Investigation of dyslexia and SLI risk variants in reading- and language-impaired subjects

Dyslexia (or reading disability) and specific language impairment (or SLI) are common childhood disorders that show considerable co-morbidity and diagnostic overlaps and have been suggested to share some genetic aetiology. Recently, genetic risk variants have been identified for SLI and dyslexia enabling the direct evaluation of possible shared genetic influences between these disorders. In this study we investigate the role of variants in these genes (namely MRPL19/C20RF3, ROBO1, DCDC2, KIAA0319, DYX1C1, CNTNAP2, ATP2C2 and CMIP) in the aetiology of SLI and dyslexia. We perform case–control and quantitative association analyses using measures of oral and written language skills in samples of SLI and dyslexic families and cases. We replicate association between KIAA0319 and DCDC2 and dyslexia and provide evidence to support a role for KIAA0319 in oral language ability. In addition, we find association between reading-related measures and variants in CNTNAP2 and CMIP in the SLI families.

An investigation of reading ability and visual function with eccentric visual field

This study investigated the detrimental effect of central field loss (CFL) on reading ability and general visual function. The aim was to improve the understanding of reading with eccentric retina in order that reading performances of individuals with CFL may be maximised. To improve visual ability of individuals with CFL, it is important to be able to accurately measure the outcome of any intervention. Various methods for determining visual function were therefore compared with perceived visual performance (as measured with a quality of life questionnaire) before and after surgical removal of choroidal new vessels (CNV) in macular disease patients. The results highlight the importance of low contrast measures (low contrast visual acuity and contrast sensitivity) when investigating perceived reading performance. Reading speed was found to be important for reflecting changes in general visual quality of life. Potential causes for reduced peripheral reading ability were investigated using both normally sighted and CFL subjects. For normally sighted subjects reading eccentrically with rapid serial visual presentation (RSVP) text, the inferior visual field was a better position (in terms of reading speed) for the presentation of the text. The size of the visual span was found to reduce with increasing eccentricity of fixation, providing a potential reason for reduced peripheral reading performances. The investigation of the ability to use context when reading with peripheral retina resulted in conflicting results. Studies in this thesis found both a reduction and no reduction in the ability of the peripheral retina to utilise context compared to the fovea. Individuals with long-term CFL showed no improvement in peripheral reading ability over that found for normally sighted subjects reading at the same eccentricity.

Interval timing in children:effects of auditory and visual pacing stimuli and relationships with reading and attention variables

Motor timing tasks have been employed in studies of neurodevelopmental disorders such as developmental dyslexia and ADHD, where they provide an index of temporal processing ability. Investigations of these disorders have used different stimulus parameters within the motor timing tasks which are likely to affect performance measures. Here we assessed the effect of auditory and visual pacing stimuli on synchronised motor timing performance and its relationship with cognitive and behavioural predictors that are commonly used in the diagnosis of these highly prevalent developmental disorders. Twenty- one children (mean age 9.6 years) completed a finger tapping task in two stimulus conditions, together with additional psychometric measures. As anticipated, synchronisation to the beat (ISI 329 ms) was less accurate in the visually paced condition. Decomposition of timing variance indicated that this effect resulted from differences in the way that visual and auditory paced tasks are processed by central timekeeping and associated peripheral implementation systems. The ability to utilise an efficient processing strategy on the visual task correlated with both reading and sustained attention skills. Dissociations between these patterns of relationship across task modality suggest that not all timing tasks are equivalent.

Speech and non-speech stimuli in the prediction of early reading skills:the influence of processing demands and response-type

Purpose: Both phonological (speech) and auditory (non-speech) stimuli have been shown to predict early reading skills. However, previous studies have failed to control for the level of processing required by tasks administered across the two levels of stimuli. For example, phonological tasks typically tap explicit awareness e.g., phoneme deletion, while auditory tasks usually measure implicit awareness e.g., frequency discrimination. Therefore, the stronger predictive power of speech tasks may be due to their higher processing demands, rather than the nature of the stimuli. Method: The present study uses novel tasks that control for level of processing (isolation, repetition and deletion) across speech (phonemes and nonwords) and non-speech (tones) stimuli. 800 beginning readers at the onset of literacy tuition (mean age 4 years and 7 months) were assessed on the above tasks as well as word reading and letter-knowledge in the first part of a three time-point longitudinal study. Results: Time 1 results reveal a significantly higher association between letter-sound knowledge and all of the speech compared to non-speech tasks. Performance was better for phoneme than tone stimuli, and worse for deletion than isolation and repetition across all stimuli. Conclusions: Results are consistent with phonological accounts of reading and suggest that level of processing required by the task is less important than stimuli type in predicting the earliest stage of reading.

The neural correlates of reading impairment in adults with developmental dyslexia:evidence from fMRI between group analyses and an fMRI multiple-case study

The goal of this project was to investigate the neural correlates of reading impairment in dyslexia as hypothesised by the main theories – the phonological deficit, visual magnocellular deficit and cerebellar deficit theories, with emphasis on individual differences. This research took a novel approach by: 1) contrasting the predictions in one sample of participants with dyslexia (DPs); 2) using a multiple-case study (and between-group comparisons) to investigate differences in BOLD between each DP and the controls (CPs); 3) demonstrating a possible relationship between reading impairment and its hypothesised neural correlates by using fMRI and a reading task. The multiple-case study revealed that the neural correlates of reading in dyslexia in all cases are not in agreement with the predictions of a single theory. The results show striking individual differences - even, where the neural correlates of reading in two DPs are consistent with the same theory, the areas can differ. A DP can exhibit under-engagement in an area in word, but not in pseudoword reading and vice versa, demonstrating that underactivation in that area cannot be interpreted as a ‘developmental lesion’. Additional analyses revealed complex results. Within-group analyses between behavioural measures and BOLD showed correlations in the predicted regions, areas outside ROI, and lack of correlations in some predicted areas. Comparisons of subgroups which differed on Orthography Composite supported the MDT, but only for Words. The results suggest that phonological scores are not a sufficient predictor of the under-engagement of phonological areas during reading. DPs and CPs exhibited correlations between Purdue Pegboard Composite and BOLD in cerebellar areas only for Pseudowords. Future research into reading in dyslexia should use a more holistic approach, involving genetic and environmental factors, gene by environment interaction, and comorbidity with other disorders. It is argued that multidisciplinary research, within the multiple-deficit model holds significant promise here.

Early predictors of phonological and morphological awareness and the link with reading:evidence from children with different patterns of early deficit

This study examines the contribution of early phonological processing (PP) and language skills on later phonological awareness (PA) and morphological awareness (MA), as well as the links among PA, MA, and reading. Children 4-6 years of age with poor PP at the start of school showed weaker PA and MA 3 years later (age 7-9), regardless of their language skills. PA and phonological and morphological strategies predict reading accuracy, whereas MA predicts reading comprehension. Our findings suggest that children with poor early PP are more at risk of developing deficits in MA and PA than children with poor language. They also suggest that there is a direct link between PA and reading accuracy and between MA and reading comprehension that cannot be accounted for by strategy use at the word level.

The effects of required/sequenced preparatory courses on academic success and retention at a community college

This dissertation had two purposes: first, to analyze how required sequenced college preparatory courses in mathematics, reading, and writing affect students' academic success and, second, to add to a theoretical model for predicting student retention at a community college. Grade point average, number of degree credits earned, and re-enrollment rate were measured as determinants of academic success. The treatment group had a significantly higher grade point average than the control group. There was no significant difference in the number of degree credits earned or re-enrollment rate for the groups. A series of logistic regressions used the independent variables E-ASSET scores in math, reading, and writing; number of college prep areas required; credits earned; grade point average; students' status; academic restrictions/required course sequencing; sex; race; and socio-economic status to determine the predictor variables for retention. The academic variable that showed the greatest potential as a predictor for retention was grade point average. Overall, receiving financial aid was the greatest predictor for re-enrollment. For a financial aid recipient the odds of re-enrollment were 2.70 times more likely than if no financial aid was received.

The effects of bilingual and monolingual reading videos on story recall with students who are deaf and hard of hearing

The purpose of this study is to investigate the effects of bilingual and monolingual videos on the reading comprehension of students with significant hearing impairments and/or deafness. Children with and without hearing losses need reading programs in which comprehension of meaning is the primary goal. This can occur only when print is represented in meaningful context, allowing children to create meaning from their own experience, background, and knowledge of language.^ Investigated in this study was whether students with significant hearing losses comprehended more information in a bilingual or monolingual instructional video format. There were three instructional videos produced: (a) the bilingual video which incorporated American Sign Language (ASL) with standard English captions, (b) a monolingual English video with standard English captions only, and (c) a monolingual ASL-only video. It was hypothesized that the effects of English captioning with ASL might serve as a bridge during instruction, increasing reading comprehension and written English for students. It was further hypothesized that this would allow students to integrate their own ASL knowledge to the printed text to construct meaning.^ Four separate analyses were conducted to see if the hypothesis was supported by the findings. However, all results indicated that there were no significant differences in students' written measures of reading comprehension recall across any of the three presentations of information (two monolingual and one bilingual condition). There were seven variables (word identification, word recall, sentence recall, story recall, written passage theme, written passage word count, and number of mature words) used to evaluate reading comprehension recall. No variable, either individually or grouped, demonstrated a significant difference between monolingual or bilingual instruction. ^

Effect of the Florida A+ Plan on curriculum and instruction in Title I public elementary schools

The purpose of this research was to study the effect of the Florida A+ Plan accountability program on curriculum and instruction in four Title I public elementary schools in the Miami-Dade County Public Schools system. It focused on the experiences of the school principals and the classroom teachers of the four schools as they related to curriculum and instruction. The study included an analysis of the school improvement plans in curriculum and instruction for each school during the school years 1998-2004. ^ The study was conducted in the format of interviews with the school principals and principal selected classroom teachers who taught third, fourth, or fifth grade during the first six years of the Florida A+ Plan. The analysis of the school improvement plans focused on the implementation of curriculum and instruction for each of the four schools. It focused on the goals and measurable objectives selected by each school to improve its instructional program in the academic subjects of reading, mathematics, writing, and science. ^ The findings indicated that under the pressure to improve their school grade on the Florida A+ Plan, each of the target schools, based on individual needs assessments, and restructured their instructional program each school year as documented in their school improvement plans. They altered their programs by analyzing student performance data to realign curriculum and instruction. The analysis of the interviews with the principals and the teachers showed that each school year they restructured their program to align it with the FCAT content. This realigning was a collaborative effort on the part of the administration and the instructional staff. ^

An analysis of student and instructor perceptions of students' writing skills at the university level

This study examined university students' writing skills as perceived by university students and their English instructors. The goal of the study was to provide English instructors with objective, quantified information about writing perceptions from both the students' and instructors' viewpoints. ^ A survey instrument was developed based on a survey instrument created by Newkirk, Cameron, and Selfe (1977) to identify instructors' perceived knowledge of student writing skills. The present study used a descriptive statistical design. It examined five writing skill areas: attitude, content, grammar and mechanics, literary considerations, and the writing process through a questionnaire completed by a convenience sample of summer and fall admitted freshmen who were enrolled in Essay Writing and Freshman Composition courses and English Department instructors at a large South Florida public university. ^ The study consisted of five phases. The first phase was modifying of the Newkirk, Cameron, and Selfe (1977) questionnaire. Two versions of the revised survey were developed - one for instructors and one for students. The second phase was pilot testing the questionnaire for evaluation of administration and scoring. The third phase was administering the questionnaire to 1,280 students and 48 instructors. The fourth phase was analyzing the data. The study found a significant difference in the perceptions of students and instructors in all areas of writing skills examined by the survey. Responses to 29 of 30 questions showed that students felt they had better attitudes toward writing and better writing skills than instructors thought. ^ The final phase was developing recommendations for practice. Based on findings and theory and empirical evidence drawn from the fields of adult education and composition research, learner-centered, self-directed curriculum guidelines are offered. ^ By objectively quantifying student and instructor perceptions of students' writing skills, this study contributes to a growing body of literature that: (a) encourages instructors to acknowledge the perception disparities between instructors and students; (b) gives instructors a better understanding of how to communicate with students; and (c) recommends the development of new curriculum, placement tests, and courses that meet the needs of students and enables English instructors to provide meaningful instruction. ^

Comparison of repeated and two non-repeated readings conditions on reading abilities of students with emotional and/or behavioral disabilities

Students with emotional and/or behavioral disorders (EBD)present considerable academic challenges along with emotional and/or behavioral problems. In terms of reading, these students typically perform one-to-two years below grade level (Kauffman, 2001). Given the strong correlation between reading failure and school failure and overall success (Scott & Shearer-Lingo, 2002), finding effective approaches to reading instruction is imperative for these students (Staubitz, Cartledge, Yurick, & Lo, 2005). This study used an alternating treatments design to comparethe effects of three conditions on the reading fluency, errors, and comprehension of four, sixth-grade students with EBD who were struggling readers. Specifically, the following were compared: (a) Repeated readings in which participants repeatedly read a passage of about 100-150 words, three times, (b) Non-repeated readings in which participants sequentially read an original passage of about 100-150 words once, and (c) Equivalent non-repeated readings in which participants sequentially read a passage of about 300-450 words, equivalent to the number of words in the repeated readings condition. Also examined were the effects of the three repeated readings practice trials per sessions on reading fluency and errors. The reading passage difficulty and length established prior to commencing were used for all participants throughout the standard phase. During the enhanced phase, the reading levels were increased 6 months for all participants, and for two (the advanced readers), the length of the reading passages was increased by 50%, allowing for comparisons under more rigorous conditions. The results indicate that overall repeated readings had the best outcome across the standard and enhanced phases for increasing readers’ fluency, reducing their errors per minute, and supporting fluency answers to literal comprehension questions correctly as compared to non-repeated and equivalent non-repeated conditions. When comparing nonrepeated and equivalent non-repeated readings,there were mixed results. Under the enhanced phases, the positive effects of repeated readings were more demonstrative. Additional research is needed to compare the effects of repeated and equivalent non-repeated readings across other populations of students with disabilities or varying learning styles. This research should include collecting repeated readings practice trial data for fluency and errors to further analyze the immediate effects of repeatedly reading a passage.

An examination of the effects of a summer book-reading program on the language and early literacy outcomes of toddlers from high risk environments

The current study examined the impact of an early summer literacy program and the mediating effects of the home literacy environment on the language and literacy outcomes of a group of children at-risk for long-term developmental and academic delays. Participating children (n=54) were exposed to an intensive book-reading intervention each summer (June through mid August) over a 3-year period. The current study implemented an ex post facto, quasi-experimental design. This nonequivalent group design involved a pretest and posttest over three time points for a non-randomized treatment group and a matched non-treatment comparison group. Results indicated that literacy scores did improve for the children over the 3-year period; however, language scores did not experience the same rate of change over time. Receptive language was significantly impacted by attendance, and race/ethnicity. Expressive language was impacted significantly by gestational age and attendance. Results also indicated that language outcomes for young children who are exposed to a literacy program were higher than those who did not participate; however, only receptive language yielded significance at the p<.05 level. These study results also found that activities in the home that support literacy and learning do indeed impact language and literacy outcomes for these children, specifically, the age at which a child is read to, the number of books in the home, a child’s enjoyment of reading, and whether a child looks at books on his or her own impact language scores. This study concluded that at-risk young children do benefit from center-based literacy intervention. This literacy experience, however, is also driven by the children's home environment, their attendance to the program, whether they were premature or not and the type of caregiver.