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Optom Vis Sci. 2007 Mar;84(3):229-36.

L/M speed-matching ratio predicts reading in children.

Author information

  • 1Department of Psychology, Claremont McKenna College, Claremont, California 91711, USA. chris.chase@claremontmckenna.edu

Abstract

PURPOSE:

Many behavioral studies have found impaired perception of dynamic visual stimuli in dyslexia and several neuroimaging studies have found reduced activation of the human motion area MT+ in dyslexia. These results are often interpreted as a magnocellular (MC) deficit in dyslexia. It has also been claimed that colored filters can help dyslexics to read. One defining feature of the MC-pathway is a greater weight for L-cone input than M-cone input, and at most very weak S-cone input. We measured the subjective speed matches between L-, M-, and S-cone isolating stimuli in good and poor readers.

METHODS:

Subjects performed a speed-matching task with drifting cone-isolating stimuli to find the point of subjective equality between two drifting patterns. Such a task is known to activate cortical area MT+, presumably via the MC-pathway.

RESULTS:

L- to M-cone speed-match ratios were negatively correlated with single-word (r=-0.46) and irregular-word reading (r=-0.56) but not with non-word reading.

CONCLUSIONS:

Results suggest that relative L-cone sensitivity within the MC-pathway may limit orthographic reading performance.

[PubMed - indexed for MEDLINE]
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