TASK-DETERMINED STRATEGIES OF VISUAL PROCESS

Lateral masking in the peripheral field of vision obscures letter reco gnition and is not accounted for by diminished acuity. In measuring la teral masking between letters in the peripheral visual field we accide ntally discovered that ordinary readers and severe dyslexics differ ma rkedly in tachistoscopic letter recognition tasks. Tests were devised to measure the differences accurately. Ordinary readers recognize lett ers best in and near the center of gaze. Recognition falls off rapidly with angular distance in the peripheral field. Severe dyslexics recog nize letters farther in the periphery in the direction of reading (Eng lish-natives to the right, Hebrew-natives to the left). They have mark ed lateral masking in and near the center of the field when letters ar e presented in aggregates. With dyslexia as an example, we proposed th at the distribution of lateral masking is a task-dependent strategy in visual perception. To test this notion we designed an active practise regimen for 4 severe adult dyslexics, who within a few months improve d sharply in reading. At the same time their test results changed to t hose of ordinary readers. We conclude that there are switchable task-d etermined pre-cognitive strategies of vision that can be learned and t hat the distribution of lateral masking may be part of what is learned .