Working memory deficit in children with mathematical difficulties: a general or specific deficit?

This study examined whether children with mathematical difficulties (MDs) or comorbid mathematical and reading difficulties have a working memory deficit and whether the hypothesized working memory deficit includes the whole working memory system or only specific components. In the study, 31 10-year-olds with MDs and 37 10-year-olds with both mathematical and reading difficulties were compared with 47 age-matched and 50 younger controls (9-year-olds) on a number of working memory tasks. Compared with the age-matched controls, both groups of children with MDs performed worse on tasks tapping the central executive (e.g., visual matrix span) and the phonological loop (e.g., word span). More important, the MD group performed worse than the younger controls on the counting span task, whereas the group with comorbid mathematical and reading difficulties performed worse on the counting span task and the visual matrix span task. These findings provide support for the assumption that children with MDs have a working memory deficit. More specifically, children with MDs have a central executive deficit connected to concurrent processing and storage of numerical and visual information.     

Imbalanced word-reading profiles in eighth-graders

This current study introduced a new method to investigate the prevalence and correlates of significant imbalances in the relative accuracy with which eighth-graders read nonwords (e.g., prauma) and exception words (e.g., vaccine). Substantial proportions of students showed imbalanced word-reading profiles, but these were not strongly tied to differences in reading and spelling achievement. Of the students without reading difficulties, 19% had imbalanced word-reading profiles favoring exception words and 17% had imbalanced word-reading profiles favoring nonwords. Of the poor readers, 39% met the criterion for phonological dyslexia (with imbalanced word-reading profiles favoring exception words) and 14% met the criterion for surface dyslexia (with imbalanced word-reading profiles favoring nonwords) in relation to the eighth-grade benchmark readers, but the incidence of these types of dyslexia varied with verbal ability. Of the poor readers with normal verbal ability, 60% were classified as phonological dyslexics and none was classified as surface dyslexic. In students low in verbal ability, surface dyslexia was more common. However, when imbalanced word-reading profiles were defined in relation to fourth-grade reading-level controls, only 12 phonological dyslexics and 1 surface dyslexic were identified. Relatively few cases of either type of developmental dyslexia appeared to be "pure."     

Early precursors and enabling skills of reading acquisition

Research on early linguistic precursors and enabling skills of reading acquisition among young children is reviewed. Language development starts early in infancy when the child learns to categorize the speech sounds according to the pattern typical of the mother tongue. Equipped with these sound categories the child is ready to learn to segment words from the sound stream and to understand and to use words. The precise phonological representation of words will facilitate the important development of phonological awareness, a basic prerequisite for reading acquisition. This paper reviews some of my longitudinal research and training studies indicating the causal direction of the relation between phonological awareness and reading and includes some ongoing studies, where gender differences, socio‐economic factors, dose‐response‐effects and motivational factors are explored. Preventive and remedial implications of the findings are pointed out. Finally, the complexity of the causal relationships between different aspects of early language development, including genetic influences and later reading is pointed out.     

Toward a comprehensive view of the skills involved in word reading in Grades 4, 6, and 8

Research to date has proposed four main variables involved in reading development: phonological awareness, naming speed, orthographic knowledge, and morphological awareness. Although each of these variables has been examined in the context of one or two of the other variables, this study examines all four factors together to assess their unique contribution to reading. A sample of children in Grades 4, 6, and 8 (ages 10, 12, and 14 years) completed a battery of tests that included at least one measure of each of the four variables and two measures of reading accuracy. Phonological awareness, orthographic knowledge, and morphological awareness each contributed uniquely to real word and pseudoword reading beyond the other variables, whereas naming speed did not survive these stringent controls. The results support the sustained importance of these three skills in reading by older readers.     

Dyslexia and dyscalculia: Two learning disorders with different cognitive profiles

This study tests the hypothesis that dyslexia and dyscalculia are associated with two largely independent cognitive deficits, namely a phonological deficit in the case of dyslexia and a deficit in the number module in the case of dyscalculia. In four groups of 8- to 10-year-olds (42 control, 21 dyslexic, 20 dyscalculic, and 26 dyslexic/dyscalculic), phonological awareness, phonological and visual-spatial short-term and working memory, naming speed, and basic number processing skills were assessed. A phonological deficit was found for both dyslexic groups, irrespective of additional arithmetic deficits, but not for the dyscalculia-only group. In contrast, deficits in processing of symbolic and nonsymbolic magnitudes were observed in both groups of dyscalculic children, irrespective of additional reading difficulties, but not in the dyslexia-only group. Cognitive deficits in the comorbid dyslexia/dyscalculia group were additive; that is, they resulted from the combination of two learning disorders. These findings suggest that dyslexia and dyscalculia have separable cognitive profiles, namely a phonological deficit in the case of dyslexia and a deficient number module in the case of dyscalculia.     

Visual versus phonological abilities in Spanish dyslexic boys and girls

Phonological and visual theories propose different primary deficits as part of the explanation for dyslexia. Both theories were put to test in a sample of Spanish dyslexic readers. Twenty-one dyslexic and 22 typically-developing children matched on chronological age were administered phonological discrimination and awareness tasks and coherent motion perception tasks. No differences were found between groups on the coherent motion tasks, whereas dyslexic readers were impaired relative to controls on phonological discrimination tasks. Gender differences followed the opposite pattern, with no differences on phonological tasks, and dyslexic girls performing significantly worse than dyslexic boys in coherent motion perception. These results point to the importance of phonological deficits related to speech perception in Spanish, and to possible gender differences in the neurobiological bases for dyslexia.     

Semantic asymmetries are modulated by phonological asymmetries: Evidence from the disambiguation of homophonic versus heterophonic homographs

The present study investigated cerebral asymmetries in accessing multiple meanings of two types of homographs: homophonic homographs (e.g., bank) and heterophonic homographs (e.g., tear). Participants read homographs preceded by either a biasing or a non-biasing sentential context and performed a lexical decision on lateralized targets presented 150 ms after onset of the sentence-final ambiguous prime. Targets were either related to the dominant or the subordinate meaning of the preceding homograph or were unrelated to it. In the case of homophonic homographs – our results converge with previous findings: both activation and selection processes are faster in the LH than in the RH. Importantly, however, in the case of heterophonic homographs – opposite asymmetries were found. These results suggest that semantic asymmetries are modulated by phonology. They are discussed in the context of a model of functional architecture of reading in the two hemispheres in which orthography, phonology and semantics are fully interconnected in the LH, whereas in the RH, orthography and phonology are not directly connected, such that phonological processes are mediated by semantics.     

Phonological Activation in Multi-syllabic Sord Recognition

Three experiments were conducted to test the phonological recoding hypothesis in visual word recognition. Most studies on this issue have been conducted using mono-syllabic words, eventually constructing various models of phonological processing. Yet in many languages including English, the majority of words are multi-syllabic words. English includes words incorporating a silent letter in their letter strings (e.g., champane). Such words provide an opportunity for investigating the role of phonological information in multi-syllabic words by comparing them to words that do not have the silent letter in the corresponding position (e.g., passener). The performance focus is on the effects of removing letters from words with a silent letter and from words with a non-silent letter. Three representative lexical tasks—naming, semantic categorization, lexical decision—were conducted in the present study. Stimuli that excluded a silent letter (e.g., champa_ne) were processed faster than those that excluded a sounding letter (e.g., passen_er) in the naming (Experiment 1), the semantic categorization (Experiment 2), and the lexical decision task (Experiment 3). The convergent evidence from these three experiments provides seminal proof of phonological recoding in multi-syllabic word recognition. An erratum to this article can be found at     

Phonological,visual, and semantic coding strategies and children's short-term picture memory span

Three experiments addressed controversies in the previous literature on the development of phonological and other forms of short-term memory coding in children, using assessments of picture memory span that ruled out potentially confounding effects of verbal input and output. Picture materials were varied in terms of phonological similarity, visual similarity, semantic similarity, and word length. Older children (6/8-year-olds), but not younger children (4/5-year-olds), demonstrated robust and consistent phonological similarity and word length effects, indicating that they were using phonological coding strategies. This confirmed findings initially reported by Conrad (1971), but subsequently questioned by other authors. However, in contrast to some previous research, little evidence was found for a distinct visual coding stage at 4 years, casting doubt on assumptions that this is a developmental stage that consistently precedes phonological coding. There was some evidence for a dual visual and phonological coding stage prior to exclusive use of phonological coding at around 5–6 years. Evidence for semantic similarity effects was limited, suggesting that semantic coding is not a key method by which young children recall lists of pictures.     

Is phonological short-term memory related to phonological analysis stages in auditory sentence processing?

Despite extensive research, the role of phonological short-term memory (STM) during oral sentence comprehension remains unclear. We tested the hypothesis that phonological STM is involved in phonological analysis stages of the incoming words, but not in sentence comprehension per se. We compared phonological STM capacity and processing times for natural sentences and sentences containing phonetically ambiguous words. The sentences were presented for an auditory sentence anomaly judgement task and processing times for each word were measured. STM was measured via nonword and word immediate serial recall tasks, indexing phonological and lexicosemantic STM capacity, respectively. Significantly increased processing times were observed for phonetically ambiguous words, relative to natural stimuli in same sentence positions. Phonological STM capacity correlated with the size of this phonetic ambiguity effect. However, phonological STM capacity did not correlate with measures of later semantic integration processes while lexicosemantic STM did. This study suggests that phonological STM is associated with phonological analysis processes during sentence processing.