Gender differences in cognitive abilities of reading-disabled twins

Gender differences were assessed in three research-identified samples of children who were members of twin pairs: (1) 120 male and 124 female probands from same-sex identical and fraternal twin pairs in which at least one member of each pair is reading disabled; (2) a comparison sample of 148 males and 161 females from same-sex twin pairs with no history of reading problems; and (3) 34 pairs of opposite-sex fraternal twin pairs in which at least one member of each pair is reading disabled. Results of multivariate analyses of variance of psychometric test data from the two samples of same-sex twin pairs, in which the male and female subjects were reared in different homes, suggest that profiles of gender differences are similar in reading-disabled and control children. Moreover, this pattern of gender differences also tended to occur in opposite-sex twin pairs, who shared prenatal, as well as early postnatal, environmental influences. In general, reading-disabled males obtained higher average scores than affected females on Wechsler (1974, 1981) Verbal and Performance IQ, but lower scores on Reading Recognition and Spelling subtests of the Peabody Individual Achievement Test (Dunn and Markwardt 1970). With regard to the Wechsler subtests, reading-disabled males achieved higher average scores on Information, Picture Completion, Block Design, and Object Assembly, but lower scores on Coding. Although significant and relatively consistent gender differences in cognitive measures were found in three samples included in this study, these differences account for only a small portion of the observed variance. This work was supported in part by a program project grant from NICHD (HD-11681), and the report was prepared while J.J. Gillis was supported by NICHD training grant HD-07289.     

Individual differences in sign language abilities in deaf children

The study attempted to identify characteristics of individual differences in sign language abilities among deaf children. Connections between sign language skills and rapid serial naming, hand motor skills, and early fluency were investigated. The sample consisted of 85 Finnish deaf children. Their first language was sign language. Simple correlations and multiple linear-regression analysis demonstrated the effect of early language development and serial hand movements on sign language abilities. Other significant factors were serial fingertapping and serial naming. Heterogeneity in poor sign language users was noted. Although identifying learning disorders in deaf children is complicated, developmental difficulties can be discovered by appropriate measurements. The study confirmed the results of earlier research demonstrating that the features of deaf and hearing children's learning resemble each other. Disorders in signed and spoken languages may have similar bases despite their different modalities.     

Individual differences in cognitive synthesis: An M-capacity analysis

Individual differences in children's propensity to demonstrate cognitive synthesis were evaluated using an artificial reading task. Six-year-olds were asked to demonstrate the meaning of various sentences constructed of logographs, or whole-word symbols, which were arranged in either a meaningful (i.e., grammatical) or scrambled (i.e., ungrammatical) order. Some children demonstrated the sentences in a synthesized mode (expressing a single idea unit), while others used a nonsynthesized mode (expressing the meanings of individual logographs). Overall, synthesizers had a larger attentional reserve, or M-capacity, than nonsynthesizers. The two groups did not differ significantly in age, intellectual level, or reading achievement. As predicted by their larger M-capacity, synthesizers demonstrated from memory significantly more items from meaningful sentences than nonsynthesizers. However, when synthesizers attempted to integrate the scrambled sentences, the excessive operative schemes needed to reorganize the items reduced their recall performance to the level of nonsynthesizers.     

Gender differences in cognitive abilities of learning-disabled females and males

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.     

Individual differences in mathematical ability: genetic, cognitive and behavioural factors

Identifying individuals with mathematical difficulties (MD) is becoming increasingly important in our education system. However, recognising MD is only the first stage in the provision of special educational needs (SEN). Although planning the effective remedial support is vital, there is little consensus on the interventions that are appropriate. There are two main reasons for this: first, MD has a variety of manifestations which appear to change with age; and second, there are many potential causes for the difficulties individuals experience. This paper addresses these issues by reviewing research evidence from three 'domains' of psychological research (genetic, cognitive, behavioural), all of which appear to offer insights into potential influences on mathematical ability.     

Sources of age differences in speed of processing

3 experiments were conducted to study developmental change in the speed of cognitive processes. In Experiment 1, subjects ranging in age from 8 to 21 years were tested on a mental rotation task in which they judged whether pairs of letters presented at different orientations were identical or mirror images, and on a name retrieval task in which they judged if pairs of pictures were identical physically or had the same name. Increases with age in the speed of mental rotation and speed of name retrieval were both well described by exponential functions, and the rate of developmental change was comparable for the 2 tasks. Experiment 2 confirmed that age changes in rate of mental rotation are well described by an exponential function. Experiment 3 demonstrated, on a mental rotation task, a perfect correlation across conditions between children's mean response times and adults' mean response times for corresponding conditions. These results are interpreted as indicating that age differences in speed of processing are due, at least in part, to a central limiting mechanism that increases with age.     

Structural extensions of a hierarchical view on human cognitive abilities

During the 1990s, research within the Individual Differences Unit at the University of Sydney was oriented towards expanding knowledge of poorly understood domains of human cognition. Using the theory of fluid and crystallized intelligence (Gf/Gc) served as the overarching framework. This research has led to an improved understanding of the nature of complexity and the role of working memory in Gf. Another outcome has been the charting of factors underlying of mental speed, tactile/kinesthetic performance, and olfactory memory. Recently, there has been exploration of the “borderline area” between abilities and personality. Our work on self-confidence and self-monitoring of cognitive performance has demonstrated excellent measurement properties of scores based on confidence ratings. We have also established a clear separation of a broad self-confidence factor from traditional intelligence and personality factors. Our research in these borderline areas has also explored the status of emotional intelligence. Results from several studies raise questions regarding the measurement of this construct.     

Individual differences in infants' information processing: reliability, stability, and prediction

A group of 46 full-term and 54 high-risk preterm (less than 1,500 grams birthweight) infants were tested at 6, 7, and/or 8 months of age (corrected age for preterms) on a battery of problems assessing visual recognition memory and tactual-visual cross-modal transfer. At all 3 ages, scores obtained on aggregates of 6-11 problems in the battery significantly predicted 3-year Stanford-Binet IQ: correlations ranged from r = .37 to r = .63, and clustered between r = .50 and r = .60. When aggregates from 2 or 3 ages were used as predictors, multiple correlations were as high as R = .60 and R = .70. Cutoffs for predicting children at risk for mental retardation (IQ less than 70) or cognitive delay (IQ less than 85) showed reasonable sensitivity and specificity, although low scores were poor at detecting IQs less than 70. The internal consistency of composites, indexed by alpha coefficients, was unexpectedly low, primarily because the problems shared little variance. However, stability coefficients between assessments as much as 1 and 2 months apart were moderate in magnitude, ranging from r = .30 to r = .50. Considering the high degree of predictive validity, the stability figures appear to be better estimates of reliability for these measures than are indices of internal consistency. The relations reported here were similar for both full-terms and preterms.     

Gender differences in mental simulation during sentence and word processing

Text comprehension requires readers to mentally simulate the described situation by reactivating previously acquired sensory and motor information from (episodic) memory. Drawing upon research demonstrating gender differences, favouring girls, in tasks involving episodic memory retrieval, the present study explores whether gender differences exist in mental simulation in children (Grades 4 to 6). In Experiment 1, 99 children performed a sentence–picture verification task measuring mental simulation at sentence level. In Experiment 2, 97 children completed a lexical decision task in which imageability of words was manipulated to measure mental simulation at word level. Only for girls we found faster reaction times for matching versus mismatching sentence–picture pairs (Experiment 1) and high‐imageability versus low‐imageability words (Experiment 2). The results suggest that girls construct more coherent and vivid mental simulations than boys and rely more heavily on these representations. The results emphasize the importance of including gender into reading comprehension research. [Correction added on 13 June 2016, after first online publication: The affiliation of author “Björn B. de Koning” was previously wrong and has been corrected in this current version.]     

Gender differences in cognitive abilities of opposite-sex and same-sex twin pairs with reading disabilty

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.     

Individual differences in cognitive skills related to reading ability in the deaf

Deaf subjects who represented a wide range of reading abilities were tested on a number of factors including reliance on phonological recoding as well as several metacognitive abilities. The sample consisted of 19 high school students who were prelingually and profoundly deaf. Subjects were given a set of paper and pencil tests that included an assessment of phonological recoding ability as well as the measures designed by Baker (1984) to assess metacognitive skills in reading. Results indicated that deaf subjects demonstrated a significant degree of reliance on phonological recoding, but that individual differences in reliance on phonological recoding showed no relationship to reading skill (r = .02). Individual differences on the metacognition measures, however, showed a strong relationship to reading ability (r = .65, p less than .01). The implications for remedial instruction for deaf students are discussed.     

Individual differences in dynamic measures of verbal learning abilities in young twin pairs and their older siblings

We explored the genetic background of individual differences in dynamic measures of verbal learning ability in children, using a Dutch version of the Auditory Verbal Learning Test (AVLT). Nine-year-old twin pairs (N = 112 pairs) were recruited from the Netherlands Twin Register. When possible, an older sibling between 10 and 14 years old participated as well (N = 99). To assess verbal learning, non-linear curves were fitted for each child individually. Two parameters were estimated: Learning Speed (LS) and Forgetting Speed (FS). Larger twin correlations in monozygotic (MZ) than in dizygotic (DZ) and sibling pairs for LS and FS indicated the importance of genetic factors in explaining variation in these traits. The heritability estimate (percentage of variance explained by genetic factors) for LS was 43% for both twins and siblings. For FS heritability was estimated at 20% in twins and was slightly higher (30%) in their older siblings.     

Attention deficit disorder with and without hyperactivity: reaction time and speed of cognitive processing

This study addressed the issue as to whether children reliably diagnosed as attention deficit disordered with hyperactivity (ADD/H) and without hyperactivity (ADD/WO) differed significantly from each other and a clinic control (CC) population on speed and efficiency of cognitive processing. From an outpatient clinic population, 43 ADD/H and 22 ADD/WO children were examined. An analysis of mean reaction time and speeded classification task performance revealed significant group effects on both mean reaction time and on a measure of within-subject variability. ADD/H children performed significantly more slowly and variably than the CC children on several of the speeded classification tasks. However, the ADD/WO group was not distinguished on any measure. Thus, while children may be reliably diagnosed as ADD/H or ADD/WO using behavioral measures, it would appear that they cannot be distinguished on these neurocognitive tasks. Issues related to childhood psychopathology and the neuropsychological basis of ADD/H are discussed.     

Individual differences in achievement goals: A longitudinal study of cognitive, emotional, and achievement outcomes

Within achievement goal theory debate remains regarding the adaptiveness of certain combinations of goals. Assuming a multiple-goals perspective, we used cluster analysis to classify 1002 undergraduate students according to their mastery and performance-approach goals. Four clusters emerged, representing different goal combinations: high mastery/performance (i.e., multiple goals), dominant mastery, dominant performance, and low mastery/performance (i.e., low motivation). In a longitudinal analysis over one academic year, the clusters were compared on cognitive appraisals (expected achievement, perceived success), achievement-related emotions (enjoyment, boredom, anxiety), and objective measures of academic achievement (final grade in Introductory Psychology, GPA). The low-motivation cluster demonstrated the least adaptive profile across all outcomes. The multiple-goals, mastery, and performance clusters showed equivalent levels of achievement; however, students in the performance cluster were more psychologically and emotionally vulnerable than the multiple-goals and mastery clusters. Our discussion focuses on the immediate and potentially long-term implications of specific goal combinations for students and educators, with particular attention to understanding the cognitive and emotional vulnerabilities of students in the performance cluster which appear despite satisfactory achievement levels.     

Development of mental attention in gifted and mainstream children: the role of mental capacity, inhibition, and speed of processing

The study examined performance of 6- to 11-year-old children, from gifted and mainstream academic programs, on measures of mental-attentional capacity, cognitive inhibition, and speed of processing. In comparison with mainstream peers, gifted children scored higher on measures of mental-attentional capacity, responded more quickly on speeded tasks of varying complexity, and were better able to resist interference in tasks requiring effortful inhibition. There was no group difference on a task requiring automatic inhibition. Comparisons between older and younger children yielded similar results. Correlations between inhibition tasks suggest that inhibition is multidimensional in nature, and its application may be affected by task demands. Measures of efficiency of inhibition and speed of processing did not explain age or group differences on a complex intellective measure of mental-attentional capacity.     

Individual differences in RAN and reading: a response timing analysis

Thirty 8–11‐year‐old children were administered tests of rapid naming (RAN letters and digits) and reading‐related skills. Consistent with the hypothesis that RAN predicts reading because it assesses the ability to establish arbitrary mappings between visual symbols and verbal labels, RAN accounted for independent variance in exception word reading when phonological skills were controlled. Response timing analysis of different components of RAN digits and letters revealed that neither average item duration nor average pause duration were unique predictors of reading skill. However, the number of pauses on digit naming predicted unique variance in exception word reading. Moreover, better readers paused more strategically than poorer readers (e.g. more often at the ends of lines). We suggest that rapid automatised naming may in part reflect differences in strategic control that are a result of differences in reading practice and experience.     

Further evidence for a multifaceted model of mental speed: Factor structure and validity of computerized measures

The purpose of this study was to replicate the structure of mental speed and relations evidenced with fluid intelligence (Gf) found in a number of recent studies. Specifically, a battery of computerized tasks examined whether results with paper-and-pencil assessments held across different test media. Participants (N = 186) completed the battery, which incorporated 20 elementary cognitive tasks, 4 broad speediness (Gs) measures, and 5 Gf markers. Competing measurement models were tested. A higher-order model, with a general mental speed factor and 7 task-class specific factors fit the data well. Gs could not be distinguished from general mental speed. Besides the general mental speed factor, two task-class specific factors were moderately related to Gf. These findings strengthen the evidence for a multifacted structure of mental speed, and highlight the importance of specific speed task-classes in accounting for meaningful outcomes.     

Sex differences in learning abilities and disabilities

Boys more often than girls are affected by all the cognitive developmental disorders of childhood. Differences in the etiology of learning disabilities as well as general sex differences in learning styles in boys versus girls may explain the male preponderance in the prevalence of learning disabilities. The effects on learning of hormonal sex differences, maturation rate differences, and differences in frequency of perinatal brain injury will be discussed.     

Toward a cognitive schemata theory of self-instruction

An initial outline of a cognitive schemata theory of self-instruction is presented. Three levels of schemata are described briefly. Attention then is devoted to the cognitive organization and operation of these schemata in relation to procedural and declarative knowledge stores, and in relation to everchanging situational information. The primary objective is to provide an initial basis for conceptualizing the cognitive competence required for self-instruction.Requests for reprints should be directed to Jack Martin, Associate Professor, at the above address. Work on this paper was begun while the author was an Associate Professor in the Faculty of Education at Simon Fraser University.