A longitudinal study of bilingual and cognitive development(1)

This paper presents the findings of a longitudinal study of IQ data collected over a 5-year period (Grades K-4) on pupils enrolled in a French immersion program (anglophone pupils receiving all instruction in French except English language arts) and pupils in the regular English program. Although year-by-year results may fail to show IQ differences between the two groups, repeated measures analysis indicates that the immersion group has a higher IQ measure over the 5-year period. However, considering Grades 1–3 only, which involved the administration of the same test, the two groups do not score differentially with respect to either overall IQ measure or specific subtest scores (classification/categorization, analogies, following of verbal directions) when scores are adjusted for initial IQ (and age) differences, thus failing initially to support studies which show positive relationships between bilingualism and cognitive functioning. However, supportive of those studies is a further analysis on the data of immersion pupils classified as “high” French achievers vs. “low” French achievers. The high French achievers obtain significantly higher IQ measures and subtest scores (analogies and following of verbal directions) than the low French achievers, even when scores are adjusted for initial IQ and age differences. These findings are interpreted in the context of Cummins' (1976) “threshold” hypothesis relating to level of competence in the second language.     

Are apparent sex differences in mean IQ scores created in part by sample restriction and increased male variance?

This study investigated the possibility that apparent sex differences in IQ are at least partly created by the degree of sample restriction from the baseline population. We used a nationally representative sample, the 1970 British Cohort Study. Sample sizes varied from 6518 to 11,389 between data-collection sweeps. Principal components analysis of scores obtained on four cognitive tests administered at age 10 was used to obtain estimates that we name ‘IQ’. These age-10 scores were then used to estimate the sex differences at age 10, and also among participants in the two later waves, at age 26 and 30. At age 10, there was a small but significant advantage for boys (Cohen’s d = 0.081). Boys had greater variability in these IQ scores. We then investigated how this very small male advantage at 10 changed with sample restriction. We used the same IQs obtained at age 10, but considered only those subjects who returned for data-collection sweeps at ages 26 and 30 years. Subjects returning at age 26 and 30 were more likely to be females and to have higher age-10 IQ scores. Attrition at age 30 was 28% and the male advantage in IQ scores increased by 15%. Attrition at age 26 was 43% and the male advantage in IQ scores increased by 48%. The findings underline the importance of monitoring attrition in longitudinal studies, as well as emphasising the need for representative samples in studying sex differences in intelligence. A proportion of the apparent male advantage in general cognitive ability that has been reported by some researchers might be attributable to the combination of greater male variance in general cognitive ability and sample restriction, though this remains to be tested in a sample with an appropriate mental test battery.     

The rise and fall of IQ in special ed: Historical trends and their implications

Using IQ records from 10 sites around the country, we examined longitudinal trends in IQ among mental retardation (MR) students during the Wechsler Intelligence Scale for Children (WISC) to WISC-Revised (R) transition in the 1970s and learning disability (LD) students during the WISC-R to WISC-3rd Revision (III) transition in the 1990s. Based on the work by Flynn [American Journal of Mental Deficiency 90 (1985) 236; Psychology, Public Policy, and Law 6 (2000) 191], we predicted a rise in IQ followed by a fall each time a newly normed IQ test is introduced into the schools and used to diagnose children as MR or LD. As expected, we found that mean IQs of MR and LD students followed a nearly identical parabolic trajectory, and differed depending on what year they were tested. IQs from the older norms were higher than IQs from the newly introduced norms. This systematic shift had a significant impact on the likelihood of a MR diagnosis. The broader implications of this pattern are discussed.     

Variations in WISC-R patterns of learning disabled children

The WISC-R was administered to 19 learning disabled students at the time of diagnosis and following a period of time in special program placements. Group analyses indicated fluctuations between testing times in the Verbal and Full-Scale IQs and the V-P IQ discrepancies. Small but significant differences in Verbal, Performance and V-P scatter indices were observed at one or both testings in comparison to the normal standardization sample. Although the suggested group pattern for learning disabled children based on the Bannatyne categories was confirmed on both occasions, there was considerable variation for individual subjects.     

Health‐adjusted neuropsychological test norms based on 463 older Swedish car drivers

There is a need for improved normative information in particular for older persons. The present study provides neuropsychological test norms on seven cognitive tests used in a sample representing the general older driving population, when uncontrolled and controlled for physical health. A group of 463 healthy Swedish car drivers, aged 65 to 84 years, participated in a medical and neuropsychological examination. The latter included tests of visual scanning, mental shifting, visual spatial function, memory, reaction time, selective attention, and simultaneous capacity. Hierarchical regression analyses demonstrated that, when uncontrolled for health, old age was associated with significant impairment on all seven tests. Education was associated with a significant advantage for all tests except most reaction time subtests. Women outperformed men on selective attention. Controlling for health did not consistently change the associations with education, but generally weakened those with age, indicating rises in normative scores of up to 0.36 SD (residual). In terms of variance explained, impaired health predicted on average 2.5%, age 2.9%, education 2.1% and gender 0.1%. It was concluded (1) that individual regression‐based predictions of expected values have the advantage of allowing control for the impact of health on normative scores in addition to the adjustment for various demographic and performance‐related variables and (2) that health‐adjusted norms have the potential to classify functional status more accurately, to the extent that these norms diverge from norms uncontrolled for physical health.     

An exploratory analysis of American Indian children's cultural engagement, fluid cognitive skills, and standardized verbal IQ scores

This exploratory cross-sectional study examined fluid cognitive skills and standardized verbal IQ scores in relation to cultural engagement amongst Tohono O'odham children (N = 99; ages 7 to 12 years). Guardians with higher socioeconomic status engaged their children in more cultural activities, and participation in more cultural activities contributed to higher standardized verbal IQ scores. Mean cognitive skill scores varied as a function of age and Tohono O'odham language knowledge. Children who understood and/or spoke Tohono O'odham started out with lower average scores than did children with no language knowledge, but mean scores generally increased in the older age groups such that they were equal to or higher than those of nonspeakers by age 9. Children with higher fluid cognitive skill scores had higher standardized verbal IQ scores than did children with lower scores.     

Cognitive,emotional and social development in adolescents born to substance using women

The aim of this article is to investigate the long‐term developmental consequences of being born to a substance‐using mother, focusing on cognitive functions, attention, emotional and social development. The longitudinal sample comprised 48 adolescents aged 12–16 at the time of follow‐up assessments, which included the Wechsler Intelligence Scale for Children‐III, the Test of Everyday Attention for Children, The Tower of London test and the Strengths and Difficulties Questionnaire. The adolescents scored significantly lower than the norms on Wechsler's subtests and Full‐Scale IQ, and on The Everyday Attention test. There were few differences on the Strengths and Difficulties Questionnaire. The girls reported significantly more hyperactivity than the British norms, and the teachers reported higher impact scores in boys, compared to the British norms. Thus, the results on cognitive consequences of maternal substance use appear to be very substantial while the emotional and social consequences do not. The results suggest serious negative effects of substance exposure in utero on attention and cognitive functioning in general.     

The woodcock reading mastery test: impact of normative changes

This study examined the magnitude of differences in standard scores, convergent validity, and concurrent validity when an individual's performance was gauged using the revised and the normative update (Woodcock, 1998) editions of the Woodcock Reading Mastery Test in which the actual test items remained identical but norms have been updated. From three metropolitan areas, 899 first to third grade students referred by their teachers for a reading intervention program participated. Results showed the inverse Flynn effect, indicating systematic inflation averaging 5 to 9 standard score points, regardless of gender, IQ, city site, or ethnicity, when calculated using the updated norms. Inflation was greater at lower raw score levels. Implications for using the updated norms for identifying children with reading disabilities and changing norms during an ongoing study are discussed.     

Developmental trajectories in toddlers' self-restraint predict individual differences in executive functions 14 years later: a behavioral genetic analysis

We examined whether self-restraint in early childhood predicted individual differences in 3 executive functions (EFs; inhibiting prepotent responses, updating working memory, and shifting task sets) in late adolescence in a sample of approximately 950 twins. At ages 14, 20, 24, and 36 months, the children were shown an attractive toy and told not to touch it for 30 s. Latency to touch the toy increased with age, and latent class growth modeling distinguished 2 groups of children that differed in their latencies to touch the toy at all 4 time points. Using confirmatory factor analysis, we decomposed the 3 EFs (measured with latent variables at age 17 years) into a Common EF factor (isomorphic to response inhibition ability) and 2 factors specific to updating and shifting. Less-restrained children had significantly lower scores on the Common EF factor, equivalent scores on the Updating-Specific factor, and higher scores on the Shifting-Specific factor than did the more-restrained children. The less-restrained group also had lower IQ scores, but this effect was entirely mediated by the EF components. Twin models indicated that the associations were primarily genetic in origin for the Common EF variable but split between genetics and nonshared environment for the Shifting-Specific variable. These results suggest a biological relation between individual differences in self-restraint and EFs, one that begins early in life and persists into late adolescence.     

Constructing local age norms based on ability for the Bender-Gestalt test

The purpose of this study was to examine developmental patterns in visuomotor functioning across age and ability groups. A second purpose was to develop local norms to allow practicing psychologists to examine relative differences within age and IQ groups in visuomotor performance. Thus, an age-by-mental ability normative data set (N=4,014) was constructed from archival records from 10 public school systems and analyzed to identify both qualitative and quantitative differences in visuomotor functioning for children between 6 and 18.11 yr. of age across 9 IQ levels ranging from 40 to 129.     

Wais-III norms for working-age adults: a benchmark for conducting vocational, career, and employment-related evaluations

The Wechsler Intelligence Scales are routinely used to assess threshold variables which correlate with subsequent job performance. Intellectual testing within educational and clinical settings accommodates natural developmental changes by referencing results to restricted age-band norms. However, accuracy in vocational and career consultation, as well as equity in hiring and promotion requires the application of a single normative benchmark unbiased by chronological age. Such unitary norms for working-age adults (18- to 64-yr.-olds) were derived from the WAIS-III standardization sample in accord with the proportional representation of the seven age-bands subsumed within this age range. Tabular summaries of results are given for the conversion of raw scores to scaled scores for the working-age population which can be used to derive IQ values and Index Scores.     

Individual differences in trajectories of arithmetical development in typically achieving 5- to 7-year-olds

The arithmetical performance of typically achieving 5- to 7-year-olds (N = 29) was measured at four 6-month intervals. The same seven tasks were used at each time point: exact calculation, story problems, approximate arithmetic, place value, calculation principles, forced retrieval, and written problems. Although group analysis showed mostly linear growth over the 18-month period, analysis of individual differences revealed a much more complex picture. Some children exhibited marked variation in performance across the seven tasks, including evidence of difficulty in some cases. Individual growth patterns also showed differences in developmental trajectories between children on each task and within children across tasks. The findings support the idea of the componential nature of arithmetical ability and underscore the need for further longitudinal research on typically achieving children and of careful consideration of individual differences.     

Are All Kids Alike? The Magnitude of Individual Differences in Personality Characteristics Tends to Increase from Early Childhood to Early Adolescence

Do individual differences in personality traits become more or less pronounced over childhood and adolescence? The present research examined age differences in the variance of a range of personality traits, using parent reports of two large samples of children from predominantly the USA and Russia, respectively. Results indicate (i) that individual differences in most traits tend to increase with age from early childhood into early adolescence and then plateau, (ii) that this general pattern of greater personality variance at older childhood age is consistent across the two countries, and (iii) that this pattern is not an artefact of age differences in means or floor/ceiling effects. These findings are consistent with several (noncontradictory) developmental mechanisms, including youths' expanding behavioural capacities and person–environment transactions (corresponsive principle). However, these mechanisms may predominantly characterize periods before adolescence, or they may be offset by countervailing processes, such as socialization pressure towards a mature personality profile, in late adolescence and adulthood. Finally, the findings also suggest that interpreting age trajectories in mean trait scores as pertaining to age differences in a typical person may sometimes be misleading. Investigating variance should become an integral part of studying personality development. Copyright © 2017 European Association of Personality Psychology     

The role of processing resources in age-related prospective and retrospective memory within old age

This study investigated the role of processing speed and working memory in prospective and retrospective memory (i.e., free recall) performance within old age. The aim was to examine age-related differences in both memory domains within the age range of 65 to 80 years. The sample consisted of 361 older adults from Wave 1 data of the Zurich Longitudinal Study on Cognitive Aging. Using structural equation modeling, prospective memory, free recall, working memory, and processing speed were identified as latent constructs. Age effects were found to be larger for prospective memory than for free recall. Furthermore, when controlling for individual differences in working memory and processing speed, unique age effects remained for prospective, but not retrospective, memory performance. Results indicate that, within old age, prospective memory represents a distinct memory construct that is partially independent of age-related individual differences in speed of processing, working memory, and retrospective memory.     

A comparison of children with epilepsy to an age- and IQ-matched control group on the Children's Memory Scale.

Past research has found that children with epilepsy exhibit decreased memory skills. In addition, some studies have found that children with epilepsy obtain significantly lower IQ scores than controls. In an effort to examine whether children with epilepsy have specific memory weaknesses versus global cognitive difficulties, the present study compared the performance of 62 children (age range = 6-16 years). Thirty-one children with epilepsy were compared to 31 age- and IQ-matched controls on the Children's Memory Scale (CMS) to determine whether differences in memory skills persist when IQ is matched. An independent t-test comparing index and scaled scores was performed. The results indicated that with the exception of the Word Pairs subtest (p < .01), children with epilepsy did not differ significantly on the CMS subtests when IQ was matched. This suggests that list-learning paradigms may be particularly sensitive to memory impairments in children with epilepsy and/or that children with epilepsy have more global cognitive impairments.     

A Comparison of Children with Epilepsy to an Age- and IQ-Matched Control Group on the Children's Memory Scale

Past research has found that children with epilepsy exhibit decreased memory skills. In addition, some studies have found that children with epilepsy obtain significantly lower IQ scores than controls. In an effort to examine whether children with epilepsy have specific memory weaknesses versus global cognitive difficulties, the present study compared the performance of 62 children (age range = 6–16 years). Thirty-one children with epilepsy were compared to 31 age- and IQ-matched controls on the Children's Memory Scale (CMS) to determine whether differences in memory skills persist when IQ is matched. An independent t-test comparing index and scaled scores was performed. The results indicated that with the exception of the Word Pairs subtest (p < .01), children with epilepsy did not differ significantly on the CMS subtests when IQ was matched. This suggests that list-learning paradigms may be particularly sensitive to memory impairments in children with epilepsy and/or that children with epilepsy have more global cognitive impairments.     

Modeling Intraindividual Cognitive Change in Aging Adults: Results from the Einstein Aging Studies

This paper reviews research from the longitudinal Einstein Aging Studies (EAS) that has focused on modeling intraindividual cognitive change in aging adults. We describe how to separate models of intraindividual change at the within-person level from models of individual differences in change at the between-person level. We illustrate this distinction by analyzing new data from the EAS to test the speed hypothesis at the intraindividual level of analyses. The present findings replicate those of Sliwinski and Buschke (1999) by showing that within-person changes in speed predict within-person changes in cognition, but that speed does not substantially attenuate estimates of within-person cognitive decline. We conclude that correct measurement and explanatory modeling of intraindividual change should be the primary focus of longitudinal aging research, and that the more common practice of modeling individual differences in change should be a secondary focus.     

Effects on WAIS-III performance IQ (PIQ) and full scale IQ (FSIQ) when object assembly is substituted for each standard performance scale subtest

According to the WAIS-III Administration and Scoring Manual, Object Assembly (OA) may be substituted for any spoiled Performance subtest. This assertion has not been evaluated in a clinical sample. The present investigation reports differences that resulted in Performance IQ (PIQ) and Full Scale IQ (FSIQ) when OA replaced each of the Performance subtests. Participants were 47 referrals for neuropsychological assessment (age M = 45.98 years, SD = 9.82; education M = 13.82 years, SD = 2.78). Results indicated that OA may replace any Performance subtest without seriously altering the summary scores. Differences between the standard IQs and OA-based composites were < 2 points for PIQ and < 1 point for FSIQ. More than 90% of the OA-based composites fell within the 90% confidence limits of the corresponding IQ.     

Do the Wechsler scales underestimate the difference between verbal and performance abilities in children with language–related disorders?

The present paper examines the validity of the Wechsler scales with children with language-related disorders, with whom the scales were not originally normed. The general question is whether we can take measures of IQ, normed with a normal sample, and then validly use them as indicators of the same constructs with samples significantly different from the normed sample. In previous papers it was pointed out that the pattern structurally simple > moderately complex > complex tests can be observed in their IQ profiles within both the Verbal scale and the Performance scale. In this paper, it is hypothesized that this scatter of scores leads to an underestimation of the global V-P IQ differences for children with language-related disorders because there are more structurally complex tests on the Performance scale than on the Verbal scale. To test this hypothesis, "purer" V-P IQ differences were calculated by comparing the scores on Verbal and Performance tests of equal structural complexity. WPPSI and WISC-R data from four groups of children were analyzed: language-impaired children (n = 128), reading-impaired children (n = 112), children from dyslexic families (n = 51), and normal children (n = 49). When the effect of the difference in structural complexity was controlled for, it was found that the distribution of the revised V-P IQ difference was significantly more toward the negative end of the spectrum than the traditional V-P IQ differences for language-impaired and reading-impaired children, and approaching a significant level for children from dyslexic families. As hypothesized, there were no significant differences between the two distributions of V-P IQ differences for normal children. Practical and theoretical implications are discussed.