Charlotte C. Mitchum

Empirically derived probabilities for grapheme-to-phoneme correspondences in english

Prior probabilities of graphemes and conditional probabilities for their pronunciation as specific phonemes are given based on a corpus of 17,310 English words. Phonemes are as given in recent editions ofWebster’s New Collegiate Dictionary, with minor revisions; graphemes are defined as letters or letter clusters corresponding to single phonemes. Grapheme-phoneme probabilities were derived from a revised table of frequency of occurrence of phoneme-to-grapheme correspondences generated in a study of spelling regularities (P. R. Hanna, J. S. Hanna, Hodges, & Rudorf, 1966). This quantitative descriptive information provides an index of the strength of particular grapheme-phoneme associations in English. Suggestions are made for the utilization of these probabilities as estimates of spelling/sound predictability in reading research.

Grammatical class and imageability in aphasic word production: their effects are independent

Abstract This paper addresses the recent claim that grammatical class differences found among aphasic patients may reflect semantic factors such as ease of imageability rather than lexical/syntactic class. Nouns and verbs equated for rated imageability, frequency and length were elicited as completions for spoken sentences. Five aphasic patients with significantly better production of nouns than verbs in picture naming continued to show a significant grammatical class effect in the completion task. Two patients with significant imageability effects in oral reading continued to show imageability effects in sentence completion, but only one of these patients showed any difficulty producing verbs. Inspection of the individual patient data indicated that either grammatical class, or imageability, or both variables may affect patient performance, but that their effects are independent of one another.

Diagnosis and treatment of the non-lexical route in acquired dyslexia: an illustration of the cognitive neuropsychological approach

Abstract This paper illustrates a recent approach to diagnosis and treatment of cognitive deficits secondary to focal brain damage. An information processing model of the normal system is used as a basis for the diagnosis of the functional cognitive impairment(s) that result in a patients symptoms. An intervention program is then designed to address these functional deficits. The case illustrated here demonstrated almost total inability to “sound out” printed words, a symptom that was linked to impairments to two separable components of the model of normal reading. Several intervention techniques were developed that resulted in improvement in the two impaired components, but these improvements brought about little change in functional reading ability. The patients response to treatment suggested the involvement of a third deficit, and necessitated a modification of the original model of reading. Results are discussed with an emphasis on the interpretation of specific processing changes that can be brought about through carefully targeted intervention. One primary contribution of the approach is argued to be the formulation of diagnostic tests, focused on specific components, that predict the likelihood that a patient will respond to a particular intervention.

Assessing the Elements Contributing to a "Mapping" Deficit: A Targeted Treatment Study

Aphasic patients with excellent comprehension of word meanings frequently fail to understand simple declarative sentences in which either of two nouns could reasonably serve as agent of a transitive action. This study employed targeted treatment of this comprehension problem in a chronic aphasic patient (E.A.) in an attempt to isolate the source or sources of his comprehension failure. Treatment exercises that relied on error feedback in sentence-picture matching or verification initially were not effective. Comprehension of active and passive sentences improved only after both structures were explicitly compared and linked to a picture. Subsequently E.A. maintained consistently accurate interpretation of both sentence types in the treatment exercises as long as the full sentence was available to him. E.A. learned to assign thematic roles using a limited set of cues in the surface structure. Although improvement was reported in untreated sentences, the degree of generalization and the level of performance differed across tasks and appeared to be attributable to cognitive impairments that were not addressed by the treatment. Results are interpreted as evidence suggesting that multiple impairments contribute to failure of sentence comprehension tasks.

Model-guided treatment to improve written sentence production: A case study

Abstract Impaired production of both spoken and written sentences was studied in a case of chronic aphasia. Assessment of the production impairment, guided by reference to a model of the processes normally involved in the production of spoken sentences, revealed two specific points of disturbance: (1) poor retrieval of lexical main verbs and (2) poor production of the morphological elements linked to verbs. Two interventions were targeted at the early stages of sentence construction and limited to practice in the written modality. Generalization of treatment-induced processing changes in spoken sentence production is discussed in support of the hypothesis that the intervention tasks isolated pre-phonetic and pre-articulatory aspects of sentence production. Expansion of the model of normal, spoken sentence production is proposed in order to accommodate details regarding the nature of processing requirements in written sentence production.

The Cognitive neuropsychological approach to treatment of language disorders

(1995). The Cognitive neuropsychological approach to treatment of language disorders. Neuropsychological Rehabilitation: Vol. 5, No. 1-2, pp. 1-16.

Cognitive treatments of sentence processing disorders: What have we learned?

Several cognitive neuropsychological studies describing treatments of sentence processing disorders have been reported in recent years. We review the outcome of 10 studies that describe treatment outcomes for 17 aphasic patients. Although the studies used different approaches to intervention, they shared the goal of improving reversible sentence comprehension, and they targeted a hypothesised deficit of “thematic mapping”. Several trends in treatment outcomes were observed. In most cases, there was strong evidence that the treatments induced a change in the pattern of sentence processing. Moreover, the outcomes indicated that impaired reversible sentence comprehension can arise from a range of impairments, only some of which directly implicate structural and/or lexical deficits assumed to be the source of poor thematic mapping abilities. Patterns of post-therapy generalisation within and across processing modalities appeared to be related, among other things, to the therapy approach and to the selection of treatment materials. These findings are discussed with regard to the theoretical implications of sentence processing treatment data.

Production of nouns and verbs in aphasia: Effects of elicitation context

This study investigated the ability of 10 aphasic speakers and 9 normal controls to produce unambiguous, frequency-matched nouns and verbs in four elicitation conditions. Two auditory conditions included naming to definition and sentence completion; two picture conditions preceded the presentation of the picture with an auditory cue consisting of a question (what is the action shown here?) or a sentence completion (this is a picture of the action to...). Patients were grouped in terms of whether they demonstrated only word retrieval problems (anomia), or also showed difficulty with sentence comprehension and production. Contrary to expectations, there were no reliable effects of elicitation condition on performance. Although both groups of aphasic speakers found verbs more difficult than nouns to retrieve across conditions, the sentence production-impaired group showed a more severe impairment of verb production that was reliable for individual subjects. Results reinforce the importance of grammatical class as a factor in the word retrieval impairments found in aphasia.

Comprehension of reversible sentences in aphasia: the effects of verb meaning

Abstract Comprehension of semantically reversible active and passive voice sentences was tested in a timed sentence/picture verification task. Three sets of six verbs were identified that incorporated different features of meaning relevant to the assignment of nouns to the thematic role of agent. Normal control subjects showed an effect of verb set on their response times, with significant effects between sets in the predicted direction. A group of aphasic patients without sentence comprehension disorder also showed a significant effect of verb set despite long and variable response times. A group of patients with reversible comprehension disorder in screening tasks showed weaker effects, primarily because of the use of consistent response biases that ignored the sentence verb. An experimental treatment of active/passive comprehension was conducted with two of these latter patients; one patient reached ceiling in post-testing, and the other showed significant improvement but demonstrated residual comprehension problems that indicated differences across verb sets. Results support the critical importance of verb meaning to normal and aphasic sentence comprehension.

Traditional and contemporary views of aphasia: implications for clinical management

The following is an attempt to consider how various ways of thinking about the aphasic condition influence how the problem is approached for rehabilitation. The fundamental theory of three popular, traditional approaches to assessment of aphasia are considered with particular regard to their consequential influence upon clinical management. The possibilities and limitations of clinical integration of the relatively new approach of cognitive neuropsychology are discussed.