Lateral facilitation revealed dichoptically for luminance-modulated and contrast-modulated stimuli

Hairol, Mohd Izzuddin; Waugh, Sarah J.

doi:10.1016/j.visres.2010.08.026

Cited by 9 publications

(11 citation statements)

References 56 publications

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“…In addition to luminance and motion stimuli, the visual system is also sensitive to second-order spatial characteristics, such as modulations of contrast (contrast-modulated or CM stimuli) or texture, without a change in mean luminance. These second-order targets require extra stages of processing to be extracted by the visual system above that required for first-order luminance targets, which may occur in cortical units receiving predominantly binocular input (Wong, Levi, & McGraw, 2001Hairol & Waugh, 2010;Chima et al, 2015;Skerswetat, Formankiewicz, & Waugh, 2016). In amblyopia and strabismus, reduced sensitivity to CM stimuli above that found in normal eyes may be expected due to binocular disruption.…”

Section: Introductionmentioning

confidence: 99%

Interocular suppression patterns in binocularly abnormal observers using luminance- and contrast-modulated noise stimuli

2016

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In binocular viewing, images presented to the amblyopic eye are suppressed in the cortex to prevent confusion or diplopia. The present study measures depth and extent of interocular suppression across the central circular 24° visual field in observers with strabismus and microstrabismus. Visual stimuli were concentric rings of alternating polarity, each divided into sectors. Rings were defined by luminance (L), luminance-modulated noise (LM), or contrast-modulated noise (CM). They were viewed binocularly except for the tested ring, which was viewed dichoptically, so that the modulation of one sector presented to the weaker or amblyopic eye was adjusted to perceptually match the surrounding ring presented to the preferred eye. A two alternative forced-choice paradigm combined with a staircase procedure allowed for measurement of the point of subjective equality, or perceptual match. Depth of suppression was calculated as the difference between physical modulations presented to the two eyes at this point. Strabismic participants showed suppression deeper centrally than peripherally, and in one hemifield of the visual field more than the other. Suppression was deeper for L than LM, and CM than LM stimuli. Microstrabismic suppression was weaker than that of strabismics, central for L and LM stimuli, with suppression of CM stimuli being broader, deeper and more in one hemifield. Suppression depth was positively correlated with interocular visual acuity difference and stereoacuity reduction. Clinically, LM stimuli could be used for assessment of deeper amblyopes to assess suppression patterns, while more sensitive detection of mild suppression would be possible using CM stimuli.

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Section: Introductionmentioning

confidence: 99%

Interocular suppression patterns in binocularly abnormal observers using luminance- and contrast-modulated noise stimuli

2016

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“…Steeper psychometric function slopes can also reflect high levels of intrinsic observer uncertainty (as well as stimulus uncertainty) in contrast detection and discrimination tasks, with steeper slopes indicating greater uncertainty. 59 – 63 We suggest that when intrinsic uncertainty is high, small increases in visibility (or size in this acuity task) when compared to a blank screen could lead to larger improvements in performance and steeper psychometric function slopes than if the same increases were introduced when it is low. The stimuli used in the current study were known and constant across age.…”

Section: Discussionmentioning

confidence: 89%

Grouping Effects on Foveal Spatial Interactions in Children

Waugh

Formankiewicz

2020

Invest. Ophthalmol. Vis. Sci.

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Grouping of flankers from the target can modulate crowding in adults. Visual acuity in children is measured clinically using charts with targets and different flankers to enhance spatial interactions. We investigated grouping effects on interactions using visual acuity letters, flanked by contours and letters, in children. METHODS. Visual acuity for isolated and flanked letters was measured in 155 three-to 11-year old children and 32 adults. Flankers were one stroke width from the target and were a box or four bars and black or red letters. Magnitudes of interaction were flanked minus isolated logMAR acuities. Psychometric function slopes were also examined. RESULTS. Magnitudes of interaction by contours did not change significantly with age. They were 0.047 ± 0.014 logMAR more with bars than a box. Interaction from flanking letters reduced with age, adults being not different from 9-to 11-year-olds for black and red letter surrounds. It was weaker by 0.033 ± 0.013 logMAR when a black letter was surrounded by red rather than black letters. Psychometric function slopes for visual acuity were steepest for the youngest children (3-5 years). CONCLUSIONS. For contour and letter flankers, grouping effects on interaction magnitude are age independent. Grouping bars into a box forming a single object reduces magnitude of effect. Grouping letter flankers by color and ungrouping them from the target reduce interaction magnitude by ∼8%, suggesting that luminance-defined form dominates. Differently colored letter flankers of high-luminance contrast on acuity charts could draw attention to the target but retain significant interaction strength.

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“…Ten stimulus pages were created using the equations above, each with a different, random noise pattern. These ten pages were cycled in random order for the duration of the trial to generate dynamic noise to avoid consistent first-order artefacts in second-order stimuli due to pixel clumping that would occur if static noise were used 26,[28][29][30][31] .…”

Section: Methodsmentioning

confidence: 99%

Contrast-modulated stimuli produce more superimposition and predominate perception when competing with comparable luminance-modulated stimuli during interocular grouping

Skerswetat

Formankiewicz

Waugh

2020

Sci Rep

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Interocular grouping (IOG) is a binocular visual function that can arise during multi-stable perception. IOG perception was initiated using split-grating stimuli constructed from luminance (L), luminancemodulated noise (LM) and contrast-modulated noise (CM). In Experiment 1, three different visibility levels were used for L and LM (or first-order) stimuli, and compared to fixed-visibility CM (or secondorder) stimuli. Eight binocularly normal participants indicated whether they perceived full horizontal or vertical gratings, superimposition, or other (piecemeal and eye-of-origin) percepts. CM stimuli rarely generated full IOG, but predominantly generated superimposition. In Experiment 2, Levelt's modified laws were tested for IOG in nine participants. Split-gratings presented to each eye contained different visibility LM gratings, or LM and CM gratings. The results for the LM-vs-LM conditions mostly followed the predictions of Levelt's modified laws, whereas the results for the LM-vs-CM conditions did not. Counterintuitively, when high-visibility LM and low-visibility CM split-gratings were used, high-visibility LM components did not predominate IOG perception. Our findings suggest that higher proportions of superimposition during CM-vs-CM viewing are due to binocular combination, rather than mutual inhibition. It implies that IOG percepts are more likely to be mediated at an earlier monocular, rather than a binocular stage. Our previously proposed conceptual framework for conventional binocular rivalry, which includes asymmetric feedback, visual saliency, or a combination of both (Skerswetat et al. Sci Rep 8:14432, 2018), might also account for IOG. We speculate that opponency neurons might mediate coherent percepts when dissimilar information separately enters the eyes. The human visual system has evolved to combine monocular inputs into a coherent, fused, binocular percept if those inputs have similar physical properties. Significant physical differences between two monocular images can lead to exclusive visibility of one eye's input for a few seconds until that eye's input is suppressed, as the formerly suppressed eye's input takes over visual awareness. This phenomenon is known as binocular rivalry 2-5. Conventional binocular rivalry (CBR) is typically generated by presenting for example, a vertical grating to one eye and a horizontal grating to the other. Perception will begin to alter between an exclusive vertical and an exclusive horizontal grating. Traditionally, CBR is known for alternation between two exclusive percepts but in transition between these exclusivity states, CBR also consists of "mixed" percepts, namely piecemeal (i.e. exclusivity in smaller local spatial zones across the visual field 6) and superimposition (i.e. percept of completely overlapping rival stimuli 7. Superimposition has been thought to be indicative of binocular fusion 7,8 .

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Lateral facilitation revealed dichoptically for luminance-modulated and contrast-modulated stimuli

Cited by 9 publications

References 56 publications

Interocular suppression patterns in binocularly abnormal observers using luminance- and contrast-modulated noise stimuli

Interocular suppression patterns in binocularly abnormal observers using luminance- and contrast-modulated noise stimuli

Grouping Effects on Foveal Spatial Interactions in Children

Contrast-modulated stimuli produce more superimposition and predominate perception when competing with comparable luminance-modulated stimuli during interocular grouping

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