Double dissociations of word and number processing in auditory and written modalities: a case study

Meta-linguistic awareness skills in Chinese-speaking children with hyperlexia: A single-case study

Purpose

The aim of the study is to examine the meta-linguistic awareness skills contributing to reading aloud in a Chinese-speaking child with hyperlexia.

Methods

Case study approach was used with one case of hyperlexia (TYH) and two control groups: typically developing (TD) children matched for chronological age (CA) and TD children matched for mental ability (MA). A battery of phonological, morphological, and orthographic awareness skill tests were administered.

Results

Results from the modified t-test found that the hyperlexic child did not demonstrate advanced meta-linguistic awareness skills in comparison with the two control groups. On the contrary, TYH's morphological awareness skills were even lower than the CA control group. Also, in the orthographic awareness test, TYH demonstrated weaker knowledge of character structure and components than the two control groups although his ability in the recognition of real words is intact. In addition, the predictability of orthographic awareness skill was comparable to the CA group with predicted score showed no difference to his obtained score, while TYH achieved a significantly higher reading score than what his morphological awareness skills should predict with reference to TD children of similar age; as well as what his phonological awareness skill predict with reference to the MA group.

Conclusion

The findings suggest that TYH can achieve advanced reading ability with comparable phonological and orthographic awareness skill, despite his weakness in morphological awareness. It is concluded that the hyperlexic reading in Chinese might be achieved through the direct mapping between the whole character and the sound.

Delineating the cognitive-neural substrates of writing: a large scale behavioral and voxel based morphometry study

The current study investigated the cognitive and neural substrates that underpin writing ability. We explored similarities and differences in writing numbers and words and compared these to language and manual actions in a large group of sub-acute, stroke patients (n = 740). The behavioral data showed association and dissociation in the ability to write words and numbers. Comorbidities of writing deficits with both language and motor impairments were prevalent, with less than a handful showing deficits restricted to the writing tasks. A second analysis with a subset of patients (n = 267) explored the neural networks that mediate writing abilities. Lesion to right temporal contributed to writing words, while lesions to left postcentral contributed to writing numbers. Overlapping neural mechanisms included the bilateral prefrontal cortex, right inferior parietal, left middle occipital and the right cerebellum. With the former regions associated with error pattern typical to writing based on prior knowledge (the lexical route), while lesion to left MOG was associated with errors to the phonological (non-lexical) route. Using principle components extracted from the behavioral data, we showed that right prefrontal and right parietal contributed to the ability to use pen, while lesion to bilateral prefrontal, inferior temporal and cerebellum supported unique use of pen for writing. The behavioral and imaging data suggested that writing numbers and words primarily relied on overlapping cognitive and neural functions. Incidents of pure writing deficits, in the absence of motor or language deficits were rare. Nevertheless, the PCA and neural data suggested that writing abilities were associated with some unique neuro-cognitive functions, specifically dedicated to the use of pen and the ability to transform meaning to motor command.

Word deafness with preserved number word perception

We describe the performance of an aphasic individual, K.A., who showed a selective impairment affecting his ability to perceive spoken language, while largely sparing his ability to perceive written language and to produce spoken language. His spoken perception impairment left him unable to distinguish words or nonwords that differed on a single phoneme and he was no better than chance at auditory lexical decision or single spoken word and single picture matching with phonological foils. Strikingly, despite this profound impairment, K.A. showed a selective sparing in his ability to perceive number words, which he was able to repeat and comprehend largely without error. This case adds to a growing literature demonstrating modality-specific dissociations between number word and non-number word processing. Because of the locus of K.A.'s speech perception deficit for non-number words, we argue that this distinction between number word and non-number word processing arises at a sublexical level of representations in speech perception, in a parallel fashion to what has previously been argued for in the organization of the sublexical level of representation for speech production.

The number processing and calculation system: evidence from cognitive neuropsychology

INTRODUCTION

Cognitive neuropsychology focuses on the concepts of dissociation and double dissociation. The performance of number processing and calculation tasks by patients with acquired brain injury can be used to characterise the way in which the healthy cognitive system manipulates number symbols and quantities. The objective of this study is to determine the components of the numerical processing and calculation system.

METHODS

Participants consisted of 6 patients with acquired brain injuries in different cerebral localisations. We used Batería de evaluación del procesamiento numérico y el cálculo, a battery assessing number processing and calculation. Data was analysed using the difference in proportions test.

RESULTS

Quantitative numerical knowledge is independent from number transcoding, qualitative numerical knowledge, and calculation. Recodification is independent from qualitative numerical knowledge and calculation. Quantitative numerical knowledge and calculation are also independent functions.

CONCLUSIONS

The number processing and calculation system comprises at least 4 components that operate independently: quantitative numerical knowledge, number transcoding, qualitative numerical knowledge, and calculation. Therefore, each one may be damaged selectively without affecting the functioning of another. According to the main models of number processing and calculation, each component has different characteristics and cerebral localisations.