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1.
In order to compare the pattern of gender differences for cognitive measures in opposite-sex twin pairs to that in independent samples of twins from same-sex pairs, psychometric test data were obtained from four research-identified samples of children: (1) 96 pairs of opposite-sex fraternal twins in which at least one member of each pair is reading disabled; (2) 62 pairs of opposite-sex fraternal twins with no history of reading problems; (3) 167 males and 155 females from same-sex identical and same-sex fraternal twin pairs in which at least one member of each pair is reading disabled; and (4) a comparison sample of 126 males and 132 females from same-sex twin pairs with no history of reading problems. Results of multivariate analyses indicate that gender differences for cognitive measures are similar in twin pairs with and without reading disabilities. Moreover, a highly similar pattern of gender differences occurs for opposite-sex twin pairs who shared both prenatal and early postnatal influences and for independent samples of children from different families.  相似文献   

2.
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   

3.
Extensive psychometric test data were obtained from two independent samples of reading-disabled and control children: 70 probands and 75 controls tested on two occasions over an average interval of 4.2 years, and 35 probands and 22 controls tested on three occasions over an average interval of 8.6 years. When composite measures of reading performance and symbol-processing speed were subjected to mixed-model multivariate analyses of variance, significant effects due to group (reading-disabled versus control) and time (i.e., test session) were obtained in both samples, and a significant group-by-time interaction was obtained for the sample tested on three occasions. In general, rates of change in reading performance are highly similar for reading-disabled and control children. However, with regard to symbol-processing speed, differences between the two groups increase as a function of age. Although no evidence was obtained for differential longitudinal stability of either composite measure in reading-disabled and control children, results of a multiple regression analysis suggest that reading deficits during middle childhood are highly predictive of later reading problems, even into early adulthood. This work was supported in part by a program project grant from the NICHD (HD-11681). The invaluable contributions of staff members of the many Colorado school districts and of the families who participated in the study are gratefully acknowledged.  相似文献   

4.
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   

5.
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   

6.
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   

7.
Differential genetic etiology of reading disability as a function of IQ   总被引：5，自引：0，他引：5  
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.  相似文献   

8.
To test the hypothesis that the etiology of reading difficulties may differ for males and females in more severely impaired samples, reading performance data from monozygotic (MZ), same-sex dizygotic (DZss), and opposite-sex dizygotic (DZos) twin pairs were analyzed using a model-fitting implementation of the DeFries-Fulker (DF) model (Purcell & Sham, 2003, Behavior genetics, 33, 271–278). Five non-independent samples were selected using cut-offs of −1 (N = 737 pairs), −1.5 (N = 654), −2 (N = 468), −2.5 (N = 335), and −3 (N = 198) standard deviations (s) below the mean composite reading score of control twins. Male/female gender ratios for children with reading difficulties were significantly higher than 1.0 for all five samples and increased as a function of severity (viz., 1.15, 1.17, 1.40, 1.61, and 1.88, respectively). When the DF model was fit to the data, estimates of heritability (h g2) and shared environmental influences (c g2) were not significantly different for males and females in any of the groups. Consequently, the most parsimonious model that provided a good fit to the data at all five levels of severity equated the heritabilities and shared environmental influences for males and females, and fixed the DZos coefficient of genetic relatedness at 0.5. Thus, these results provide no evidence for a differential etiology of reading difficulties as a function of gender in more severely impaired samples, and suggest that the same genetic and environmental influences contribute to reading difficulties in males and females, irrespective of severity.  相似文献   

9.
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   

10.
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   

11.
Factor scores from Bayley's Infant Behavior Record, obtained from about 300-400 infant twins at 6, 12, 18, and 24 months, were selected to represent 3 aspects of infant behavior: task orientation, test affect-extraversion, and activity. Age-to-age correlations for the scores yielded a simplex pattern of low to moderate order. Further age-to-age analyses by twin pairs generally showed that the identical twins, as compared with same-sex fraternal twins, generated more within-pair similarities for profiles of the factor scores across 2 overlapping age ranges: 6-18 months, and 12-24 months. Overall, the findings indicated that there is reordering of individual differences for aspects of infant behavior from one age to the next, but the sequence of reordering is somewhat structured in accord with genotypic similarity. The longitudinal findings are also discussed within the context of change and continuity of the individuality of infant temperament.  相似文献   

12.
Measures of word recognition (REC) and two component skills, phonological coding (PHON) and orthographic coding (ORTH), were subjected to multivariate behavioral genetic analysis. Data were obtained from a sample of identical and fraternal twin pairs wherein at least one member of each pair was reading disabled (RD), and from a sample of twins wherein both members of each pair read in the normal range. Confirmatory factor analysis was used to fit the genetic, common environmental, and specific environmental covariance components for REC, PHON, and ORTH within the RD and normal simples. The resulting heritability estimates for REC, PHON, and ORTH were 0.59, 0.41, and 0.05 in the RD sample, and 0.35, 0.52, and 0.20 in the normal sample. After dropping the nonsignificant common environment parameters from the models, the genetic correlations between REC and PHON and between REC and ORTH were respectively 0.81 and 0.45 in the RD sample, and 0.68 and 0.45 in the normal sample. Differences between the genetic correlations were significant in the RD sample (p<0.005), marginally significant in the normal sample (p<0.10), and highly significant in the combined sample (p<0.001), indicating that genetic influences on individual differences in REC are more strongly related to genetic variance in PHON than in ORTH. These results are consistent with previous demonstrations of substantial genetic covariance between the disabled group's deficits in REC and PHON, but not between REC and ORTH (Olson et al., 1989; Olson and Rack, 1990).  相似文献   

13.
Reviews involving the Wechsler Scales for children suggest that Full Scale IQ scores on the Wechsler Intelligence Scale for Children, Third Edition, average 5 to 6 points lower than scores on the second edition of the scale [WISC‐R, Wechsler, D. (1974). Zimmerman & Woo‐Sam, 1997], with the differences distributed disproportionately over subtests, i.e., with larger discrepancies found within the Performance Scale (Wechsler, 1991). Changes on the revised subtests of the WISC‐III Performance Scale may place children with ADHD at a disadvantage compared to their performance on analogous WISC‐R subtests. We examined IQ test performance in 122 unmedicated children with ADHD (61 given the WISC‐R, 61 given the WISC‐III), and 46 children from a healthy, comparison group (23 given the WISC‐R, 23 given the WISC‐III). The ADHD and comparison group samples were matched for sex and for Verbal IQ between WISC‐R and WISC‐III. Children with ADHD had significantly lower Performance IQ on WISC‐III compared to the WISC‐R, with the Picture Arrangement subtest showing the most significant difference. In contrast, there were no significant differences between the WISC‐R and WISC‐III cohorts on Performance IQ or any Performance subtests among the comparison group. These findings highlight the importance of examining the comparability of ability test revisions among clinical and non‐clinical populations, and will be especially salient when the WISC‐III is revised. © 2003 Wiley Periodicals, Inc. Psychol Schs 40: 331–340, 2003.  相似文献   

14.
Gender differences in level and pattern of cognitive abilities were examined in 28 LD college-able females (CA 18–25) as compared to 21 LD college-able males (CA 18–25). Both groups were in the average IQ range as measured by the Wechsler Adult Intelligence Scale, with LD males significantly higher on the Full Scale IQ and three out of the four subtests, Picture Completion, Block Design, and Information. The LD females performed significantly better on the Digit Symbol subtest. The hierarchies of subtest performance and Bannatyne and ACID category scores were compared. LD females have strengths in visual-motor abilities and verbal conceptualization, while the LD males’ highest abilities were nonverbal visual-spatial confirming earlier studies on younger LD individuals and non-LD males and females. Performance on the Digit Symbol subtest was the next to the lowest for the males, the highest for females. However, for both groups, short-term and long-term memory for digits and factual knowledge and mental arithmetic problem solving were relative weaknesses. Results indicate different patterns of cognitive abilities in LD females and males which have implications for identification, service, and prognosis for the learning disabled, especially females.  相似文献   

15.
The current study examined the relationship in Spanish (i.e., a transparent orthography) between different levels of phonological awareness and reading disabilities. In addition, the strategies used by the children when they resolved phoneme segmentation and reversal tasks were analyzed. A sample of 133 subjects were selected and organized in three different groups: (1) A group of 45 reading-disabled children, (2) A comparison group of 44 normal readers matched in age with the reading disabled, and (3) A reading level match group of 44 younger normal readers at the same reading level as the reading disabled. Three phonological awareness tasks were used to measure levels of intrasyllabic and phonemic awareness. The reading disabled group was equivalent to the younger reading level-matched control group in the odd-word-out task. However, there were differences in the phonemic tasks (e.g., phoneme segmentation and reversal) because the reading disabled group performed more poorly than the younger children. Overall, the children matched in age with the reading disabled group were superior in all phonological awareness tasks. There were differences between the groups when the strategies used by the children were analyzed.  相似文献   

16.
Data from 104 reading-disabled subjects tested on two occasions over an average interval of nearly five years were used to test hypotheses of differential prognosis for reading performance and symbol-processing speed as a function of gender, socioeconomic status, general intelligence, and initial severity. With respect to reading performance, significant main effects due to intelligence and severity were found. Moreover, the interaction between initial severity and test occasion was significant for reading performance due to a greater rate of improvement for the more severely disabled subjects. No evidence was obtained, however, for differential developmental rates as a unction of gender, socioeconomic status, or intelligence for this measure. With regard to symbol-processing speed, significant main effects were found due to gender, intelligence, and severity, whereas developmental rates were found to differ as a function of gender and socioeconomic status.  相似文献   

17.
D C Rowe 《Child development》1983,54(2):416-423
Biometrical genetic analysis was applied to sibling and twin kinship data on 2 dimensions of perceived home environment. Correlations on 1 dimension, Restrictiveness-Permissiveness, were equal and significant for all kinships: MZ twins, DZ twins, same-sex siblings, and opposite-sex siblings significant for all 4 kinships: MZ twins, DZ twins, same-sex siblings, and opposite-sex siblings (r greater than .40). An E2-E1 biometrical model fitted Restrictiveness-Permissiveness, implying that treatments common to siblings create agreement about perceived environment. As intrapair differences were the same for all 4 kinships under this model, the equal environments assumption of the twin method was supported. In contrast, the Acceptance-Rejection dimension fitted a G-E1 model that makes the assumption that sibling similarity is the result of genetic factors and postulates an absence of shared environmental influences. This finding suggests that this aspect of home environment may depend as much on the child's inherited traits as on actual treatments and is in accord with the genetic analysis of individual traits in that developmentally effective environmental factors do not appear to be common to siblings.  相似文献   

18.
Findings from an analysis of the reading performances of three reading-disabled children provide a tentative answer to the controversial issue whether reading-disabled children have a language comprehension deficit or not. Of the three reading-disabled children studied, two were poor in language comprehension but had much better word-reading skill. The third disabled reader had superior listening comprehension but was poor in word-reading skill. The two good word-readers appear to use two different strategies, viz., grapheme—sound association and whole word-pronunciation asssociation to pronounce the written word. It is concluded that pronunciation and comprehension skills are two dissociable components of the reading process and that they follow separate courses of development. Case studies presented in this paper suggest that these two components can be affected independent of each other resulting in different types of reading disabilities. It is concluded that answer to the question whether poor readers are also deficient in language comprehension depends on the type of disabled readers investigated even though educational experience and severity of the reading problem can act as confounding factors.
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19.
The present study focused on gender differences in the tendency to omit items and to guess in multiple-choice tests. It was hypothesized that males would show greater guessing tendencies than females and that the use of formula scoring rather than the use of number of correct answers would result in a relative advantage for females. Two samples were examined: ninth graders and applicants to Israeli universities. The teenagers took a battery of five or six aptitude tests used to place them in various high schools, and the adults took a battery of five tests designed to select candidates to the various faculties of the Israeli universities. The results revealed a clear male advantage in most subtests of both batteries. Four measures of item-omission tendencies were computed for each subtest, and a consistent pattern of greater omission rates among females was revealed by all measures in most subtests of the two batteries. This pattern was observed even in the few subtests that did not show male superiority and even when permissive instructions were used. Correcting the raw scores for guessing reduced the male advantage in all cases (and in the few subtests that showed female advantage the difference increased as a result of this correction), but this effect was small. It was concluded that although gender differences in guessing tendencies are robust they account for only a small fraction of the observed gender differences in multiple-choice tests. The results were discussed, focusing on practical implications.  相似文献   

20.
Word reading and math computation scores were predicted from Wechsler Abbreviated Scale of Intelligence Full Scale IQ, 10 neuropsychological tests, and parent attention deficit hyperactivity disorder (ADHD) ratings in 214 general population elementary school children. IQ was the best single predictor of achievement. In addition, Digit Span contributed significantly to reading prediction, and the Developmental Test of Visual-Motor Integration (VMI) and Coding contributed to math prediction. The remaining neuropsychological test scores did not significantly improve achievement prediction. Exploratory factor analysis yielded a general ability factor (comprising the four IQ subtests, Digit Span, VMI, reading, and math), five factors made up solely of subtests from single measures (Wisconsin Card Sorting Test, Stroop Color and Word Test, Gordon Diagnostic System, California Verbal Learning Test, and ADHD ratings), a factor consisting of Grooved Pegboard Test and Coding, and a factor consisting of Symbol Search and Animal Naming Test.  相似文献   

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