Attention, dyslexia, and the line-motion illusion.

Dyslexic readers have been found to have a reduced line-motion illusion. This has been interpreted as evidence for an attention deficit of magnocellular origin. We show that this interpretation has severe problems: 1) to link reduced line-motion illusion to attention overlooks other factors, 2) to link the line-motion illusion specifically to the magnocellular system is problematic because the illusion can be obtained with isoluminant stimuli, 3) reduced illusory motion in dyslexic individuals may reflect sensory deficits, and 4) to link dyslexia specifically to the magnocellular system is in general problematic.