Dyslexia as a limitation in the ability to process information

In an earlier paper (Miles and Wheeler 1975) it was reported that dyslexic subjects, aged over 13, were less able than suitably matched non-dyslexic subjects to respond correctly to arrays of tachistoscopically presented digits. A further experiment is now reported involving a younger age-group: 15 dyslexic subjects, average age twelve and one-half, were matched for spelling age with 15 non-dyslexic subjects, average age eight and one-half; and since the dyslexic subjects were appreciably less successful it is argued that “maturational lag” does not, on its own, fully account for the difference in performance between the two groups. A similar procedure was repeated with 41 dyslexic and 41 non-dyslexic subjects, all aged between 10.4 and 14.4, both with and without the introduction of a visual masking stimulus immediately after the test stimulus. Twenty undergraduate “fast-readers,” 20 undergraduate “slow-readers,” and four undergraduate dyslexic subjects were also compared both on their responses to tachistoscopically presented digits and on their performance in a visual search task. The results, taken in conjunction, suggest that dyslexia can be regarded as some kind of limitation in the ability to process information, perhaps affecting in particular the “visual code store” postulated by Posner et al. (1969). This paper was prepared for deliveryin absentia at the 27th Annual Conference of The Orton Society, in New York City, November 1976.