It’s the Noise, Not the Motion

ABSTRACT—We tested the hypothesis that deficits on senso-ry-processing tasks frequently associated with poor reading and dyslexia are the result of impairments in ex-ternal-noise exclusion, rather than motion perception or magnocellular processing. We compared the motion-di-rection discrimination thresholds of adults and children with good or poor reading performance, using coherent-motion displays embedded in external noise. Both adults and children whowere poor readers had higher thresholds than their respective peers in the presence of high external noise, but not in the presence of low external noise or when the signal was clearly demarcated. Adults ’ performance in high external noise correlated with their general reading ability, whereas children’s performance correlated with their language and verbal abilities. The results support th