Brian Butterworth

Developmental dyscalculia and basic numerical capacities: a study of 8-9-year-old students.

Thirty-one 8- and 9-year-old children selected for dyscalculia, reading difficulties or both, were compared to controls on a range of basic number processing tasks. Children with dyscalculia only had impaired performance on the tasks despite high-average performance on tests of IQ, vocabulary and working memory tasks. Children with reading disability were mildly impaired only on tasks that involved articulation, while children with both disorders showed a pattern of numerical disability similar to that of the dyscalculic group, with no special features consequent on their reading or language deficits. We conclude that dyscalculia is the result of specific disabilities in basic numerical processing, rather than the consequence of deficits in other cognitive abilities.

Anterior cingulate activity during error and autonomic response

The contribution of anterior cingulate cortex (ACC) to human cognition remains unclear. The rostral (rACC) and dorsal (dACC) ACC cortex are implicated in tasks that require increased response control due to emotional and cognitive interference, respectively. However, both rACC and dACC are activated by conditions that induce changes in visceral arousal, suggesting that ACC supports a generation of integrated bodily responses. To clarify the relationship between purely cognitive and psychophysiological accounts of ACC function, we scanned 15 subjects using functional magnetic resonance imaging while they performed numerical versions of the Stroop task. To index autonomic arousal, we simultaneously measured pupil diameter. Performance errors accounted for most of the variance in a pupil-derived measure of evoked autonomic arousal. In analysis of the functional imaging data, activity within a region spanning rACC and dACC predicted trial-by-trial variation in autonomic response magnitude and was enhanced during error trials, shown using conjunction analyses. Activity within other loci within rACC predicted evoked autonomic arousal and showed sensitivity to errors but did not meet criteria for both. These data highlight the role of ACC in psychophysiological aspects of error processing and suggest that an interface exists within ACC between cognitive and biobehavioral systems in the service of response adaptation.

Dyscalculia: From brain to education

Recent research in cognitive and developmental neuroscience is providing a new approach to the understanding of dyscalculia that emphasizes a core deficit in understanding sets and their numerosities, which is fundamental to all aspects of elementary school mathematics. The neural bases of numerosity processing have been investigated in structural and functional neuroimaging studies of adults and children, and neural markers of its impairment in dyscalculia have been identified. New interventions to strengthen numerosity processing, including adaptive software, promise effective evidence-based education for dyscalculic learners.

Phonological dyslexia and dysgraphia in a highly literate subject: A developmental case with associated deficits of phonemic processing and awareness

This paper describes some aspects of reading and writing in a highly literate subject who has unusual difficulty in reading and spelling non-words. No cerebral trauma is indicated, and she performs at above average levels on standard tests of reading, spelling and cognitive ability. Only digit span is significantly impaired. Although auditory phoneme discrimination is normal, she performs poorly on aural tasks, like rhyme judgement and homophone matching, that require awareness of phonemic structure, and she is impaired at segmenting heard words into their component sounds. Tests of immediate memory confirm abnormal span and indicate a failure to use normal phonological coding in immediate recall. We argue that a deficit in phonological processing underlies impaired performance on tasks of reading, spelling and immediate memory.

Foundational numerical capacities and the origins of dyscalculia

One important cause of very low attainment in arithmetic (dyscalculia) seems to be a core deficit in an inherited foundational capacity for numbers. According to one set of hypotheses, arithmetic ability is built on an inherited system responsible for representing approximate numerosity. One account holds that this is supported by a system for representing exactly a small number (less than or equal to four4) of individual objects. In these approaches, the core deficit in dyscalculia lies in either of these systems. An alternative proposal holds that the deficit lies in an inherited system for sets of objects and operations on them (numerosity coding) on which arithmetic is built. I argue that a deficit in numerosity coding, not in the approximate number system or the small number system, is responsible for dyscalculia. Nevertheless, critical tests should involve both longitudinal studies and intervention, and these have yet to be carried out.

Hesitation and the production of verbal paraphasias and neologisms in jargon aphasia

Abstract Techniques of hesitation analysis taken from studies of normal speakers were applied to the speech of a jargon aphasic. Neologisms were found to follow pauses indicating a word-finding difficulty. Other language functions—phonology, morphology, and syntax—appeared unimpaired, and further analyses of the linguistic and temporal characteristics indicated a single functional disorder in which there is a failure in the mechanisms which associate word-sounds with word-meanings. The patient strategically adapts to this functional impairment by substituting a neologism when lexical search fails. The source of a large class of neologisms, it is hypothesized, is a device which quasirandomly combines English phonemes in a phonotactically regular way. The implications for recovery patterns in jargon aphasia are discussed; and the implications of this case for models of normal language production are explored.

Subject-verb agreement in Spanish and English: Differences in the role of conceptual constraints

This paper reports studies of subject-verb agreement errors with speakers of Spanish and English; we used a sentence completion task, first introduced by Bock and Miller (1991). In a series of four experiments, we assessed the role of semantic information carried by the sentential subject in the induction of subject-verb agreement errors. For Spanish speakers, a sentence preamble such as la etiqueta score las botellas (the label on the bottles), which is usually interpreted to denote several labels, induced more agreement errors than preambles that normally denote a single entity. This finding replicates previous research with Italian (Vigliocco et al., 1995). English speakers, on the other hand, were not sensitive to this semantic dimension, as was found earlier by Bock and Miller (1991). This cross-linguistic difference is discussed in the framework of a modified version of the computational model of grammatical encoding proposed by Kempen and Hoenkamp (1987). In this version of the model agreement is computed through a unification operation instead of feature-copying, allowing for an independent retrieval of agreement features from the conceptual representation for the subject and the verb. We propose that languages differ in the extent to which the selection of the verb is controlled by features on the subject and features from the conceptual representation.

Spared numerical abilities in a case of semantic dementia

We report a case study of a patient (IH) with a progressive impairment of semantic memory affecting all categories of knowledge apart from numbers. Pictorial material was better understood than words, but was still severely impaired. The selective preservation of nearly all aspects of numerical knowledge suggested that this domain might have different neuropsychological status from other aspects of semantic memory.

Toward a multiroute model of number processing: Impaired number transcoding with preserved calculation skills

This article describes a patient (S.A.M.), suffering from a progressive neurological degenerative condition of unknown origin, who showed a severe difficulty in number transcoding tasks. S.A.M. could recognize and understand arabic numerals and written number names, but he could neither read them aloud nor write them. However, he had a well maintained ability to perform oral and written calculations. The striking pattern of performance observed in S.A.M. suggests that deficits affecting the ability to produce arabic or verbal numerals can be specific to particular task demands. This observation cannot be easily accommodated by current models of numerical processing. A new multiroute model for numerical processing is proposed to account for S.A.M.s pattern of performance. This model adds asemantic transcoding pathways to the semantic processing mechanisms proposed by the M. McCloskey model.

Disorders of phonological encoding

Studies of phonological disturbances in aphasic speech are reviewed. It is argued that failure to test for error consistency in individual patients makes it generally improper to draw inferences about specific disorders of phonological encoding. A minimalist interpretation of available data on phonological errors is therefore proposed that involves variable loss of information in transmission between processing subsystems. Proposals for systematic loss or corruption of phonological information in lexical representations or in translation subsystems is shown to be inadequately grounded. The review concludes with some simple methodological prescriptions for future research.