Multiple regression analysis of sib-pair data on reading to detect quantitative trait loci

A simple extension of the DeFries and Fulker multiple regression model for twin analysis is applied to the problem of detecting linkage in a quantitative trait. The method, employing sib pairs, is based on that of Haseman and Elston. Reading data from 19 extended pedigrees were analyzed employing RLFPs as markers on chromosome 15 and using the widely available statistical applications software package, SAS. A number of possible linkages were detected, indicating that this approach is both powerful and effective, especially in the case of selected samples. Detecting genotype-environment interaction and the issue of power are briefly discussed. The programs used are available upon request.     

Pedagogies of critical race theory: Experimentations with white preservice teachers

We have taken to heart the call of critical race theorists and critical Whiteness scholars to open up a White discourse on White racism. As White, female, teacher educators, we endeavored to openly address Whiteness and White racism with our White students to help them become more aware of the advantages and biases inherent in their positionality as White teachers. As we did this, we were critically aware of both the negative and positive possible outcomes of our endeavors. Throughout our work with our students and our subsequent reflections on the results, we were able to establish ways of speaking about Whiteness that moved our students, and ourselves, to a more critical, more empowered understanding of race and Whiteness.     

Reliability and validity of the adult reading history questionnaire

The reliability and validity of a revised version of Finucci's (1982) Reading History Questionnaire was examined in two adult samples. One sample included 84 adults from an ongoing study of familial dyslexia, and a second sample was composed of parents of 107 children from a longitudinal study of reading development. Internal consistency was demonstrated by Cronbach's alphas of .94 and .92 in the two samples. Test-retest reliability was demonstrated by significant correlations (.87 and .84 in the two samples) over several years between an earlier and revised form of the questionnaire. Validity was demonstrated via (a) correlations between the questionnaire score and reading measures (rs = .57-.70), (b) the results of a discriminant function analysis that used questionnaire scores to predict reading disability diagnosis, and (c) the finding that the questionnaire had substantial incremental validity in predicting reading skill in a hierarchical regression analysis that first entered IQ and SES. These results indicated that the questionnaire is both reliable and valid.     

Using genetics to understand dyslexia

This paper reviews what is currently known about the genetics of dyslexia and shows how genetic studies can help clarify which symptoms are primary and which are secondary in dyslexia. On the genetic side, current evidence supports the view that dyslexia is familial, substantially heritable, and heterogeneous in its genetic mechanisms. At least some forms of familial dyslexia appear to be autosomal dominant, with linkage studies supporting both a major locus on chromosome 15 and genetic heterogeneity. On the symptom side, current evidence supports the view that the primary symptom in dyslexia is a deficit in the phonological coding of written language. This primary symptom likewise appears to be heritable. Recent evidence suggests that the heritable precursor to this written language deficit is a spoken language deficit in the skill of phoneme segmentation and awareness.     

Genetic and Environmental Etiologies of the Longitudinal Relations Between Prereading Skills and Reading

The present study explored the environmental and genetic etiologies of the longitudinal relations between prereading skills and reading and spelling. Twin pairs (n = 489) were assessed before kindergarten (M = 4.9 years), post‐first grade (M = 7.4 years), and post‐fourth grade (M = 10.4 years). Genetic influences on five prereading skills (print knowledge, rapid naming, phonological awareness, vocabulary, and verbal memory) were primarily responsible for relations with word reading and spelling. However, relations with post‐fourth‐grade reading comprehension were due to both genetic and shared environmental influences. Genetic and shared environmental influences that were common among the prereading variables covaried with reading and spelling, as did genetic influences unique to verbal memory (only post‐fourth‐grade comprehension), print knowledge, and rapid naming.     

Transitioning in higher education: an exploration of psychological and contextual factors affecting student satisfaction

In view of recent changes in the higher education sector, such as increased tuition fees, a greater focus has been placed on widening participation initiatives and monitoring student satisfaction. The aims of the current study were twofold: (1) to explore whether pre-entry programmes foster successful transition to higher education, and (2) to examine longitudinally the factors associated with course satisfaction. Eighty-eight first-year psychology students completed a questionnaire measuring academic self-efficacy, social identity and student satisfaction at the start (Time 1, November 2015) and end (Time 2, March 2016) of the academic year. Findings indicated that students who participated in a pre-entry programme reported higher academic self-efficacy and satisfaction compared to typical route students. Moreover, academic self-efficacy predicted student satisfaction at the start of the academic year, whereas in-group affect (a facet of social identity) predicted this at the end of the academic year. The current findings indicate that pre-entry programmes may have a positive impact on students’ sense of academic self-efficacy. On a more general level, the findings also suggest that academic self-efficacy and social identity may be key indicators of student satisfaction. This highlights the complexities of the concept of ‘student satisfaction’, and demonstrates the utility of examining multiple factors relating to student satisfaction across different time points.     

Differential genetic etiology of reading disability as a function of IQ

To test the hypothesis that the genetic etiology of reading disability differs as a function of IQ, composite reading performance data from 223 pairs of identical twins and 169 pairs of same-gender fraternal twins in which at least one member of each pair was classified with reading disability were subjected to multiple regression analysis (DeFries & Fulker, 1985, 1988). In the total sample, heritability of the group deficit in reading performance (h(g)2) was .58 (+/- .08). However, when the basic regression model was fitted separately to data from twin pairs with average Wechsler (1974, 1981) full scale IQ scores below 100 or 100 and above, resulting estimates of h(g)2 were .43 and .72, respectively, a significant difference (p < or = .03, one-tailed). The results of fitting extended regression models to reading performance and continuous IQ data provide evidence that the genetic etiology of reading disability differs as a linear function of IQ (p < or = .007, one-tailed). These results suggest that IQ is relevant for the diagnosis of reading disability and that environmental influences may be more salient as a cause of reading difficulties in children with lower IQ scores.     

Spelling errors and reading fluency in compensated adult dyslexics

Generally, a person who is diagnosed as dyslexic remains diagnosably dyslexic all his/her life. However, occasionally, an individual compensates for his/her difficulties in some way, and by adulthood is no longer diagnosably dyslexic. In what ways are these compensated dyslexics different from both dyslexics and nondyslexics? We compared IQ, achievement test, and spelling error scores in adult dyslexics, adult nondyslexics, and adult compensated dyslexics (N=25) in the two studies reported here. The second study differed from the first in that the subjects were matched for age, education, IQ, and SES. In both studies, compensateds were significantly different from nondyslexics on the WRAT Spelling subtest and Reading Quotient scores. In the second study the compensateds differed from the nondyslexics in total raw score and average reading speed on Gray Oral Reading Test. On the other hand, they were different from dyslexics on all reading and spelling variables in both studies, except for PIAT Reading Comprehension in Study 2. Finally, in Study 2, the compensateds were different from both dyslexics and nondyslexics in average reading speed. In conclusion, it appears that compensation does not result from differences in IQ, education, or SES, though it may be influenced to some extent by sex. Compensateds appear very similar to nondyslexics in their reading and spelling skills; however, there appears to be a difference in the automaticity with which they apply these skills.     

Neuropsychology of Early-treated Phenylketonuria: Specific Executive Function Deficits

This study explored the hypothesis that children with early-treated phenylketonuria (PKU) are selectively impaired on executive function measures, even when still on diet. The rationale for this hypothesis is that even mild elevations in phenylalanine (Phe) can lead to lower central levels of biogenic amines, including dopamine (DA). We hypothesize that this mild DA depletion causes subtle prefrontal dysfunction, which in turn affects executive functions such as set maintenance, planning, and organized search. 11 preschool early-treated PKU children (M age = 4.64) and a sample of age- and IQ-matched unaffected peers (n = 11) were evaluated on a battery of executive function (EF) measures. In addition, a "non-executive function" task, recognition memory, was administered to all subjects. Group comparisons demonstrated that PKU children were significantly impaired on an executive function composite score; there were no group differences, however, in recognition memory. These results supported the hypothesized specific deficit in executive function. Furthermore, within the PKU group the executive function composite score was significantly negatively correlated with concurrent phenylalanine levels, even after controlling for the correlation between IQ and executive function skills. This second finding provides support for the proposed biochemical mechanism underlying the specific cognitive deficits.