Visual Resolution and Contour Interaction*

Flom, Merton C.; Weymouth, Frank W.; Kahneman, Daniel

doi:10.1364/josa.53.001026

Cited by 442 publications

(406 citation statements)

References 12 publications

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“…Moreover, these effects are also evident in the cortical potentials (VEPs) evoked by suprathreshold vernier offsets (Steinman et al, 1985). Such interference effects are ubiquitous in spatial vision and occur for orientation discrimination (Westheimer et al, 1976), stereopsis (Butler and Westheimer, 1978), Snellen acuity (Flom et al, 1963b), as well as vernier acuity (Westheimer and Hauske, 1975 and the present study). Moreover, similar effects occur when a rectangular luminous background is added to a two dot vernier target (Williams et al, 1983;Williams and Essock, 1985).…”

Section: Discussionsupporting

confidence: 54%

“…Such interference effects are ubiquitous in spatial vision, and have been demonstrated to occur for foveal targets in tilt judgements (Westheimer et al, 1976;Andriessen and Bouma, 1976), stereopsis (Butler and Westheimer, 1978) and letter acuity (Flom et al, 1963b). Because spatial interference occurs also under dichoptic conditions (Flom et al, 1963a;Westheimer and Hauske, 1975) it has been considered to reflect a central, neural inhibitory interaction.…”

Section: Introductionmentioning

confidence: 99%

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Vernier acuity, crowding and cortical magnification

1985

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Section: Discussionsupporting

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Vernier acuity, crowding and cortical magnification

1985

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“…If these long-range connections exist in the cortical region representing the blind spot and if they are binocular in nature, then this region of striate cortex cannot be strictly monocular as is currently believed. The goal of the present study is to test psychophysically whether binocular interactions exist in the region of the cortex that corresponds to the blind spot in humans by measuring dichoptic contour interaction using stimuli that would be expected to stimulate this "monocular" cortical region, Visual perfo~ance is degraded when additional contours are placed in the neighborhood of the stimulus used to measure ~rfo~ance, This degradation of performance in the presence of flanking contours is termed contour interaction (Flom, Weymouth & Kahneman, 1963;Bouma, 1970). Contour interaction extends radially from the test stimulus as far as half the eccentricity of the test stimulus (Bouma, 1970;Andriessen & Bouma, 1976;Toet & Levi, 1992).…”

Section: Blind Spot Contour Interaction Long-range Horizontal Connectmentioning

confidence: 99%

Long-range dichoptic interactions in the human visual cortex in the region corresponding to the blind spot

Tripathy

Levi

1994

Vision Research

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Tbe region of tbe visual field of one eye tbat corresponds to tbe blind spot of the coutraIatera1 eye is beiieved to be monocular. We measured dicboptic coatour interaction in this region of tbe visual field in bumans by having observers report tbe orientation of a test letter "T" presenH to tbis region, in the presence of thud&g T's presented around tbe blind spot of the fellow eye. A large drop in performance was seen because of tbe Bauks, showing clearly tbe existence of dicboptic contour interaction in this 'cmonocular" region of tbe visual field. Tbis suggests that the cortical representatioa of the region of tbe visual field tbat corresponds to the -t&ate& eye's blind spot is sot strictly monocular. Tbe absence of direct retinal aiferents from oue eye to tbis region of cortex swggests tbe involvement of horizontal cortical connectious in tbe contour interaction phenomenon. Our estimates of the extent of contour interaction in mm of striate cortex are comparable to the reported lengths of the long-range horizontal connections in tbe striate cortex of monkeys. Our results are consistent with the proposition that long-range horizontal conuections of the striate cortex may mediate the eontour interaction p~~rnenon.

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“…1 The crowding phenomenon occurs when an optotype presented in isolation is more easily identified than one presented in a horizontal row of the same sized optotypes. Various theories have been put forward for the crowding phenomenon, for example, that it is the result of contour interaction whereby additional stimulation from adjacent optotypes causes confusion, [5][6][7][8] or that a reduction of lateral retinal inhibition may be a causal factor. 9 Hess et al 10 reported that the phenomenon was linked to the physical characteristics of the stimulus more than the inhibitory interaction.…”

Section: Introductionmentioning

confidence: 99%

The logMAR Kay picture test and the logMAR acuity test: a comparative study

Elliott

Firth

2007

Eye

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Purpose To compare the level of visual acuity with crowded and uncrowded versions of the logMAR acuity test and the Kay picture test in amblyopia. Methods A prospective study was carried out on 51 participants with amblyopia (strabismic n ¼ 17; anisometropic n ¼ 10; combined n ¼ 24), mean age 10 years 8 months. The amblyopia was defined as severe/moderate (o0.250 logMAR), n ¼ 41 or mild (X0.250 logMAR), n ¼ 10. Visual acuity was assessed uniocularly using the crowded and uncrowded logMAR acuity tests and the logMAR crowded and uncrowded Kay picture tests in random orders. Results The mean visual acuity outcome using the logMAR crowded Kay picture test (0.34370.150) was comparable (P ¼ 0.084) with the mean outcome using the crowded logMAR acuity test (0.40270.188). However, the mean acuity difference between these two tests in the subgroup with severe/moderate amblyopia (0.07470.036) was statistically significant (P ¼ 0.0382). The uncrowded logMAR acuity test significantly overestimated visual acuity when compared with the logMAR crowded Kay picture test (Po0.005) by a mean of 0.08870.008. ConclusionThe logMAR crowded Kay picture test is a useful tool in clinical practice. The test design takes the crowding phenomenon into account. It provides visual acuity measures more comparable with the gold standard crowded logMAR acuity test than the uncrowded logMAR acuity test. However, the outcomes in poorer acuities should still be viewed with caution.

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Visual Resolution and Contour Interaction*

Cited by 442 publications

References 12 publications

Vernier acuity, crowding and cortical magnification

Vernier acuity, crowding and cortical magnification

Long-range dichoptic interactions in the human visual cortex in the region corresponding to the blind spot

The logMAR Kay picture test and the logMAR acuity test: a comparative study

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