Not everything is the same: some things are worse than others. A response to Tesak.
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Brain↗
Biomedical subjects
A Caramazza
Publications and source records attributed to A Caramazza.
Lexical organization of nouns and verbs in the brain.
The analysis of neuropsychological disorders of lexical processing has provided important clues about the general organization of the lexical system and the internal structure of the processing components. Reports of patients with selective dysfunction of specific semantic categories such as abstract versus concrete words, living things versus inanimate objects, animals, fruits and vegetables, proper names and so forth, support the hypothesis that the neural organization of the semantic processing component is organized in these categories. There are reports of selective dysfunction of the grammatical categories noun and verb, suggesting that a dimension of lexical organization is the grammatical class of words. But the results reported in these studies have not provided unambiguous evidence concerning two fundamental questions about the nature and the locus of this organization within the lexical system. Is the noun-verb distinction represented in the semantic or in the phonological and orthographic lexicons? Is grammatical-class knowledge represented independently of lexical forms or is it represented separately and redundantly within each modality-specific lexicon? Here we report the performance of two brain-damaged subjects with modality-specific deficits restricted principally (H.W.) or virtually only (S.J.D) to verbs in oral and written production, respectively. The contrasting performance suggests that grammatical-class distinctions are redundantly represented in the phonological and orthographic output lexical components.
Aphasia↗
Deficit to stimulus-centered, letter shape representations in a case of "unilateral neglect".
A brain-damaged subject is described whose pattern of performance in various reading tasks can be explained by proposing damage at a level of the word recognition process in which a representation with stimulus-centered, rather than retinal- or word-centered, coordinates is processed. Analysis of her reading performance as a function of topographical arrangement of letters, position of errors in the letter string, and the effects of letter spacing and of adding a prefix or suffix provide evidence not only for the existence of this level of representation (the letter-shape map in a model proposed by Caramazza and Hillis [3]), but also for specific assumptions about its functioning and structure.
Attention↗
Data, statistics, and theory: a comment on Bates, McDonald, MacWhinney, and Applebaum's "A maximum likelihood procedure for the analysis of group and individual data in aphasia research".
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Aphasia↗
Mechanisms for accessing lexical representations for output: evidence from a category-specific semantic deficit.
We report the performance of a neurologically impaired patient, JJ, whose oral reading of words exceeded his naming and comprehension performance for the same words--a pattern of performance that has been previously presented as evidence for "direct, nonsemantic, lexical" routes to output in reading. However, detailed analyses of JJ's reading and comprehension revealed two results that do not follow directly from the "direct route" hypothesis: (1) He accurately read aloud all orthophonologically regular words and just those irregular words for which he demonstrated some comprehension (as indicated by correct responses or within-category semantic errors in naming and comprehension tasks); and (2) his reading errors on words that were not comprehended at all (but were recognized as words) were phonologically plausible (e.g., soot read as "suit"). We account for these results by proposing that preserved sublexical mechanisms for converting print to sound, together with partially preserved semantic information, serve to mediate the activation of representations in the phonological output lexicon in the task of reading aloud. We present similar arguments for postulating an interaction between sublexical mechanisms and lexical output components of the spelling process.
Aged↗
Selective impairment of thematic role assignment in sentence processing.
We report the performance of a brain-damaged subject showing a particularly pure dissociation between impairment in processing thematic roles and spared ability to process the morphological structure of sentences. The thematic role processing impairment was observed in both comprehension and production of active and passive reversible sentences, although it was more severe for the latter sentence type. This pattern of performance poses interesting challenges for current conceptions of the nature of language breakdown in aphasia and for models of normal sentence processing.
Aphasia, Wernicke↗
Clinical syndromes are not God's gift to cognitive neuropsychology: a reply to a rebuttal to an answer to a response to the case against syndrome-based research.
In this paper we consider several issues about single-patient versus syndrome-based research in response to E. Zurif, D. Swinney, and J. A. Fodor's (1991, Brain and Cognition, 16, 198-210) criticism of A. Caramazza and W. Badecker (1989, Brain and Cognition, 10, 256-295). We argue that these authors have failed to provide convincing arguments in favor of syndrome-based research. In particular, we show that the specific example--a study by D. Swinney, E. Zurif, and J. Nicol (1989, Journal of Cognitive Neurosciences, 1, 25-37)--given by these authors as a demonstration of the usefulness of syndrome-based research to inform theories of normal language processing does not in fact serve this purpose.
Aphasia, Broca↗
Varieties of sentence comprehension deficits: a case study.
In recent publications, Grodzinsky (1984, 1986, 1990) has offered a new theory of the disruption of sentence comprehension in so-called agrammatic aphasics. In these works Grodzinsky contends that his account, which is based in various ways on the formal apparatus of current syntactic theory (Chomsky, 1981), is an accurate and explanatory characterization of the preserved language of all those who present with both agrammatic sentence production and asyntactic sentence comprehension. We argue that this claim is not in accord with the facts. We present a detailed case study of the sentence comprehension performance of a patient who is clinically categorized as agrammatic. This patient's performance on full and truncated passives, and on subject- and object-cleft sentences fails each of Grodzinsky's predictions for these sentence types. We argue that whether there exists any patient who does exhibit the predicted performance pattern is also in serious doubt.
Aphasia, Broca↗
The interaction of lexical and non-lexical processing mechanisms: evidence from anomia.
Patient SF presented with a selective deficit in naming, in the presence of normal auditory, visual and pictorial input processing, and of normal comprehension. The naming disorder was independent of input modality, and resulted in the inability to respond to low-frequency items. The analysis of the patient's performance in the repeated administration of the same set of pictures for oral naming and for written naming demonstrated that both tasks were disrupted to a similar extent--high consistency values were observed both across and within modality. Thus, the profile of the naming disorder observed in this patient was consistent with damage to phonological and orthographic output lexicons. SF's performance in reading and writing was apparently at odds with this account, as he was able to read aloud words with lexically-assigned stress, and to write to dictation words whose spelling is also determined lexically. The co-occurrence of the inability to activate output lexical representations in both oral and written picture naming, in the context of normal ability to activate the same representations in reading and in writing is consistent with the notion that phonological and orthographic output lexicons are distinct, but interact with nonlexical conversion mechanisms.
Anomia↗
Category-specific naming and comprehension impairment: a double dissociation.
We describe 2 neurologically impaired patients with lesions involving primarily the left temporal lobe, whose production and comprehension of words in the semantic category of animals were disproportionately spared in 1 case and disproportionately impaired in the other, in comparison to performance with other common categories. This double dissociation provides neurally based evidence for the view that lexical-semantic information is organized categorically.
Aged↗
Spatial representation of words in the brain implied by studies of a unilateral neglect patient.
Reading and writing require access to stored knowledge about the spelling of words. Presumably, we recognize chair but not chare or chiar as a word of English, and similarly would write 'chair' but not 'chare' or 'chiar', because we access orthographic representations that specify the identity and the order of the graphemes (abstract letter representations) that comprise the spelling of words. Thus, a fundamental problem concerns the content and structure of the hypothesized orthographic representations, and how information about grapheme order is represented and processed. We present evidence from a brain-damaged patient (N.G.) with unilateral neglect that this information is coded spatially. Unilateral neglect is a disorder clinically characterized by the inability to perceive or respond to stimuli presented to the side contralateral to the site of lesion, despite the absence of significant sensory or motor deficits. The patient made reading and spelling errors only on the right half of words, regardless of length. Furthermore, she produced the same pattern of errors in reading and spelling, irrespective of the topographic arrangement of stimuli in reading (horizontal, vertical or mirror-reversed words) and of the type of response in spelling (written, oral or backward oral spelling). This pattern of performance suggests that order information in orthographic representations is coded spatially in a word-centred coordinate system; that is, in a spatially defined coordinate frame whose centre corresponds to the midpoint of a canonical, orientation-invariant representation of the word and not the midpoint of the word stimulus.
Aged↗
Lexical morphology and its role in the writing process: evidence from a case of acquired dysgraphia.
A case of acquired dysgraphia is presented in which the deficit is attributed to an impairment at the level of the Graphemic Output Buffer. It is argued that this patient's performance can be used to identify the representational character of the processing units that are stored in the Orthographic Output Lexicon. In particular, it is argued that the distribution of spelling errors and the types of lexical items which affect error rates indicate that the lexical representations passed from the lexical output system to the Graphemic Output Buffer correspond to the productive morphemes of the language.
Agraphia↗
The structure of graphemic representations.
The analysis of the spelling performance of a brain-damaged dysgraphic subject is reported. The subject's spelling performance was affected by various graphotactic factors, such as the distinction between consonant and vowel and graphosyllabic structure. For example, while the subject produced many consonant and vowel deletion errors when these were part of consonant and vowel clusters, respectively (e.g., sfondo----sondo; giunta----gunta), deletions were virtually never produced for single consonants flanked by two vowels (e.g., onesto----oesto) or for single vowels flanked by two consonants (e.g., tirare----trare). The demonstration that graphosyllabic factors affect spelling performance disconfirms the hypothesis that graphemic representations consist simply of linearly ordered sets of graphemes. It is concluded that graphemic representations are multidimensional structures: one dimension specifies the grapheme identities that comprise the spelling of a word; a second dimension specifies the consonant/vowel status of the graphemes; a third dimension represents the graphosyllabic structure of the grapheme string; and, a fourth dimension provides information about geminate features.
Agraphia↗
Where do semantic errors come from?
We report the performance of two brain-damaged subjects (RGB and HW) whose frequent errors in spoken production are nearly always semantically related to the target word. Both subjects show similar, high rates of these "semantic" errors in oral naming and oral reading; yet neither subject makes semantic errors in comparable written tasks. Further, results of a variety of lexical tasks with the same stimuli demonstrate unimpaired comprehension of printed or spoken words, including those that are orally produced as semantic errors. These patterns of performance are interpreted as resulting from damage to the phonological output lexicon. The postulated deficit is contrasted to the hypothesis of impairment to the lexical-semantic component, required to explain performance by brain-damaged subjects described elsewhere who make seemingly identical types of oral production errors to those of RGB and HW, but, in addition, make comparable errors in writing and comprehension tasks.
Brain Damage, Chronic↗
The graphemic buffer and attentional mechanisms.
Two patients with acquired dysgraphia were reported. The patients' performance in various written and oral spelling tasks converge in support of the hypothesis that they have selective damage, within the spelling system, to the Graphemic Buffer. Although the patients present with comparable patterns of error types, they differ in the distribution of errors as a function of letter position in words. The patients' patterns of errors are compared to previously reported patterns of spelling errors in dysgraphic patients and are discussed in terms of hypothesized mechanisms that operate on the representations that are stored in the Graphemic Buffer.
Agraphia↗
Variation in the pattern of omissions and substitutions of grammatical morphemes in the spontaneous speech of so-called agrammatic patients.
We describe the patterns of omissions (and substitutions) of freestanding grammatical morphemes and the patterns of substitutions of bound grammatical morphemes in 20 so-called agrammatic patients. Extreme variation was observed in the patterns of omissions and substitutions of grammatical morphemes, both in terms of the distribution of errors for different grammatical morphemes as well as in terms of the distribution of omissions versus substitutions. Results are discussed in the context of current debates concerning the possibility of a theoretically motivated distinction between the clinical categories of agrammatism and paragrammatism and, more generally, concerning the theoretical usefulness of any clinical category. The conclusion is reached that the observed heterogeneity in the production of grammatical morphemes among putatively agrammatic patients renders the clinical category of agrammatism, and by extension all other clinical categories from the classical classification scheme (e.g., Broca's aphasia, Wernicke's aphasia, and so forth) to more recent classificatory attempts (e.g., surface dyslexia, deep dysgraphia, and so forth), theoretically useless.
Adult↗
The disruption of sentence production: some dissociations.
A patient (M.L.) with selective disruption of sentence production is described. M.L.'s sentence production performance is characterized by the omission (and occasional substitution) of free-standing and bound grammatical morphemes. In contrast to her impaired sentence production performance, M.L. has no difficulties in sentence comprehension or production of single words including functors. Her performance is interpreted as reflecting a functional lesion to the positional level of sentence production.
Agraphia↗
Patient classification in neuropsychological research.
In a number of papers we have been concerned with the type of inferences that are legitimate in "experiments of nature" where the experimenter does not and cannot control the modifications to the cognitive system that are introduced by brain damage. We have argued that in such cases very restrictive conditions must be met in order to be able to draw valid inferences about the structure of normal cognitive mechanisms. Two consequences of these conditions are (1) patient classification into syndrome types (e.g., phonological dysgraphia, agrammatism, and so forth) can play no useful role in research concerned with issues about the structure of normal cognitive functioning or its dissolution under conditions of brain damage; and (2) only single-patient studies allow valid inferences about the structure of cognitive mechanisms from the analysis of impaired performance. Zurif, Gardner, and Brownell (1989, Brain and Cognition, 10, 237-255) have taken exception to our conclusions and propose to show the limitations of our arguments. In this paper we respond to their criticisms.
Aphasia↗