It is widely recognized that individuals with dyslexia have difficulties with word reading "and" spelling, and individuals with reading comprehension difficulties have low vocabulary knowledge. However, little is known about the extent to which spelling and vocabulary are informative of reading difficulties. In the present study, we…

How prevalent is dyslexia? A definitive answer to this question has been elusive because of the continuous distribution of reading performance and predictors of dyslexia and because of the heterogeneous nature of samples of poor readers. Samples of poor readers are a mixture of individuals whose reading is consistent with or expected based on…

The Computer-based Orthographic Processing Assessment (COPA) is a newly developed assessment to measure orthographic processing skills, including rapid perception, access, differentiation, correction, and arrangement. In this study, cognitive diagnostic models were used to test if the dimensionality of the COPA conforms to theoretical expectation,…

Attention is correlated with reading, but the extent to which behavioral ratings and sustained attention relate to reading skills is unclear. We assessed 245 fourth and fifth grade struggling readers (mean age = 10.3 years) on behavioral ratings of attention, sustained attention, and reading over a school year. Contributions of behavioral ratings…

Many states now mandate early screening for dyslexia, but vary in how they address these mandates. There is confusion about the nature of screening versus diagnostic assessments, risk versus diagnosis, concurrent versus predictive validity, and inattention to indices of classification accuracy as the basis for determining risk. To help define what…

This experimental study examined the efficacy of a multicomponent reading intervention compared to a business-as-usual comparison condition on the reading comprehension and content area vocabulary outcomes of adolescent students with low reading comprehension. We randomly assigned 9th-grade students with low reading comprehension to a…

Orthographic processing -- the ability to perceive, access, differentiate, and manipulate orthographic knowledge -- is essential when learning to recognize words. Despite its critical importance in literacy acquisition, the field lacks a tool to assess this essential cognitive ability. The goal of this study was to design a computer-based…

This study investigated the prevalence of latent classes at risk for reading or math disabilities in elementary-age children whose first language is Spanish. To this end, children (N = 394) in Grades 1, 2, and 3 were administered a battery of vocabulary, reading, math, and cognitive measures in both Spanish and English. Three important findings…

This study investigated the prevalence and stability of latent classes among elementary-aged English learning (EL) children whose first language is Spanish. To this end, EL children (N = 267) in Grades 1, 2, and 3 at Wave 1 (Year 1) were administered a battery of vocabulary, reading, math, and cognitive measures (short-term memory, working memory,…

We evaluated the impact of teaching complex grapheme-phoneme correspondences (GPC) derived from the Simplicity Principle to at-risk poor readers in Grade 2 classrooms, using a two-arm dual site matched control trial intervention. Poor word readers (n = 149) were allocated to either a) Simplicity GPC (n= 79) or b) Letter-Name Control (n= 70) small…

A substantial body of research has demonstrated the efficacy of early writing interventions that target skills and composing processes; however, much less is known about the effectiveness of classroom writing instruction outside of the context of an intervention. The goal of this study was to investigate if writing instruction and student practice…

Gough and Tunmer's (1986) simple view of reading (SVR) proposed that reading comprehension (RC) is a function of language comprehension (LC) and word recognition/decoding. Braze et al. (2007) presented data suggesting an extension of the SVR in which knowledge of vocabulary (V) affected RC over and above the effects of LC. Tunmer and Chapman…

The purpose of this study was to investigate the impact of inference making, decoding, memory, and vocabulary on reading comprehension among 7th- through 12th-grade struggling readers with varying levels of inattention and hyperactivity. We categorized a group of 414 struggling readers into 3 groups based on results from factor mixture modeling:…

Competent reading requires various skills beyond those for basic word reading (i.e., core language skills, rapid naming, phonological processing). Contributing "higher-level" or domain-general processes include information processing speed and executive functions (working memory, strategic problem solving, attentional switching).…

Montessori classrooms vary in the degree to which they adhere to Maria Montessori's model, including in the provision of materials. Specifically, some classrooms use only Montessori materials, whereas others supplement the Montessori materials with commercially available materials like puzzles and games. A prior study suggested such…