Complex graphemes as functional spelling units: evidence from acquired dysgraphia.

The visual word recognition literature suggests that complex graphemes (or digraphs) such as CK function as units. This proposal has also been put forward in recent spelling models (Houghton and Zorzi, 2003) and the study we report on here provides initial empirical support for the claim. We performed detailed analyses of the spelling performance of two brain-damaged individuals with graphemic buffer deficits. Results revealed that (a) FM and BWN made fewer errors on consonant digraphs (e.g., CK) than on matched controls clusters (e.g., CR) and (b) BWN produced more transposition errors on vowel digraphs than on control clusters. These result support the view that digraphs are represented as units in which the relative order of constituent letters is encoded.

Syntactic mediation is not obligatory during lexical access: evidence from a single-case study of Welsh Aphasia.

Current models of word production assume the existence of functionally distinct lexical-syntactic and word-form representations. However, there are competing hypotheses about whether prior access to syntactic properties of words is obligatory during lexical retrieval. In this paper we report preliminary evidence from the single case study of a Welsh-speaking patient with a lexical access deficit. We examined the patient's ability to access word forms and to retrieve information about the grammatical gender of Welsh nouns. The data show no correlation between the retrieval of word-form and grammatical gender information. This pattern of performance is inconsistent with hypotheses postulating obligatory syntactic mediation in lexical production.

Superior written over spoken picture naming in a case of frontotemporal dementia.

Two main hypotheses have been proposed regarding the role of phonology in written word production. According to the phonological mediation hypothesis, the retrieval of the lexical phonological representation of a word is an obligatory prerequisite to the retrieval of its spelling. Therefore, deficits to the phonological lexicon should affect both spoken and written picture naming. In contrast, the orthographic autonomy hypothesis posits that the lexical orthographic representations of words can be accessed without any necessary phonological mediation. In support of this view, cases of preserved written naming despite impaired lexical phonology have been reported following brain damage. In this report, we replicate this basic pattern of performance in case YP, a 60-year-old woman with a pattern of frontotemporal dementia. As her disease progressed, YP's ability to write down the names of pictures remained very good despite a severe decline in oral naming. Further testing indicated that this deficit was not primarily due to an articulatory or post-lexical phonological deficit. YP's case provides strong additional support for the orthographic autonomy hypothesis. The significance of this case with respect to the characterization of dementia syndromes is discussed.

[Acquired dyslexias and dysgraphias under the prism of cognitive neuropsychology: a model for the Spanish language]. / Las dislexias y disgrafías adquiridas bajo el prisma de la neuropsicología cognitiva: un modelo para la lengua castellana.

The present paper discusses the different clinical manifestations of acquired disorders of reading and writing from a neurocognitive viewpoint. Based on a specific functional architecture of reading and writing--a cognitive model; presented as well--the different syndromes of acquired dyslexias and dysgraphias, that have been described in the specialized literature during the last 25 years, will be reviewed. The different pathologies are distributed along three different functional axes: a plurimodal component, including the semantic system, for the description of peripheric disorders of reading and writing; a lexical block which is justified by the findings in patients with surface dyslexia/dysgraphia; and a third, sublexical component, in order to illustrate the different functional impairments in phonological dyslexia/dysgraphia. Following the description of syndromes due to selective "functional lesions", we discuss deep dyslexia/dysgraphia, a syndrome due to multiple functional lesions. All of the syndromes will be justified and discussed with respect to the different components of the functional architecture presented and are based on cases of the literature and personal observations. Concluding remarks will evaluate the new insights gained by the presented functional arquitecture in relation to other cognitive models for the analysis of reading aloud and writing to dictation of single words.

Las dislexias y disgrafías adquiridas bajo el prisma de la neuropsicología cognitiva: un modelo para la lengua castellana / Dyslexias and dysgraphies acquired under the prism of cognitive neuropsychology: a model for the Castillian language

En este artículo, siguiendo el enfoque nacido con las ciencias cognitivas, se discuten las distintas patologías dentro del campo de las dislexias y las disgrafías adquiridas. Basado en un modelo cognitivo, una arquitectura funcional -presentada también-, se abarcan los distintos síndromes que se han descrito en la literatura especializada durante los últimos 25 años. Las distintas patologías se presentan en tres bloques cognitivos: un bloque plurimodal para los trastornos periféricos (dentro del cual también se consideran las alteraciones semánticas); un bloque léxico, cuya funcionalidad es evidente a partir de la dislexia/disgrafía de superficie, y un bloque subléxico que sirve para detallar los trastornos subyacentes a la dislexia/disgrafía fonológica. Una vez descritos los problemas concretos, debidos a lesiones funcionales selectivas, se discuten los trastornos múltiples, la dislexia/disgrafía profunda. En todos los casos, se justifican plenamente muchos de los componentes del modelo basándose en casos reales. Finalmente, como conclusiones, se evalúan las aportaciones novedosas de esta arquitectura funcional en relación con otros modelos cognitivos para el análisis de la lectura en voz alta y la escritura al dictado de palabras aisladas. (AU)

Educational level and the word frequency effect: a lexical decision investigation.

It is known that speed and accuracy in recognizing words are constrained by the frequency of occurrence of these words ("frequency effect"). This study examines the relationship between educational level and the word frequency effect. We postulated that individual exposure to words that are rated lower in frequency tables should be greater among subjects with higher education and therefore hypothesized that the magnitude of the frequency effect should not be as marked within such a population as among subjects with a lesser educational level. A total of 40 neurologically healthy adults, half with an average of 18 years of formal education and the other half with an average of 11 years, participated in a lexical decision experiment. Results confirmed our hypothesis; that is, significant frequency effects on reaction times were obtained in both groups but this effect was of greater magnitude for the less educated as opposed to the more educated subgroup. The significance of this finding is discussed by reference to current models of word recognition.

Aging and the word frequency effect: a lexical decision investigation.

It is known that speed and accuracy in recognizing words are constrained by their frequency of occurrence ("frequency effect"). This study bears on the diachrony of the word frequency effect. Our postulates in this respect were (1) that a significant frequency effect should be present throughout adulthood, irrespective of age, and (2) that the magnitude of this effect should be greater among the elderly. Twenty young and 20 older healthy adults were submitted to a lexical decision experiment. Results confirmed our first postulate but invalidated the second one, that is, significant frequency effects were found in both groups but these effects were documented to be of identical magnitude. An attempt is made at explaining the latter result from a theoretical standpoint. The former is interpreted as further evidence that senescence (normal aging) does not interfere with passive, automatic and unconscious mental processes. Moreover, it is suggested that--if observed among otherwise apparently healthy elderly adults--modifications of the frequency effect might be taken as a cognitive marker of disease.