Letter Confusability Research Articles

ON THE ORIGIN OF VISUAL DYSLEXIA

Analysis of the binocular co-ordination errors of a young dyslexic reveals a simple optical explantation for one of two types of letter confusion found in dyslexia. Although binocular control was grossly abnormal in reading, no ocular defect could be found in standard ophthalmic and orthoptic tests. Re-examination of the same patient six years later, again showed no ocular defect on normal testing but binocular movements in reading, while still abnormal, showed no trace of the striking original defect. This complete masking of the original condition with time must severely restrict the value of mass surveys of established dyslexics.

An Analysis of Letter Reversals in Children and a Model for an Approach to Remediation

This article proposes an explanatory model of letter reversals and confusions in the early grades. It examines the relationship between such reversals and certain cybernetic and mathematical theories about the perception of shapes. Using the model proposed, it suggests certain instructional strategies and remedial techniques for dealing with letter reversals and confizsions.

Misspelling analysis in dyslexia: Observation of developmental strategy shifts

Poor spelling is an inevitable concomitant of dyslexia (Critchley 1975; Naidoo 1972; Rutter 1978). Poor spelling is difficult to remediate even in those dyslexic persons who are able to profit from intensive instruction in reading. However, in spite of the common observation that low spelling achievement is a hallmark of dyslexia, the phenomenon has been studied little, and our knowledge of both the disability and how to remediate it remains extremely limited. Although there is little well designed spelling research in the literature, it has been commonplace for clinicians and educators to characterize dyslexia by reference to aspects of spelling performance. Not only is poor spelling achievement cited, but a higher frequency of several types of spelling errors are attributed to the dyslexic population. Those most often described are: (a) letter order reversals or confusions (Boder 1973; Critchley 1975; Johnson and Myklebust 1967; Orton 1937); (b) "bizarre" misspellings resulting from poor audiophonic analysis of words and poor ability to learn and apply phonic correspondences (Boder 1973; Ingram, Mason, and Blackburn 1970; Nelson and Warrington 1974; Sweeney and Rourke 1978); and (c) failure to remember sight words in reading and spelling because of poor visual memory for language (Boder 1973; Ingram et. al. 1970; Johnson and Myklebust 1967). While letter order errors have generally not been associated with a specific subgroup of dyslexies, both the audiophonic difficulties and the verbo-visual memory difficulties have been attributed to specific subgroups of dyslexies defined on the basis of their reading and spelling patterns (Boder 1973; Camp and Dolcourt 1977; Ingram et. al. 1970). Evidence based on neuropsycholog ical assessment in favor of these subgroup classifications has come from the work of Denckla (1978) and Mattis, French, and Rapin (1975).

The Effect of Food and Water Deprivation and Satiation on Recognition

Food and water deprived and satiated subjects, as well as control subjects, were shown words presented tachistoscopically for .01 sec until word recognition. Five food-relevant, five water-relevant, and five neutral (animal) words of high string frequency were matched for letter confusability and letter predictability. Analyses of the data, in terms of number of presentations until recognition as well as number of words recognized at selected presentations, revealed that the amount but not the type of deprivation significantly altered word recognition. Moreover, the effect of motivation was significant already on the first slide presentation, while the effects of word characteristics (word category and generated value) occurred only after a number of presentations.

An analysis of tactile letter confusions

A confusion matrix of the whole block capital letters of the alphabet was obtained so as to examine the nature of tactile letter recognition, using a 17 by 17 matrix of tactile stimulators placed against blind subjects’ backs. A hierarchical cluster analysis and a nonmetric multidimensional scaling technique were applied to the matrix. The results of the two analyses were consistent with each other and indicated that at least three independent basic letter features—enclosing shapes, vertical parallel lines, andangle of lines—play important parts in tactile letter recognition. Most confusion may be attributable to displacement of the apparent loci, omission or fusion of loci of stimulation, and failure to detect gaps in the tactile letters.

An operations research approach to the modeling and analysis of different feature sets proposed for human perception of capital letters

A Markov chain feature transition model of capital letter recognition is presented for synthesizing the empirically derived 26 × 26 capital letter confusion matrices. The transition probabilities associated with the features in the model are used as solution vector in an optimization problem, the objective being to minimize the sum of per cell squared differences between the empirical confusion matrix and the synthesized matrix. Three proposed feature sets are used on conjunction with the model to synthesize three empirical confusion matrices. Variants of the model are considered and results are tabulated and analyzed.

I.t.a. revisited

i.t.a. revisited

TRAINING LETTER DISCRIMINATION IN FOUR‐YEAR‐OLD CHILDREN1

Four-year-old children were tested on letter discrimination. Subjects in two experimental groups went through an experimental training program on a match-to-sample apparatus. Subjects in the experimental-critical group were given reinforcers for responding to features of the stimuli thought critical for discriminating letters while subjects in the experimental-noncritical group were given reinforcers for responding to non-critical features. Subjects went through the training program daily until they reached criterion; then they were posttested on letters. Subjects in a control group received no training but were posttested. Subjects in all groups made fewer errors on the posttest. Subjects in the experimental-critical group made significantly fewer posttest errors than subjects in the experimental-noncritical group, lending support to the hypothesis that reinforcement of discriminative responding to critical features of letter-like stimuli results in greater improvement in letter discrimination than reinforcement of discriminative responding to noncritical features of stimuli. Analysis of confusion matrices provided tentative indications of the nature of letter confusions in 4-yr-old children.

Frustration and reading problems

The presence of frustration-produced anxiety in varying degrees as a concomitant effect of reading disability has been amply documented. Bryant (1962) has noted anxiety as one of the underlying causes of the "almost universal" presence of emotional difficulties in reading disorders. Anxiety manifests itself in myriad ways, some subtle (as in the child who develops avoidance behaviors, or persists in letter and word confusions and reversals), and some more obvious (as in children who have temper tantrums, become overtly aggressive, or soil themselves during reading instruc tion). And yet in the face of this general agreement there have been few attempts to relate the two, frustration and reading problems, in any but an indirect, contributory manner. Hilgard's (1967, p. 514) statement is typical of the prevailing view, "The persistence of difficulties in arithmetic, reading, and spelling among bright children (and some adults) may be explained in part as a consequence of errors similarly stereotyped by early frustration." It has become apparent to me that it is possible, perhaps even probable, that the relationship between frustration and reading problems is less indirect than it has been perceived to be. The discussion which follows will indicate the marked similarity in behaviors between animal and human subjects who have been frustrated, and children and adults who have been labeled as cases of reading disability. Observation of these similarities indicates the possibility of a more direct link between the two and may serve to explain why therapy, as Eisenberg (1962, p. 6) has noted, "is most often a painfully slow process with small gains despite large efforts, and at times there is unfortunately no visible gain at all." It is hoped that further investigations will be encouraged by demonstra tion of the striking likenesses in behaviors manifested by both animals and humans placed in persistent, no-escape, frustration situations, and in children with apparently intractable reading problems, who may well view continuing but unsuccessful efforts at instruction as persistent, no-escape frustration situa tions.

Congruency factors related to visual confusion of English letters.

An index was developed to determine the congruency of letter pairs in the lower-case English alphabet in Century Schoolbook print. The index was based on the ratio of common area to independent area. The congruency matrix of the 325 letter pairs was factor analyzed. Five factors indicated major letter groups and illustrated critical features for discrimination within letter groups.