Rose K. Vukovic

The Double-Deficit Hypothesis A Comprehensive Analysis of the Evidence

The double-deficit hypothesis of developmental dyslexia proposes that deficits in phonological processing and naming speed represent independent sources of dysfunction in dyslexia. The present article is a review of the evidence for the double-deficit hypothesis, including a discussion of recent findings related to the hypothesis. Studies in this area have been characterized by variability in methodology— how dyslexia is defined and identified, and how dyslexia subtypes are classified. Such variability sets limitations on the extent to which conclusions may be drawn with respect to the double-deficit hypothesis. Furthermore, the literature is complicated by the persistent finding that measures of phonological processing and naming speed are significantly correlated, resulting in a statistical artifact that makes it difficult to disentangle the influence of naming speed from that of phonological processing. Longitudinal and intervention studies of the double-deficit hypothesis are needed to accumulate evidence that investigates a naming speed deficit that is independent of a phonological deficit for readers with dyslexia. The existing evidence does not support a persistent core deficit in naming speed for readers with dyslexia.

The Language of Mathematics: Investigating the Ways Language Counts for Children's Mathematical Development.

This longitudinal study examined how language ability relates to mathematical development in a linguistically and ethnically diverse sample of children from 6 to 9 years of age. Study participants were 75 native English speakers and 92 language minority learners followed from first to fourth grades. Autoregression in a structural equation modeling (SEM) framework was used to evaluate the relation between childrens language ability and gains in different domains of mathematical cognition (i.e., arithmetic, data analysis/probability, algebra, and geometry). The results showed that language ability predicts gains in data analysis/probability and geometry, but not in arithmetic or algebra, after controlling for visual-spatial working memory, reading ability, and sex. The effect of language on gains in mathematical cognition did not differ between language minority learners and native English speakers. These findings suggest that language influences how children make meaning of mathematics but is not involved in complex arithmetical procedures whether presented with Arabic symbols as in arithmetic or with abstract symbols as in algebraic reasoning. The findings further indicate that early language experiences are important for later mathematical development regardless of language background, denoting the need for intensive and targeted language opportunities for language minority and native English learners to develop mathematical concepts and representations.

Naming speed deficits in adults with reading disabilities: A test of the double-deficit hypothesis

The present study investigated the persistent nature of naming speed deficits within the context of the double-deficit hypothesis in a university sample of adults with reading disabilities (RD). Twenty-five university students with RD were compared to 28 typically achieving readers on measures of reading skill, phonological processing, and naming speed. The results indicated that both naming speed and phonological processing deficits characterized the RD group. In a regression analysis, neither naming speed nor phonological processing were important variables in explaining comprehension when reading rate was in the model. The results of the present study are mixed at best and are consistent with earlier conclusions that support for the double-deficit hypothesis of dyslexia remains limited.

Contributions of domain-general cognitive resources and different forms of arithmetic development to pre-algebraic knowledge.

The purpose of this study was to investigate the contributions of domain-general cognitive resources and different forms of arithmetic development to individual differences in pre-algebraic knowledge. Children (n = 279, mean age = 7.59 years) were assessed on 7 domain-general cognitive resources as well as arithmetic calculations and word problems at start of 2nd grade and on calculations, word problems, and pre-algebraic knowledge at end of 3rd grade. Multilevel path analysis, controlling for instructional effects associated with the sequence of classrooms in which students were nested across Grades 2-3, indicated arithmetic calculations and word problems are foundational to pre-algebraic knowledge. Also, results revealed direct contributions of nonverbal reasoning and oral language to pre-algebraic knowledge, beyond indirect effects that are mediated via arithmetic calculations and word problems. By contrast, attentive behavior, phonological processing, and processing speed contributed to pre-algebraic knowledge only indirectly via arithmetic calculations and word problems.

Mathematics Difficulty with and without Reading Difficulty: Findings and Implications from a Four-Year Longitudinal Study

An overarching question guided this study: What is mathematics difficulty (MD) independent of reading difficulty (RD)? The sample included 203 children whom the researchers followed from kindergarten to third grade. The researchers used latent growth modeling to investigate the relationship between MD and measures of working memory, short-term memory, cognitive processing speed, early numerical skills, and phonological processing, independent of reading. Two main findings emerged: (a) deficits in early numerical skills were a defining feature of MD with or without RD, and (b) early numerical skills and phonological processing influenced growth in mathematics from kindergarten to third grade. These results indicate that future MD research should focus on numerical and language-based skills, including whether the mathematics disorder in MD—specific or otherwise—reflects underlying language and/or numerical deficits.

From Parental Involvement to Children's Mathematical Performance: The Role of Mathematics Anxiety.

This study examined whether childrens mathematics anxiety serves as an underlying pathway between parental involvement and childrens mathematics achievement. Participants included 78 low-income, ethnic minority parents and their children residing in a large urban center in the northeastern United States. Parents completed a short survey tapping several domains of parental involvement, and children were assessed on mathematics anxiety, whole number arithmetic, word problems, and algebraic reasoning. Research Findings: The results indicated that parents influence childrens mathematics achievement by reducing mathematics anxiety, particularly for more difficult kinds of mathematics. Specifically, the mediation analyses demonstrated that parental home support and expectations influenced childrens performance on word problems and algebraic reasoning by reducing childrens mathematics anxiety. Mathematics anxiety did not mediate the relationship between home support and expectations and whole number arithmetic. Practice or Policy: Policies and programs targeting parental involvement in mathematics should focus on home-based practices that do not require technical mathematical skills. Parents should receive training, resources, and support on culturally appropriate ways to create home learning environments that foster high expectations for childrens success in mathematics.

Mathematics Anxiety in Young Children: An Exploratory Study

This study explored the nature of mathematics anxiety in a sample of 106 ethnically and linguistically diverse first-grade students. Although much is known about mathematics anxiety in older children and adults, little is known about when mathematics anxiety first emerges or its characteristics in young children. Results from exploratory factor analysis indicated that mathematics anxiety in first grade is a multidimensional construct encompassing negative reactions, numerical confidence, and worry. Negative reactions were related specifically to foundational mathematical concepts whereas numerical confidence was related specifically to computation skill; worry was not related to any outcome. Levels of mathematics anxiety did not differ by sex or language background. Overall, negative reactions and numerical confidence were found to be the most salient dimensions of mathematics anxiety in this sample.

Components and Context Exploring Sources of Reading Difficulties for Language Minority Learners and Native English Speakers in Urban Schools

Drawing on the cognitive and ecological domains within the componential model of reading, this longitudinal study explores heterogeneity in the sources of reading difficulties for language minority learners and native English speakers in urban schools. Students (N = 150) were followed from first through third grade and assessed annually on standardized English language and reading measures. Structural equation modeling was used to investigate the relative contributions of code-related and linguistic comprehension skills in first and second grade to third grade reading comprehension. Linguistic comprehension and the interaction between linguistic comprehension and code-related skills each explained substantial variation in reading comprehension. Among students with low reading comprehension, more than 80% demonstrated weaknesses in linguistic comprehension alone, whereas approximately 15% demonstrated weaknesses in both linguistic comprehension and code-related skills. Results were remarkably similar for the language minority learners and native English speakers, suggesting the importance of their shared socioeconomic backgrounds and schooling contexts.

Context matters: The interrelatedness of early literacy skills, developmental health, and community demographics

Whereas the great majority of literacy research has been focused at the child level, this study examined the relationship between early literacy rates, developmental health of the population, and demographics in 23 school communities. The results showed that school-level literacy scores were related to the physical, social, and emotional maturity of the kindergarten population, as well as community demographics, including the proportion of families in each school catchment area living below the low income cutoff, the proportion of single-parent families, and the community 5-year mobility rate. Furthermore, the proportion of children at risk for literacy difficulties varied systematically by school, ranging from 0% to 44%; this risk was strongly related to developmental health and to demographics of the school community. The implications for models of early identification and corresponding intervention programs for at-risk children are discussed.