共查询到20条相似文献，搜索用时 15 毫秒
1.
J. C. Defries Jim Stevenson Jacquelyn J. Gillis Sally J. Wadsworth 《Reading and writing》1991,3(3-4):271-283
The basic multiple regression model for the analysis of selected twin data (DeFries and Fulker 1985, 1988) was fitted to spelling data from 100 pairs of MZ twins and 71 pairs of same-sex DZ twins tested in the Colorado Reading Project (DeFries, Olson, Pennington and Smith 1991), and to data from 12 pairs of MZ twins and 15 pairs of same-sex DZ twins tested in the London twin study of reading disability (Stevenson, Graham, Fredman and McLoughlin 1984, 1987). Estimates of h
g
2
obtained from analyses of these data suggest that about 60% of the deficit of probands is due to heritable influences in both samples. When a regression model was fitted separately to data from males and females in the combined Colorado and London samples, resulting estimates of h
g
2
were 0.66±0.18 and 0.56±0.19, respectively, a nonsignificant difference. Collaborative analyses of data from additional twin studies of reading disability would facilitate more rigorous tests of hypotheses of differential genetic etiology as a function of group membership. 相似文献
2.
In order to assess the etiology of reading disability as a function of mathematics performance, data from 168 monozygotic (MZ) and 127 same-sex dizygotic (DZ) twin pairs in which at least one member of each pair was reading-disabled were subjected to quantitative genetic analyses. MZ and DZ concordance rates for reading disability were computed for different levels of mathematics performance, and reading performance data were fitted to an extension of the basic multiple regression model for the analysis of selected twin data. Results of these analyses suggest that genetic factors may be especially salient as a cause of reading disability in children with borderline deficits in mathematics performance: thus, mathematics performance may be a valid dimension for diagnosing subtypes of reading disability. 相似文献
3.
Astrom RL Wadsworth SJ Olson RK Willcutt EG Defries JC 《Learning and individual differences》2012,22(3):365-369
Reading performance data from 254 pairs of identical (MZ) and 420 pairs of fraternal (DZ) twins, 8.0 to 20.0 years of age, were subjected to multiple regression analyses. An extension of the DeFries-Fulker (DF) analysis (DeFries & Fulker, 1985, 1988) that facilitated inclusion of data from 303 of their nontwin siblings was employed. In addition to providing estimates of heritability, this analysis yields a test of the difference between shared environmental influences for twins versus siblings (Astrom et al., 2011). Results suggest that proband reading deficits are due substantially to genetic factors (.67 ± .07, p < .001), and that shared environmental influences are significantly higher for members of twin pairs than for those of twins and their nontwin siblings (viz., .25 versus .17, p = .02). 相似文献
4.
Jim Stevenson 《Reading and writing》1992,4(4):307-326
The issue of sex differences in reading disability has been of recent interest in relation to sex ratios in families with reading disabled children and to possible sex biases in referred populations. Data from a study of 570 twins are used to develop alternative definitions of reading disability that vary in the manner to which sex effects are taken into account. These definitions include discrepancies between reading quotients and IQ, the use of the regression of reading onto IQ and chronological age/reading age differences. In each case the reading and spelling disability was defined either separately for the sexes or based upon the data for the sexes combined and with and without an IQ>90 exclusion criterion. The consequences of using the alternative definitions for prevalence, sex ratio and heritability are examined. The results demonstrate that the characteristics of reading disabled children vary with the way disability is defined. The excess of males seems to be a robust finding. Definitions that take into account differences in mean score for males and females reduce but do not eradicate the sex ratio. From the genetic analysis, there is no support for the suggestion that the genetic effect on reading is greater for females than males. It is concluded that the use of regression based procedures for identifying reading disability is desirable but that at present there is insufficient evidence to justify the adoption of separate regression procedures for the two sexes. 相似文献
5.
B F Pennington J W Gilger R K Olson J C DeFries 《Journal of learning disabilities》1992,25(9):562-573
Recent research has raised the question of whether age- and IQ-discrepancy forms of reading disability (RD) are distinguishable in terms of either their underlying linguistic deficit or their response to treatment, thus threatening the external validity of the traditional distinction between specific reading retardation and reading backwardness. The present study pursued the external validity of this distinction in three domains: (a) genetic etiology, (b) sex ratio and clinical correlates, and (c) neuropsychological profiles. Each of these domains was explored in the RD (n = 640) and control (n = 436) twins participating in the Colorado Reading Project (514 males, 562 females, with an overall mean age of 12.42 years). Little evidence for external validity was found in terms of the clinical correlates of attention deficit-hyperactivity disorder (ADHD), immune disorders, or handedness. Most importantly, there was no evidence of differential genetic etiology of the two phenotypes in this sample, in that deficits in both phenotypes were similarly heritable (h2g = .40 and .46 for age and IQ phenotypes, respectively) and the genetic correlation between them was high (rG = .88 to .96). However, the genetic and neuropsychological profile analyses did suggest that age- and IQ-discrepancy definitions of RD may relate differentially to component reading processes, such as phonological awareness and orthographic coding. 相似文献
6.
Boada Richard Willcutt Erik G. Tunick Rachel A. Chhabildas Nomita A. Olson Richard K. DeFries John C. Pennington Bruce F. 《Reading and writing》2002,15(7-8):683-707
The present study examined the etiology of highreading ability in an overall sample of 350twin pairs in which at least one member of 100pairs (54 MZ, 46 DZ) had a reading compositescore one standard deviation above the sample mean. These highreaders also had significantly higher scoresthan the rest of the sample on Full Scale,Verbal and Performance IQ scores, as well as onmeasures of phoneme awareness, orthographiccoding, phonological decoding, and verbalshort-term memory. The MZ proband-wiseconcordance rate for high group membership wassignificantly higher than the DZ proband-wiseconcordance rate and further behavioralgenetic analyses corroborated that high readingability is partly due to genetic influence(h2
g = 0.55 ± 0.22). Bivariatemultiple regression analyses demonstrated thathigh phonological awareness, orthographiccoding, phonological decoding, and short-termverbal memory skills all share significantcommon genetic influence with high readingability. These results suggest that readingability and its cognitive correlates are on acontinuous distribution, with both extremes ofthe distribution being similarly heritable. They also support the hypothesis that the samecognitive processes that are associated withdyslexia are important for the development ofhigh reading ability. 相似文献
7.
Previous twin studies of reading disability employed a comparison of concordance rates in identical and fraternal twin pairs
as a test for genetic etiology. Recently, a statistically more powerful multiple regression analysis of twin data has been
formulated to assess the importance of genetic factors in the development of reading difficulties. Application of this analysis
to twin data from the Colorado Reading Project yields definitive evidence for a genetic etiology. Results from this study
suggest that approximately 40 percent of the deficit observed in the disabled readers is due to genetic factors, 35 percent
is due to environmental influences shared by members of twin pairs, and about 25 percent is the result of environmental factors
unique to the individual and/or error variance.
This work was supported in part by a program project grant from the NICHD (HD-11681). 相似文献
8.
In order to test the hypothesis that genetic influences are moreimportant as a cause of reading disability in girls than in boys,composite reading performance data from identical and fraternal twinpairs were analyzed using both concordance and multiple regressionmethods. The sample included 206 identical (99 male, 107 female), 159same-sex fraternal (90 male, 69 female), and 117 opposite-sex fraternaltwin pairs, in which at least one member of each pair had readingdifficulties. Although the difference between the concordance rates forreading disabilities in female identical and same-sex fraternal twinpairs was somewhat greater (65% for identical twins vs.32% for fraternal twins) than the difference in concordance ratesfor boys (68% vs. 39%), loglinear analysis of thesecategorical data revealed that the interaction between sex, zygosity,and concordance was not significant (p > 0.70). Moreover,the heritability of reading disability(h
2
g) estimated from regression analysisof the reading performance data in males was nearly identical to that infemales (h
2
g = 0.58 and 0.59,respectively; p > 0.90). Thus, results of this studyprovide little or no evidence for the hypothesis of greater geneticinfluence on reading difficulties in girls than in boys. 相似文献
9.
P. G. Aaron 《Annals of dyslexia》1987,37(1):109-125
A controversy whether developmental dyslexia is qualitatively different from other forms of reading disability has existed
among reading specialists for many years. In the present study, the hypothesis that the etiology of dyslexia is different
from that of other forms of reading disability because of differences in the components that malfunction was tested. A number
of studies have shown that the two components that contribute to a large proportion of variance in reading are decoding and
comprehension. It is, therefore, possible that a breakdown of different components could lead to different forms of disabilities.
College students who were poor readers were assigned to two groups on the basis of their IQ. Conforming to the traditional
criterion of dyslexia, those who had an IQ of 95 and above were considered as dyslexic. Those who had an IQ of 85 or below
were placed in the Nonspecific Reading-Disabled group. These two groups of poor readers and a group of normal readers were
administered a large number of reading-related tests. It was found that the two reading-disabled groups differed from each
other in six of the seven areas assessed. There was very little overlap of scores between the two groups in these areas. The
results were interpreted to suggest that poor decoding skill is the etiology of developmental dyslexia and that it differs
from other forms of reading disability which are caused by generalized cognitive deficits. 相似文献
10.
Erik G. Willcutt Rebecca S. Betjemann Sally J. Wadsworth Stefan Samuelsson Robin Corley John C. DeFries Brian Byrne Bruce F. Pennington Richard K. Olson 《Reading and writing》2007,20(1-2):103-125
Numerous studies have examined the etiology of the association between reading difficulties and attention-deficit hyperactivity
disorder (ADHD) in school-age children, but little is known about the relation between prereading skills and ADHD behaviors
prior to the beginning of formal reading instruction. A population-based sample of 809 pairs of preschool twins completed
an extensive battery of prereading measures, and the parent of each twin completed an ADHD rating scale. Phenotypic analyses
revealed small but significant correlations between DSM-IV inattention ratings and six prereading composite measures, whereas
hyperactivity–impulsivity symptoms were not independently associated with any of the prereading scores. Multivariate twin
analyses indicated that virtually all of the phenotypic correlation between inattention and prereading performance is attributable
to common genetic influences, consistent with results obtained in studies of older twins. Although additional research is
needed to test alternative causal models in children younger than five years old, these results are most consistent with the
hypothesis that reading difficulties and inattention symptoms are attributable to common genetic influences. 相似文献
11.
J M Fletcher K A Espy D J Francis K C Davidson B P Rourke S E Shaywitz 《Journal of learning disabilities》1989,22(6):334-8, 355
This study addressed the issue of specificity in reading disability by comparing two approaches to defining and selecting children with reading disabilities. One approach defined reading disability according to cutoff scores representing appropriate levels of intelligence and reading deficiency, whereas the other approach adjusted these scores for their intercorrelation through regression procedures. Results revealed clear differences in which children were identified as reading disabled according to the two definitions. However, differences in neuropsychological performance between children whose reading scores were discrepant or not discrepant with IQ were small and nonspecific for both definitions. The results of this study show that children identified as reading disabled vary according to the definition employed; at this point, there is little evidence suggesting any specificity of reading disability according to definition. 相似文献
12.
Susan Dickerson Mayes Daniel A. Waschbusch Susan L. Calhoun Richard E. Mattison 《Exceptionality》2020,28(1):60-75
ABSTRACTLittle is known about the characteristics of academic overachievers, children whose achievement significantly exceeds IQ. Correlates of overachievement (achievement test scores ≥ 1 SD above IQ), nondiscrepant achievement, and learning disability (LD; achievement ≥ 1 SD below IQ) were analyzed in 1,543 children (739 ADHD, 285 autism, and 519 general population), 6–16 years of age. Significant correlates of the reading and math achievement groups were diagnosis (autism greatest overachievement, ADHD greatest LD), IQ (lowest in overachievers and highest in LD), and Working Memory scores relative to the child’s IQ (close to or exceeding IQ in overachievers and lower than IQ in LD). Demographics (age, sex, race, and parent occupation) and parent and teacher ratings of psychopathology (e.g., behavior problems, anxiety, and depression) and personality characteristics (e.g., motivation and self-confidence) did not contribute significantly more to predicting overachievement and LD beyond that explained by IQ, diagnosis, and working memory. These findings suggest an underlying neurobiological etiology for both overachievement and LD. 相似文献
13.
Measures of early family adversity, pre-school-age IQ, school-age IQ, and reading ability were obtained from 779 Dunedin children. The data were used to examine the role of reading ability in the relationship between intellectual performance and teacher-reported behavior problems. Results of regression analyses showed that family adversity and pre-school-age IQ predicted problem behavior during the first year at school. However, reading scores accounted for a larger proportion of the variance in the later behavior problem scores than did school-age IQ scores, and when reading ability was entered in the regression equation before IQ, then reading but not IQ significantly predicted change in problem behavior during the primary school years. The results indicated that the association between IQ scores and problem behavior was mediated by reading ability and that a measure of school-age IQ has limited usefulness for models of primary school-age problem behavior. 相似文献
14.
In order to assess familial resemblance for measures of reading performance, data from 314 pairs of twins in which at least one member of each pair is reading-disabled [142 monozygotic (MZ) and 172 dizygotic (DZ) twin pairs], 273 matched control pairs (131 MZ and 142 DZ pairs), and their parents were subjected to both correlation and regression analyses. Results indicate that parent-offspring resemblance in families of reading-disabled probands does not differ substantially from that in families of controls. In general, the correlations and regressions for MZ twin pairs are greater than those for DZ twins; thus, individual differences in reading performance are due at least in part to heritable influences. As expected, regression coefficients are consistently larger than correlation coefficients for both parent-offspring and proband-cotwin comparisons in the reading-disabled sample, illustrating that regression analyses are more appropriate than correlations for assessing familial resemblance in selected samples. 相似文献
15.
The purpose of the present study was to explore the relative roles of IQ and cognitive processes in reading performance. A sample of 443 Spanish children (264 male, 179 female) ranging in age from 7 to 13 years were classified into four groups according to IQ scores (<80, 80–90, 90–110, >110) and reading disabled (RD) and normally achieving readers (NR) were compared. The findings indicate that IQ scores were not related to the differences between children with RD and NR. We found that reading‐related cognitive deficits do differentiate between RD and NR children. Therefore, IQ scores do not make a significant contribution to our understanding of reading disability. 相似文献
16.
Previous twin studies have provided evidence for genetic influences on reading disability (RD) or normal reading ability. The existence of subtypes of RD — each with its characteristic cognitive profile — has been suggested. Whether the etiology of the particular subtypes is genetic is uncertain. The present study examined within-pair comparisons of cognitive profiles (with respect to composites of general reading, symbol processing speed and sequential memory) in RD and control twins. Twin profile analysis were applied to these cognitive composites on 120 pairs of RD and control twins. Results showed a greater monozygotic (MZ) than dizygotic (DZ) resemblance in profiles indicating that individual differences in the patterning of cognitive abilities related to reading are genetically influenced. 相似文献
17.
The present study investigated the hypothesis that the higher prevalence of reading disability (RD) often observed among boys is partly an artifact of gender bias in the prediction of reading from IQ. The relevant regression statistics derived from a sample of more than 900 children revealed a statistically significant intercept bias. Predicted reading scores for boys were systematically overestimated, thereby inflating IQ-reading discrepancies; the converse was found for girls. When defined separately for girls and boys, severe underachievement in reading was found to be equally prevalent in both genders and, furthermore, was associated with qualitatively and quantitatively similar patterns of deficits. Because the bias arose from general differences between boys and girls in reading score distributions (a lower mean and greater variance for boys) rather than from differences in IQ scores, gender bias poses a potential threat not only to traditional IQ-discrepancy definitions but also to post-discrepancy definitions that are based solely on reading score cutoffs. Future classification criteria for RD need to take heed of the possibility that when the distributions of reading scores for boys and girls are not identical, performance cutoffs designating low achievement that are based on data pooled from both genders are likely to result in the overidentification of boys with RD and the underidentification of girls with RD. 相似文献
18.
Bonafina MA Newcorn JH McKay KE Koda VH Halperin JM 《Journal of learning disabilities》2000,33(3):297-307
Data suggest that children with reading disability (RD) and non-RD children with attention-deficit/hyperactivity disorder (ADHD) may comprise distinct subgroups. Research has been hampered by variance in definitional criteria, which results in the study of different subgroups of children. Using cluster analysis, this study empirically divided children with ADHD (N = 54), based on their Full Scale IQ (FSIQ) and reading ability. Four distinct subgroups emerged in which cognitive, behavioral, and neurochemical function was compared. Cluster 1 was of average FSIQ and reading scores; Cluster 2 was of average FSIQ but showed impairment in reading; Cluster 3 had high FSIQ and reading scores; and Cluster 4 had low scores in both domains. The groups had different patterns of cognitive, behavioral, and neurochemical function, as determined by discrepancies in Verbal-Performance IQ, academic achievement scores, parent aggression ratings, and a measure of noradrenergic function. These distinctions are discussed with regard to etiology, treatment, and long-term outcome. 相似文献
19.
In order to assess the validity of school history information as a diagnostic criterion for reading disability, reading performance data from 304 children with a positive history for reading problems were compared to those from 319 children with a negative school history. These children are members of twin pairs who are participants in the Colorado Reading Project (DeFries 1985). A multivariate analysis of variance of Reading Recognition, Reading Comprehension, and Spelling subtest scores from the Peabody Individual Achievement Test (Dunn and Markwardt 1970) yielded a highly significant (p <0.001) difference between groups for both the multivariate and univariate comparisons. The difference between the unweighted mean scores of the school-history positive and negative groups for Reading Recognition was 2.1 standard deviations. Moreover, when discriminant weights estimated from an independent sample of 140 reading-disabled and 140 control nontwin children were used to reclassify the sample of twins, 75% of those with a positive history for reading problems were classified as being reading disabled and 95% of those with a negative history were classified as unaffected. Thus, results of this study establish the validity of school history information and suggest that such information may have considerable utility for ascertaining samples of reading-disabled children. 相似文献
20.
J M Fletcher D J Francis B P Rourke S E Shaywitz B A Shaywitz 《Journal of learning disabilities》1992,25(9):555-61, 573
This study addressed the validity of distinguishing children with reading disabilities according to the presence or absence of discrepancies between intelligence test scores and academic achievement. Three definitions of reading disability were used to provide criteria for five groups of children who (a) met a discrepancy-based definition uncorrected for the correlation of IQ and achievement; (b) met a discrepancy-based definition correcting for the correlation of IQ and achievement; (c) met a low achievement definition with no IQ discrepancy; (d) met criteria a and b; and (e) met none of the criteria and had no reading disability. Comparison of these five groups on a set of 10 neuropsychological tests corrected for correlations with IQ showed that group differences were small and accounted for little of the variability among groups. These results question the validity of segregating children with reading deficiencies according to discrepancies with IQ scores. 相似文献