Retardation and twin concordance in infant mental development: a reassessment

A reappraisal is made of Nichols and Broman's conclusion that there is no evidence that genetic influences are important in infant mental development if severely retarded twins are excluded from the sample. The reappraisal touches on certain idiosyncrasies of their sample, the test scores reported, and their definition of severe retardation. Data are presented for a sample of White twins who have been followed longitudinally since birth. For Bayley Mental Scale scores at 9 months of age, the monozygotic within-pair correlation was 0.85 and the dizygotic within-pair correlation was 0.62. With 13 retarded twins excluded, the correlations became 0.81 and 0.64, respectively, with the monozygotic correlation still being significantly larger (p less than 0.01). The present results indicate that genetic factors play a role in infant mental development.     

Eight-year follow-up of cognitive development in 33 twin pairs

This is a follow-up study of twins, including 33 twinpairs from the Stockholm area, aiming to study the cognitive development of twins at eight years of age. The twins have been followed at different ages from birth onwards. All children were tested with the Wechsler Intelligence Scale for Children in a Swedish translation (WISC). The WISC test consists of a Verbal and a Performance Scale. There were no significant differences between twin girls and twin boys on these Scales. On the Performance subtests Block Design, Object Assembly, and Coding, however, the twin girls performed significantly better than the twin boys. In comparing cognitive development for twins and singletons, the twin group had somewhat lower average scores than the singletons. Prematurity and low birth weight continued to be related to cognitive development at eight years of age. Also at this age the school teacher completed a questionnaire about the twins social behaviour and some personality traits. There was a relation between one questionnaire factor, a low score of assertiveness, and the mother's negative or ambivalent expectations concerning the twin pregnancy. The twin group with the mother's negative expectations also had significantly lower results on the subtests Comprehension and Coding. Negative mothers had more premature twins than mothers who were positive toward the twin pregnancy.     

Twins: Mental development in the preschool years.

Obtained measures of mental development (Wechsler Preschool and Primary Scale of Intelligence, Bayley Scales of Infant Development, and the Stanford-Binet Intelligence Scale) for a large sample of over 350 pairs of twins from 11/2 to 6 yrs of age. Initially the twins were somewhat depressed in developmental status, but they ultimately reached parity with singletons by age 6. The age-to-age predictive correlations followed the typical simplex pattern of declining as the age span increased but still remained higher for the Bayley Scales than had previously been reported. Sex differences were also noted for the pattern of age-to-age correlations. Monozygotic twins were significantly more concordant than dizygotic twins for the measures of mental development at each age and for the changes in relative precocity between ages to age 5. By that age, the measures of intelligence had stabilized to the point where year-to-year changes were no longer a significant source of variance. Parental education and socioeconomic status gave modest positive correlations with the twins' IQ scores at age 6. Results point to the genetic blueprint as the principal determinant of childhood mental development for the broad range of home environments represented in this study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Factor analysis of WISC—R with deaf and hard-of-hearing children.

The Wechsler Intelligence Scale for Children—Revised (WISC—R) was factor analyzed on a sample of 368 hard-of-hearing and deaf children (aged 6–16 yrs). Two factors emerged and were labeled Language Comprehension and Visual-Spatial Organization. The factor structure for the hard-of-hearing (n?=?77) and deaf (n?=?291) groups was identical. Deaf children of deaf parents earned significantly higher Verbal IQ and Performance IQ scores than did deaf children of hearing parents. There were no differences in IQ or subtest scores in interpreted vs signed administrations. Implications for assessing the cognitive abilities of hearing-impaired children are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Risk and resilience in early mental development.

Examined mental development scores for 2 groups of at-risk twins throughout their childhood, those classified as small for gestational age (SGA), and those twins falling below 1,750 g birthweight. The Ss were recruited as newborns—about 30 new pairs were added each year—and the total sample included 450 pairs of twins. Ss were assessed using the Bayley Scales of Infant Development at age 24 mo and the WPPSI at age 6 yrs. Results show that the SGA Ss showed only a modest deficit in IQ scores as compared to the full twin Ss, and thus these small-for-date Ss did not appear to be at special risk. The Ss below 1,750 g, however, did show a very significant deficit in IQ scores throughout childhood. When the recovery patterns were examined for this group, upper SES Ss appeared to recover completely, whereas lower SES Ss remained significantly depressed. Mother's education was significantly related to recovery from 24 mo onward, which suggests that maternal intelligence plays a prominent role in determining the level of recovery. When monozygotic Ss of markedly unequal birth weight were compared, the twins who weighed less than 1,750 g attained the same level of IQ scores at 6 yrs as did their heavier co-twins. Among these genetic replicates, the initially powerful effects of low birth weight did not exert a long-term handicapping effect on mental development. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Two types of tables for use with the WAIS-R.

Confidence intervals for the WAIS-R were computed for the Verbal, Performance, and Full Scale IQ scores. IQ intervals for the 85, 90, 95, and 99% levels of confidence are reported for each of the 9 standardization sample age groups and the entire sample. Differences between Verbal and Performance IQ scores required for 90 and 99% levels of significance are also reported. All values are computed on the basis of the standard errors of measurement reported in the WAIS-R manual for the standardization sample. (5 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Luria-Nebraska Neuropsychological Battery—Children's Revision: Concurrent validity with three learning disability subtypes.

Concurrent validity of the Luria-Nebraska Psychological Battery—Children's Revision (LNNB—C) was studied in 82 learning disabled children who were divided into three groups according to Verbal and Performance IQ differences on the Wechsler Intelligence Scale for Children—Revised (WISC—R). The three groups, comparable in age and on WISC—R Full-Scale IQ scores, were designated auditory-linguistic (Verbal IQ?     

A longitudinal study of cognitive abilities and educational attainment in Williams syndrome

The paper reports on changes in IQ scores and in reading, spelling and arithmetic skills over time in 23 young adults with Williams syndrome. They were first assessed in their early to mid-teens and followed up 8 to 9 years later, at an average age of 21 years 9 months. Cognitive assessments indicated increases in Full Scale, Verbal and Performance IQ scores. These increases allow us to conclude that in the case of Williams syndrome (unlike some other conditions) there does not appear to be a decline in the rate of cognitive development over time. Comparisons of Reading, Spelling and Arithmetic scores attained at first and second testing periods revealed only modest increases in reading accuracy and spelling scores, a slight decline in reading comprehension scores, and little change in arithmetic test scores. Differences in the tests used at the two assessment periods do not allow for definitive conclusions to be drawn, but the findings suggest that individuals with Williams syndrome make little progress in their educational skills beyond their early teenage years.     

Comparison of the performance of matched groups of black children and white children on the Wechsler Preschool and Primary Scale of Intelligence.

Compared the Wechsler Preschool and Primary Scale of Intelligence Verbal, Performance, and Full Scale IQs of blacks and whites who were matched on age, sex, geographic region, father's occupation, and urban-rural residence. A group of 132 4-61/2 yr old pairs was obtained from the standardization sample of 1,044 whites and 156 blacks. The whites had significantly higher Verbal and Full Scale IQs at all age levels. Performance IQ, however, was significantly higher for the whites in the youngest group (ages 4-41/2) but not for those aged 5-51/2 and 6-61/2. Results are compared to previous findings, and implications are discussed in term of perceptual experiences. (18 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mental development: Concordance for same-sex and opposite-sex dizygotic twins.

Administered the Bayley Scales of Infant Development, the Stanford-Binet Intelligence Scale, the McCarthy Scales of Children's Abilities, and the Wechsler Preschool and Primary Scale of Intelligence to 375 same-sex and opposite-sex dizygotic (DZ) twins from 3 mo–6 yrs of age. With 1 exception (9 mo), there was no significant difference in concordance at any age for same-sex and opposite-sex twins. In both groups, the within-pair correlations increased during early childhood to a maximum value at 3 yrs, then gradually regressed at 6 yrs. Data provide no evidence of greater discordance among opposite-sex twins for mental development in the preschool years. It is concluded that sex differences may be set aside as a nonsignificant factor in the concordance estimates for DZ twins. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Verbal-performance IQ discrepancies on the WISC-R.

Examined discrepancy scores (Verbal IQ minus Performance IQ) for the WISC-R, using the standardization sample--100 boys and 100 girls at each of 11 age levels between 61/2 and 161/2 yrs (2,200 Ss). The occurrence of significant discrepancy scores (Verbal > Performance and Performance > Verbal) was not significantly related to age, sex, or race, although significant relationships were obtained with both parental occupation and intelligence level. The mean absolute discrepancy score (regardless of sign) was about 10 IQ points for each age group, for boys and girls, for Blacks and Whites, and for the different occupational groups. Discrepancy score norms (cumulative distributions) are presented by intelligence level and are interpreted in terms of their clinical significance. Several of these findings closely parallel results of a study of the 1949 WISC by H. G. Seashore (see record 1952-06292-001). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Speech and language development of children born at < or = 32 weeks' gestation: a 5-year prospective follow-up study

Speech and language comprehension and production were assessed at the age of 5 years in a cohort of children born preterm at < or = 32 weeks' gestational age (N=55) in comparison with children born at term and of similar age, sex, and social backgrounds. Data both including and excluding major neurological disabilities are presented. Mean performance for the entire group of preterm children was significantly lower than for the controls on most of the measures including the composite IQ scores. When the nine children who had major neurological disabilities were excluded from the preterm group, statistically significant differences were found on four of the total 12 speech and language measures. Intellectually normal preterm children without major neurological disability were slower than the controls on rapid word retrieval. In addition, difficulties in comprehending relative concepts were typical for the preterm children. The results suggest 'subtle dysnomia', which is indicative of later reading problems. On global verbal measures and on the basic speech and language aspects the study groups did not differ. Specific language impairment, defined as a discrepancy of > 1SD between Performance IQ and Verbal IQ scores, showed a tendency to be more common in the control group. Within both the study groups, the boys showed a tendency for a greater discrepancy between their Performance and Verbal IQ scores.     

Processes by which verbal-educational abilities are affected when mothers encourage preschool children to verbalize.

Devised a measure of mothers' (20–36 yrs old) encouragement of child-generated verbal responses from videotapes of 66 mothers teaching a block-sorting task to their children. Mothers were administered the WAIS, and children received the Peabody Picture Vocabulary Test and the Wechsler Preschool and Primary Scale of Intelligence at 3–6 yrs of age. Correlations and partial correlations of mothers' encouragement of verbalization with children's knowledge of letters and numbers were significantly stronger than those with Verbal and Performance IQ, which were nonsignificant. It is concluded that this pattern of correlations is consistent with a specific verbalization-helps-memory-of-content mechanism and inconsistent with a more global verbalization-generally-helps-thinking mechanism. (57 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Validity of the Luria-Nebraska Intellectual Processes Scale as a measure of adult intelligence.

Luria-Nebraska Intellectual Processes Scale (IPS) scores were correlated with the 3 WAIS IQs of 33 right-handed psychiatric patients (mean age 41 yrs), and regression equations were computed to obtain estimated Verbal IQ, Performance IQ, and Full Scale IQ using the IPS as the predictor variable. Mean differences between estimated IQs and the WAIS IQs were nonsignificant. There was high agreement with respect to the classification into normal vs subnormal levels of intelligence. (3 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Efficacy of the Satz-Mogel short form WAIS—R for tumor patients with lateralized lesions.

The ability of the P. Satz and S. Mogel (1962) short form Wechsler Adult Intelligence Scale—Revised (WAIS—R) to provide equivalent information about IQ scores and age-corrected scale scores was examined as a function of side of lesion for 34 left hemisphere damaged (LHD) and 29 right hemisphere damaged (RHD) patients having primary brain tumors. Correlations between the 2 forms were significant for all WAIS—R scores with the exception of the Object Assembly subtest for RHD patients. The short form significantly overestimated Verbal IQ, Performance IQ, Full Scale IQ, Similarities, and Picture Arrangement subtest scores. It significantly underestimated Object Assembly subtest scores. A marked percentage of patients showed 1 or more category changes for most WAIS—R scores and 2 or more category changes for some of these scores. The distribution of discrepancies between scores and the number of category changes did not differ significantly for LHD and RHD patients. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory failures in progressive idiopathic dementia.

14 patients with progressive idiopathic dementia (PID) were compared with 14 normal controls (average age 61.2 yrs) on psychometric and laboratory measures of cognitive processes. Patients had significantly lower scores than controls on the Wechsler Memory Scale and the WAIS Performance IQ, but not on WAIS Verbal or Full Scale IQ or Digit Span tests. Patients performed more poorly on learning and memory tasks than controls. Unlike the latter, patients' recall of categorized word lists was no better than their recall of unrelated words, and they did not consistently remember information that had been previously recalled. Patients also were unable to generate as many words that start with a given letter or that belong to a given category as controls did. Data show that while many intellectual functions are preserved, PID patients are unable to access structures in semantic memory and therefore fail to effectively encode episodic events so that they are memorable. Differences in cognitive dysfunction in PID and in depression are discussed. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

WAIS—R abbreviated forms in the elderly: A comparison of the Satz-Mogel with a seven-subtest short form.

The Satz-Mogel abbreviation of the Wechsler Adult Intelligence Scale—Revised (WAIS—R) was compared with a 7-subtest short form (L. C. Ward, see record 1991-00137-001) in samples of normal and neurologically impaired elderly persons 75 yrs and older. The normals were 130 Ss from the old-age WAIS—R standardization sample, and the brain-damaged group consisted of 40 men with medically diagnosed brain dysfunction (average age 79.5 yrs). The short forms were highly similar in administration times, correlations with the WAIS—R IQs, estimation of the average IQ scores, and in classification of intelligence for both the normal and neurologically impaired Ss. Finally, both short forms correctly estimated significant Verbal IQ–Performance IQ discrepancies about 75% of the time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

WISC-R subscale patterns of abilities of Blacks and Whites matched on Full Scale IQ.

270 Black and 270 White children (ages 6–16.5 yrs) drawn from the national stratified random sample used in the standardization of the WISC-R were matched on age, sex, and WISC-R Full-Scale IQ to facilitate investigation of the patterns of specific cognitive abilities, as measured by the 12 subtests of the WISC-R, between the 2 racial groups. Multivariate analysis of the patterns of subtest differences between Whites and Blacks and group comparisons on 3 orthogonalized factor scores (Verbal, Performance, Memory) showed small but reliable average White–Black differences in patterns of ability. The IQ-matched racial groups showed no significant difference on the Verbal factor; Whites exceeded Blacks on the Performance (largely spatial visualization) factor; Blacks exceeded Whites on the Memory factor. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Children with in utero cocaine exposure do not differ from control subjects on intelligence testing

OBJECTIVE: To determine if in utero cocaine exposure affects IQ scores in children at age 4 years. DESIGN: A prospective, longitudinal evaluation by blinded examiners of the IQ scores of cocaine-exposed and control children of low socioeconomic status who have been observed since birth. SETTING: A study center in an inner-city hospital. PARTICIPANTS: One hundred one children with in utero cocaine exposure and 118 control children, all of whom were 34 weeks' gestational age or older and nonasphyxiated at birth. MAIN OUTCOME MEASURE: Intelligence quotient scores on a standardized intelligence test, the Wechsler preschool and Primary Scale of Intelligence--Revised. RESULTS: Seventy-one cocaine-exposed and 78 control children were administered the Wechsler Preschool and Primary Scale of Intelligence--Revised. Maternal, natal, and 30-month characteristics of the children tested did not differ from those not tested. Groups did not differ on mean Performance (83.2 vs 87.0), Verbal (79.0 vs 80.8), or Full Scale (79.0 vs 81.9) IQ scores (all P > or = .10 [values for cocaine-exposed children given first]). None of these 3 scores was associated with cocaine exposure in multivariate linear regressions. Although cocaine-exposed and control groups did not differ in outcome, 93% of cocaine-exposed and 96% of control children had Full Scale IQ scores below 100, the mean IQ score for the test. CONCLUSIONS: In an inner-city cohort, IQ scores did not differ between cocaine-exposed and control children. However, both groups performed poorly.     

Further appraisal of the Verbal scale as a short form of the WAIS.

Verbal IQ from the WAIS has been found to overestimate Full Scale IQ, and consequently, the Verbal scale has been judged unsatisfactory as a WAIS short form. To investigate this question further, a regression equation relating Verbal and Full Scale IQs was derived from the scores of 100 psychiatric and medical patients and was cross-validated on a 2nd sample (40 Ss from the same S pool). In both groups, scores were highly correlated, and Verbal IQ significantly exceeded Full Scale IQ. Regression estimates, however, closely estimated mean Full Scale IQ, suggesting that the Verbal scale can serve effectively as a WAIS abbreviation. (2 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)