Visual Learning and the Brain: Implications for Dyslexia

Matthew H. Schneps, L. Todd Rose, and Kurt W. Fischer

(2007: in press) Journal of Mind, Brain, and Education (Vol 1, No. 3).

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 tradeoff between abilities for sequential search versus contemporaneous comparisons. The parameter of PCR (periphery-to-center ratio) 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.

Magnocellular Deficit in Dyslexia: a Gradient?

Matthew H. Schneps, L. Todd Rose, and Kurt W. Fischer

(2007: in review) Journal of Mind, Brain, and Education

ABSTRACT Dyslexia has been associated with deficits for visuospatial tasks such as visual search, attributed to abnormalities in the magnocellular pathways. But, people with dyslexia are seen to outperform readers for tasks involving visual anomaly detection (von Karolyi, Winner et al. 2003) and spatial learning (Howard, Howard et al. 2006), tasks that benefit from advantages for peripheral processing. Peripheral advantages in dyslexia have been reported (e.g. Facoetti, et al., 2000), and the speed of this peripheral processing suggests it is unlikely that deficits in attention can account for these effects. Building on a mechanism proposed to explain fast peripheral processing in those unimpaired (Carrasco, McElree et al. 2003), we suggest that the "magnocellular deficit" in dyslexia is better characterized as a gradient in the distribution of magnocellular neurons that tends to concentrate these cells in the retinotopic periphery of V1 at the expense of the center, perhaps due to an error in neural migration.

Presentations

Science and Learning Disabilities: Putting Theory into Practice

Matthew H. Schneps, L. Todd Rose

Council of Chief State School Officers SCASS Meeting, October 11, 2007, Washington, DC

Presentation PowerPoint (includes navigation buttons)

Dyslexia and Astronomy

Matthew H. Schneps, L. J. Greenhill, L. T. Rose

American Astronomical Society 211th Meeting Austin, TX, 7-11 January, 2008

Abstract

Asynchrony Detection of Visual and Auditory Speech by Adolescents With Autism

Ruth B Grossman, Matthew H Schneps, and Helen Tager-Flusberg

Autism Consortitum - 2nd Scientific Retreat (2007)

Abstract

Press Releases

Learning Disabilities Are Sometimes Advantageous

New theory suggests that disabilities such as dyslexia may bring advantages for some forms of learning

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