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Vision Research

Ignace T C Hooge, Roy S Hessels, Marcus Nyström
A binocular eye tracker needs to be accurate to enable the determination of vergence, distance to the binocular fixation point and fixation disparity. These measures are useful in e.g. the research fields of visual perception, binocular control in reading and attention in 3D. Are binocular pupil-based video eye trackers accurate enough to produce meaningful binocular measures? Recent research revealed potentially large idiosyncratic systematic errors due to pupil-size changes. With a top of the line eye tracker (SR Research EyeLink 1000 plus), we investigated whether the pupil-size artefact in the separate eyes may cause the eye tracker to report apparent vergence when the eyeballs do not rotate...
January 11, 2019: Vision Research
Alessio Facchin, Silvio Maffioletti, Marialuisa Martelli, Roberta Daini
Eye charts are typically optimized to assess visual acuity (VA) with constant and controlled spacing, while close-to-acuity crowding limits letter identification in the normal fovea when adjacent letters are closely spaced. Here we developed a clinical tool that enables the assessment of acuity with different levels of crowding. In a cross-sectional study, we examined the developmental trajectories with our newly devised Milan Eye Chart (MEC). A total of 252 children of 1st, 3rd and 5th grade were assessed with the MEC using SLOAN letter optotypes with 100%, 50%, 25% and 12...
January 9, 2019: Vision Research
Aleksandra Zharikova, Sergei Gepshtein, Cees van Leeuwen
No abstract text is available yet for this article.
January 9, 2019: Vision Research
Alisa Braun, Timothy D Sweeny
While object perception may feel instantaneous, it is an iterative process in which information is accumulated until ambiguity about identity and location is resolved. In theory, awareness of an object should depend on how efficiently this process occurs. Therefore, objects with inherently weak visual representations should be more susceptible to perceptual disruption. We tested this hypothesis by examining the perception of aspect ratio, a 2D feature of shapes with anisotropic representation (circular shapes are less robustly represented than elongated shapes in high-level visual areas)...
January 8, 2019: Vision Research
Laveniya Kugathasan, Marita Partanen, Violet Chu, Christopher Lyons, Deborah Giaschi
Previous studies have reported compromised reading ability in children with amblyopia. Standardized psychoeducational test norms have not been used; therefore, the practical consequences of poor reading ability, such as eligibility for reading supports at school, have not been assessed. Furthermore, several studies have used atypical reading conditions such as monocular or distant viewing. It is also not clear how amblyopia treatment impacts reading ability. Thus, the goal of this study was to use standardized tests to compare binocular reading performance in children treated for amblyopia to that of a large normative sample, as well as to the types of control groups used in previous studies...
January 8, 2019: Vision Research
Jean-Baptiste Bernard, Eric Castet
Letters and words across the visual field can be difficult to identify due to limiting visual factors such as acuity, crowding and position uncertainty. Here, we show that when human readers identify words presented at foveal and para-foveal locations, they act like theoretical observers making optimal use of letter identity and letter position information independently extracted from each letter after an unavoidable and non-optimal letter recognition guess. The novelty of our approach is that we carefully considered foveal and parafoveal letter identity and position uncertainties by measuring crowded letter recognition performance in five subjects without any word context influence...
January 7, 2019: Vision Research
Adam J Parker, Timothy J Slattery, Julie A Kirkby
During reading, eye movement patterns differ between children and adults. Children make more fixations that are longer in duration and make shorter saccades. Return-sweeps are saccadic eye movements that move a reader's fixation to a new line of text. Return-sweeps move fixation further than intra-line saccades and often undershoot their target. This necessitates a corrective saccade to bring fixation closer to the start of the line. There have been few empirical investigations of return-sweep saccades in adults, and even fewer in children...
January 6, 2019: Vision Research
Jonathan D Victor, Syed M Rizvi, Mary M Conte
While luminance, contrast, orientation, and terminators are well-established features that are extracted in early visual processing and support the parsing of an image into its component regions, the role of more complex features, such as closure and convexity, is less clear. A main barrier in understanding the roles of such features is that manipulating their occurrence typically entails changes in the occurrence of more elementary features as well. To address this problem, we developed a set of synthetic visual textures, constructed by replacing the binary coloring of standard maximum-entropy textures with tokens (tiles) containing curved or angled elements...
January 3, 2019: Vision Research
Gennady Erlikhman, Sion Gutentag, Christopher D Blair, Gideon P Caplovitz
We present a series of novel observations about interactions between flicker and motion that lead to three distinct perceptual effects. We use the term flicker to describe alternating changes in a stimulus' luminance or color (i.e. a circle that flickers from black to white and visa-versa). When objects flicker, three distinct phenomena can be observed: (1) Flicker Induced Motion (FLIM) in which a single, stationary object, appears to move when it flickers at certain rates; (2) Flicker Induced Motion Suppression (FLIMS) in which a moving object appears to be stationary when it flickers at certain rates, and (3) Flicker-Induced Induced-Motion (FLIIM) in which moving objects that are flickering induce another flickering stationary object to appear to move...
January 3, 2019: Vision Research
Gantz Liat, Sousou Muli, Gavrilov Valerie, Bedell Harold E
Two case studies in the literature report on patients with infantile nystagmus (IN) who preferred to read text that is oriented vertically rather than horizontally. The current study systematically evaluated the effect of text orientation (-60 to +90 deg with respect to horizontal) on reading speed in nine individuals with IN associated with albinism at Hadassah Academic College (HAC), seven individuals with IN at the University of Houston (UH), and a total of 17 normal control observers. Observers at HAC read 40-character passages of Hebrew text from standardized 2nd grade level reading material and observers at UH read MNRead acuity chart sentences...
December 24, 2018: Vision Research
Natacha Stolowy, Aurélie Calabrèse, Lauren Sauvan, Carlos Aguilar, Thomas François, Núria Gala, Frédéric Matonti, Eric Castet
People with central field loss (CFL) use peripheral vision to identify words. Eccentric vision provides ambiguous visual inputs to the processes leading to lexical access. Our purpose was to explore the hypothesis that this ambiguity leads to strong influences of inferential processes, our prediction being that increasing word frequency would decrease word reading time. Individuals with bilateral CFL induced by macular diseases read French sentences displayed with a self-paced reading method. Reading time of the last word of each sentence (target word) was recorded...
December 17, 2018: Vision Research
Aparna Raghuram, David G Hunter, Sowjanya Gowrisankaran, Deborah P Waber
Although there are many anecdotal reports of children with developmental dyslexia complaining of vision symptoms when reading, empirical studies are lacking. The primary aim of the present study was to document self-reported vision-related symptoms in children with developmental dyslexia and typically reading peers. We also explored whether vision symptoms were correlated with sensorimotor measures of vergence, accommodation and ocular motor tracking skills. Using a prospective group comparison observational design, we assessed 28 children with developmental dyslexia (DD) and 33 typically reading children (TR) 7- 11 years of age...
December 4, 2018: Vision Research
Gunnar Schmidtmann, Ingo Fruend
The visual system is exposed to a vast number of shapes and objects. Yet, human object recognition is effortless, fast and largely independent of naturally occurring transformations such as position and scale. The precise mechanisms of shape encoding are still largely unknown. Radial frequency (RF) patterns are a special class of closed contours defined by modulation of a circle's radius. These patterns have been frequently and successfully used as stimuli in vision science to investigate aspects of shape processing...
November 26, 2018: Vision Research
Shui'Er Han, Raphael Lukaszewski, David Alais
Continuous flash suppression (CFS) is a technique in which presenting one eye with a dynamic Mondrian sequence prevents a low-contrast target in the other eye from being perceived for many seconds. Frequently used to study unconscious visual processing, CFS bears many similarities with binocular rivalry (BR), another popular dichoptic stimulation technique. It is therefore puzzling that the effect of mask size and contrast seem to differ between CFS and BR. To resolve this discrepancy, we conducted a systematic investigation on the effects of mask size and contrast in CFS...
November 24, 2018: Vision Research
Ilka Claus, Katharina Frey, Tobias Hönle, Robert Brüning, Andreas Reichenbach, Mike Francke, Robert Brunner
To further extent our understanding of aquatic vision, we introduce a complete optical model of a goldfish eye, which comprises all important optical parameters for the first time. Especially a spherical gradient index structure for the crystalline lens was included, thus allowing a detailed analysis of image quality, regarding spot size, and wavelength dependent aberration. The simulation results show, that our realistic eye model generates a sufficient image quality, with a spot radius of 4.9μm which is below the inter cone distance of 5...
November 23, 2018: Vision Research
Vivek Labhishetty, Arijit Chakraborty, William R Bobier
School aged children with progressive myopia show large accommodative lags to blur only cue and is suggestive of a large depth of focus (DOF). While DOF measures are lacking in this age group, their blur detection and discrimination capacities appear to be similar to their non-myopic peers. Accordingly, the current study quantified DOF and blur detection ability in progressive myopic children showing large accommodative lags compared to their non-myopic peers and adults. Blur sensitivity measures were taken from 12 children (8-13years, 6 myopes and 6 emmetropes) and 6 adults (20-35years)...
November 22, 2018: Vision Research
Claudio de'Sperati, Ian M Thornton
Accurate motion prediction is fundamental for survival. How does this reconcile with the well-known speed underestimation of low-contrast stimuli? Here we asked whether this contrast-dependent perceptual bias is retained in motion prediction under two different saccadic planning conditions: making a saccade to an occluded moving target, and real-time gaze interaction with multiple moving targets. In a first experiment, observers made a saccade to the mentally extrapolated position of a moving target (imagery condition)...
November 21, 2018: Vision Research
Saki Takao, Colin W G Clifford, Katsumi Watanabe
A stimulus surrounded by smaller/larger stimuli appears larger/smaller (Ebbinghaus illusion). We examined whether the Ebbinghaus illusion would depend on the retinal or perceived size of the surrounding stimuli. The flash-lag effect, where a flashed stimulus perceptually lags moving stimuli, was used to dissociate the retinal from perceived size of the surrounding stimuli. Two sets of four surrounding disks changed their size smoothly: one with larger disks shrinking, the other with smaller disks expanding...
November 21, 2018: Vision Research
Trent Koessler, Harold Hill
Ocular accommodation potentially provides information about depth but there is little evidence that this information is used by the human visual system. We use the hollow-face illusion, an illusion of depth reversal, to investigate whether accommodation is linked to perceived depth. In Experiment 1 accommodation, like vergence, was in front of the physical surface of the mask when the mask was upright and people reported experiencing the illusion. Accommodation to the illusory face did not differ significantly from accommodation to the physically convex back surface of the same mask...
November 20, 2018: Vision Research
Ekaterina Koshmanova, Tadamasa Sawada
The perception of a pair of contours in a retinal image cannot be understood simply by adding up the perceptions of the individual contours, especially when they form a perpendicular junction, or are parallel to one another. It is the relationship among the contours that determines what is perceived. Note that it is hard to actually compare the perception of such configurations quantitatively. We managed to do this by testing the perception of such configurations in three psychophysical experiments in which the perception was characterized by measuring the orientation threshold of a single contour...
November 20, 2018: Vision Research
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