized by Magnetoencephalography Responses

2006 ◽  
Vol 18 (8) ◽  
pp. 1394-1405 ◽  
Author(s):  
Gijs Plomp ◽  
Lichan Liu ◽  
Cees van Leeuwen ◽  
Andreas A. Ioannides
Keyword(s):  
Neural Activity ◽  
Visual Processing ◽  
Early Stage ◽  
Amodal Completion ◽  
Peak Latency ◽  
Per Se

We investigated the process of amodal completion in a same-different experiment in which test pairs were preceded by sequences of two figures. The first of these could be congruent to a global or local completion of an occluded part in the second figure, or a mosaic interpretation of it. We recorded and analyzed the magnetoencephalogram for the second figures. Compared to control conditions, in which unrelated primes were shown, occlusion and mosaic primes reduced the peak latency and amplitude of neural activity evoked by the occlusion patterns. Compared to occlusion primes, mosaic ones reduced the latency but increased the amplitude of evoked neural activity. Processes relating to a mosaic interpretation of the occlusion pattern, therefore, can dominate in an early stage of visual processing. The results did not provide evidence for the presence of a functional “mosaic stage” in completion per se, but characterize the mosaic interpretation as a qualitatively special one that can rapidly emerge in visual processing when context favors it.

Priming from the Attentional Blink: A Failure to Extract Visual Tokens but Not Visual Types

1997 ◽  
Vol 8 (2) ◽  
pp. 95-100 ◽  
Author(s):  
Kimron Shapiro ◽  
Jon Driver ◽  
Robert Ward ◽  
Robyn E. Sorensen
Keyword(s):  
Attentional Blink ◽  
Semantic Priming ◽  
Visual Processing ◽  
Visual Representation ◽  
Stimulus Processing ◽  
Visual Events ◽  
Early Visual Processing ◽  
Location Detection ◽  
Subsequent Target ◽  
Initial Target

When people must detect several targets in a very rapid stream of successive visual events at the same location, detection of an initial target induces misses for subsequent targets within a brief period. This attentional blink may serve to prevent interruption of ongoing target processing by temporarily suppressing vision for subsequent stimuli. We examined the level at which the internal blink operates, specifically, whether it prevents early visual processing or prevents quite substantial processing from reaching awareness. Our data support the latter view. We observed priming from missed letter targets, benefiting detection of a subsequent target with the same identity but a different case. In a second study, we observed semantic priming from word targets that were missed during the blink. These results demonstrate that attentional gating within the blink operates only after substantial stimulus processing has already taken place. The results are discussed in terms of two forms of visual representation, namely, types and tokens.

scholarly journals Visual attention spreads broadly but selects information locally

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Satoshi Shioiri ◽  
Hajime Honjyo ◽  
Yoshiyuki Kashiwase ◽  
Kazumichi Matsumiya ◽  
Ichiro Kuriki
Keyword(s):  
Visual Attention ◽  
Spatial Attention ◽  
Visual Processing ◽  
Early Stage ◽  
Event Related Potential ◽  
Spatial Spread ◽  
Local Selection ◽  
Unified View ◽  
Behavioral Evidence ◽  
P3 Component

Abstract Visual attention spreads over a range around the focus as the spotlight metaphor describes. Spatial spread of attentional enhancement and local selection/inhibition are crucial factors determining the profile of the spatial attention. Enhancement and ignorance/suppression are opposite effects of attention, and appeared to be mutually exclusive. Yet, no unified view of the factors has been provided despite their necessity for understanding the functions of spatial attention. This report provides electroencephalographic and behavioral evidence for the attentional spread at an early stage and selection/inhibition at a later stage of visual processing. Steady state visual evoked potential showed broad spatial tuning whereas the P3 component of the event related potential showed local selection or inhibition of the adjacent areas. Based on these results, we propose a two-stage model of spatial attention with broad spread at an early stage and local selection at a later stage.

A Visual Channel Theory Approach to Pilot Performance and Simulator Imagery

1981 ◽  
Vol 25 (1) ◽  
pp. 223-227
Author(s):  
David Regan ◽  
Ronald Kruk ◽  
Ken Beverley ◽  
Tom Longridge
Keyword(s):  
Visual Processing ◽  
Early Stage ◽  
Visual Display ◽  
Flight Simulator ◽  
Theory Approach ◽  
Pilot Performance ◽  
Visual Channel ◽  
Display Design ◽  
Preliminary Study ◽  
Channel Theory

There is a body of experimental evidence supporting the hypothesis that an early stage of visual processing consists of analyzing retinal image information into a number of abstract categories or features, called channels. This paper briefly reviews the channel hypothesis and cites potential implications for flight simulator visual display design. The results of a preliminary study designed to investigate the relationships between channel sensitivity and flight simulator landing performance are presented.

scholarly journals Contribution of Impaired Early-Stage Visual Processing to Working Memory Dysfunction in Adolescents With Schizophrenia

2007 ◽  
Vol 64 (11) ◽  
pp. 1229 ◽  
Author(s):  
Corinna Haenschel ◽  
Robert A. Bittner ◽  
Fabian Haertling ◽  
Anna Rotarska-Jagiela ◽  
Konrad Maurer ◽  
...  
Keyword(s):  
Working Memory ◽  
Visual Processing ◽  
Early Stage ◽  
Memory Dysfunction

Saccade Mechanism Based on Processes for Depth Estimation and Incongruity Detection between Binocular Retinal Images – Analysis of Gazing Positions and Inter-saccade Intervals –

1997 ◽  
Vol 9 (2) ◽  
pp. 111-120
Author(s):  
Hiroaki Kudo ◽  
◽  
Kenya Uomori ◽  
Mitsuho Yamada ◽  
Noboru Ohnishi ◽  
...  
Keyword(s):  
Visual Processing ◽  
Early Stage ◽  
Depth Estimation ◽  
Retinal Images ◽  
Fixation Target ◽  
Occlusion Detection ◽  
Detection Mechanism ◽  
Left And Right

We analyzed binocular gazing positions in the existence of a rim occlusion. When a human gazes at the rim of a textured cylinder, the gazing position shifts from the fixation target, When a human gazes at the rim of a cylinder whose upper-surface is visible, the gazing points are located at the estimated surface's depth. In this paper, to investigate the mechanism changing the gazing point, we analyzed inter-saccade intervals. The result shows that an occlusion detection mechanism exists at an early stage of human visual processing, and the mechanism causes a shorter-interval saccade when incongruity regions between left and right retinal images are detected. We propose a saccade mechanism which includes processes for depth estimation and incongruity detection between binocular retinal images based on relationships between the gazing positions and the results of inter-saccade intervals.

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