COHERENT MOTION DETECTION AND LETTER POSITION ENCODING

We identified 24 'good' and 24 'poor' coherent motion detectors from a n unselected sample of young adults. The two groups were matched for r eading ability, age and IQ. All subjects carried out two tasks in whic h optimal performance depended on accurate letter position encoding: a lexical decision task and a primed reaction time task. We found that accurate letter position encoding was predicted by performance in the motion detection task. Since coherent motion detection depends on inpu t from the magnocellular pathway, these findings suggest that informat ion carried by the magnocellular system may be required for encoding l etter position. Furthermore, these results may have implications for r eading disability which is said to be associated with magnocellular dy sfunction. (C) 1998 Elsevier Science Ltd. All rights reserved.