Task-determined strategies of visual process

Geiger, Gad; Lettvin, Jerome Y.; Zegarra‐Moran, Olga

doi:10.1016/0926-6410(92)90004-b

Cited by 41 publications

(46 citation statements)

References 16 publications

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“…According to Facoetti et al (2006), these results indicate that dyslexic children are characterized by significant distractibility by stimuli appearing in the right visual field and a kind of left mini-neglect. Right visual field distractibility has also been found in dyslexic English-speaking adults (Geiger, Lettvin, & Zegarra-Moran, 1992). Based on these results and our own in 6-year-old children, we hypothesize that dyslexic subjects may have difficulties acquiring the efficient attentional processes involved in reading, specifically the dominant orientation of selective attention toward the beginning of a letter string, which requires inhibiting the biased distribution of modulatory attention toward the right visual field.…”

Section: Discussionmentioning

confidence: 90%

Attentional Processing of Letter Strings by Children

Leclercq¹,

Siéroff

2014

Child Neuropsychology

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Reading a letter string requires attentional orienting toward the beginning of the string (left-dominant orientation), followed by orienting along the string. These attentional-orienting processes differ according to the lexicality of the letter string: Sequential processes apply when reading nonwords or pseudowords, while words can be processed more globally. The aim of this study was to evaluate the development of these attentional processes involved in reading. We conducted two experiments in 6- (first grade), 7- (second grade), and 9-year-old (fourth grade) children, using a procedure that required the detection of a letter (Experiment 1) or a nonletter (Experiment 2) target in a string of five characters. The target character could occur in the second (left) or fourth (right) position in the string. Results showed an advantage for left nonletter targets as early as age 6 and of left letter targets as early as age 7. In 6-year-olds, only good readers detected a left letter target faster than a right letter target; others detected a right letter target faster. Thus, dominant orienting toward the beginning of the letter string is not fully developed in children before the second year of reading. A possibility is that beginning readers have difficulties inhibiting an attention-orienting bias toward the right visual field in linguistic tasks. The results also showed that the lexicality effect on these attentional processes develops gradually until the fourth year of reading. We believe that the procedure used in this study will be very valuable for evaluating attentional difficulties during reading acquisition.

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Section: Discussionmentioning

confidence: 90%

Attentional Processing of Letter Strings by Children

Leclercq¹,

Siéroff

2014

Child Neuropsychology

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“…Evidence that some individuals with dyslexia exhibit a visual bias toward the periphery first came to light in studies measuring letter identification in the peripheral field (Geiger & Lettvin, 1987; Geiger, Lettvin, & Zegarra‐Moran, 1992). In these studies, researchers used a mechanical shutter (tachistoscope) to briefly flash (for ∼10–25 ms) pairs of letters simultaneously in the center and in the periphery, observing accuracy of response as a function of eccentricity for the outermost letter.…”

Section: Dyslexia: a High‐pcr Group?mentioning

confidence: 82%

Visual Learning and the Brain: Implications for Dyslexia

Schneps

Rose

Fischer³

2007

Mind Brain and Education

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ABSTRACT— The central and peripheral visual fields are structurally segregated in the brain and are differentiated by their anatomical and functional characteristics. While the central field appears well suited for tasks such as visual search, the periphery is optimized for rapid processing over broad regions. People vary in their abilities to make use of information in the center versus the periphery, and we propose that this bias leads to a trade‐off between abilities for sequential search versus contemporaneous comparisons. The parameter of periphery‐to‐center ratio (PCR) describes the degree of peripheral bias, which evidence suggests is high in many people with dyslexia. That is, many dyslexics favor the peripheral visual field over the center, which results in not only search deficits but also (more surprisingly) talents for visual comparison. The PCR framework offers a coherent explanation for these seemingly contradictory observations of both deficit and talent in visual processing. The framework has potential implications for instructional support in visually intensive domains such as science and mathematics.

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“…We envision that the model could be used to optimize fonts, letter spacings, or line spacings for robustness to crowding effects, potentially improving reading performance. There is also some evidence linking dyslexia to crowding with larger-than-normal critical spacing 18,41,42 , and the model might serve as a useful tool for investigating this hypothesis. Additional examples are provided in Figure 7b–c, which show how camouflaged objects, which are already difficult to recognize foveally, blend into the background when viewed peripherally.…”

Section: Discussionmentioning

confidence: 99%

Metamers of the ventral stream

2011

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The human capacity to recognize complex visual patterns emerges in a sequence of brain areas known as the ventral stream, beginning with primary visual cortex (V1). We develop a population model for mid-ventral processing, in which non-linear combinations of V1 responses are averaged within receptive fields that grow with eccentricity. To test the model, we generate novel forms of visual metamers — stimuli that differ physically, but look the same. We develop a behavioral protocol that uses metameric stimuli to estimate the receptive field sizes in which the model features are represented. Because receptive field sizes change along the ventral stream, the behavioral results can identify the visual area corresponding to the representation. Measurements in human observers implicate V2, providing a new functional account of this area. The model explains deficits of peripheral vision known as “crowding”, and provides a quantitative framework for assessing the capabilities of everyday vision.

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Task-determined strategies of visual process

Cited by 41 publications

References 16 publications

Attentional Processing of Letter Strings by Children

Attentional Processing of Letter Strings by Children

Visual Learning and the Brain: Implications for Dyslexia

Metamers of the ventral stream

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