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Graphemic discrimination by educable mentally retarded and slow learners Bain, David Alexander

Abstract

The visual discrimination of rotations and reversals of single letters within five letter nonsense words was studied in a five-to-one match-to-sample format. The subjects were educable mentally retarded and slow learners, chronological age 8-16 years and mental age 5-12 years. Rotation and reversal reading errors were reclassified as disorientation and resequencing errors. Significant differences were found between the following subcategories of letter disorientation errors. Horizontal disorientations were more frequent than vertical and rotational errors. Disorientation errors were most frequent in the initial and final portions of words. Ten of the eighteen possible letter disorientations, e.g. "d-b" and "q-b" occurred at different rates. Most of the reciprocal letter errors such as the disorientation from "d to b" or from "b back to d" occurred at different rates from one another. An empirical basis for making typographic changes to the letters b, d, p, and q to reduce the frequency of disorientation errors was established through an extensive review of the literature. Reviews were made of the literature describing the etiology of disorientation and resequencing errors and the characteristics of typography influencing visibility and legibility. Also, the research on geometric and graphemic form perception was reviewed to establish how children perceive orienta-tional and sequential changes of visual stimuli. Before testing the effectiveness of the typographic changes, positive reinforcement was used to increase the subjects' level of performance to approximate their current level of performance capability. An effective treatment was expected to increase the subjects' reinforced level of performance, that is, to teach new skills and to increase their level of capability. Under these conditions the typographic modifications failed to significantly decrease the frequency of disorientation errors. A review was also made of the relationship between reading errors and opthalmological factors. Performance on the Keystone Tele-binocular Visual Survey (1961) was not predictive of disorientation errors.

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