Recent findings indicate that motion processing is impaired in a large proportion of poor readers.
These results have been interpreted as reflecting a magnocellular deficit in dyslexia. The minimal interval required to detect direction of apparent motion of a single dot moving horizontally between the right and left visual fields was significantly longer in dyslexics. In a coherent-motion task, a significant group difference was found when the adaptive variable was presentation time, but not when the adaptive variable was coherence. Motion detection measures were only moderately correlated with one another and with reading, and only marginally correlated with contrast sensitivity in the range governed by the magnocellular system. We conclude that associating difficulties in motion detection, contrast detection, and reading with a single magnocellular deficit is questionable.