Age at Onset of Blindness in Visual Imagery Development

Abstract

Eleven college students who were born blind, 16 blinded at approximately 15 years of age (range 6 to 30 years), and 16 with normal vision were asked to visualize the letters of the uppercase, typeset, English alphabet. If the shape of a letter had one or more curves, like B, subjects were to classify it as curved. If the shape of the letter had no curves, like A, they were to classify it as straight. Letters were presented one at a time in random order. Reaction time and errors were recorded. Controlling for knowledge of the alphabet, the early blind took longer and made more errors than did the late blind and sighted, who did not differ from each other. The results suggest that age of onset of blindness influences the development of visual imagery.