The Factor Structure of the WAIS-R: Replicability Across Age-Groups

This article examines the factor structure of the Wechsler Adult Intelligence Scale- Revised across nine age groups using several methods of factor analysis, including reliable component analysis (RCA). RCA defines orthogonal components which have maximum reliability, and has several desirable properties which are discussed. Although the one- factor model (General Intelligence, or g), and the two-factor model (Verbal and Performance) of the WAIS-R are fairly well established. no such consensus has been reached regarding the three-factor model (Verbal Comprehension. Perceptual Organization, and Freedom from Distractibility). In the present study, g and Verbal and Performance factors were consistent across age groups for most methods of extraction, although somewhat different from the usual division. The three-factor model, however, was not consistently identified across age groups by any method, particularly with respect to Freedom from Distractibility. Meaningful interpretation of scores on this factor is therefore tenuous. RCA performed well, relative to most other methods, in identifying factors consistently across age groups and can provide useful and unique information.     

Factor structure of the Norwegian version of the WAIS-III in a clinical sample: the arithmetic problem

Confirmatory Factor Analyses (CFA) of the Wechsler Adult Intelligence Scale-III (WAIS-III) lend partial support to the four-factor model proposed in the test manual. However, the Arithmetic subtest has been especially difficult to allocate to one factor. Using the new Norwegian WAIS-III version, we tested factor models differing in the number of factors and in the placement of the Arithmetic subtest in a mixed clinical sample (n = 272). Only the four-factor solutions had adequate goodness-of-fit values. Allowing Arithmetic to load on both the Verbal Comprehension and Working Memory factors provided a more parsimonious solution compared to considering the subtest only as a measure of Working Memory. Effects of education were particularly high for both the Verbal Comprehension tests and Arithmetic.     

Validity of the Wechsler abbreviated scale of intelligence and other very short forms of estimating intellectual functioning

Performance on the Wechsler Adult Intelligence Scale-III (WAIS-III) was compared to performance on the Wechsler Abbreviated Scale of Intelligence (WASI), as well as short form estimations of intellectual functioning derived from WAIS-III performance, in a mixed clinical sample of 72 participants. The WASI verbal IQ (VIQ) score was significantly higher than the WAIS-III VIQ, whereas performance IQ (PIQ) estimates all differed from actual WAIS-III PIQ and full scale IQ (FSIQ). Correlations of WAIS-III scores with WASI scores were consistently lower than were correlations between the WASI-III and all other short forms. Although maintaining administration times of 15 minutesfor a two-subtest FSIQ and 30 minutes for a four-subtest FSIQ, the WASI did not consistently demonstrate desirable accuracy in predicting scores obtained from the WAIS-III. The results suggest that clinicians should use the WASI cautiously if at all, especially when accurate estimates of individuals' WAIS-III results are needed.     

Factor analysis of Wechsler Adult Intelligence Scale-Revised in developmentally disabled persons

The results of previous studies on the factorial structure of Wechsler Intelligence Scales are somewhat inconsistent across normal and pathological samples. To study specific clinical groups, such as developmentally disabled persons, it is useful to examine the factor structure in appropriate samples. A factor analysis was carried out using the principal component method and the Varimax orthogonal rotation on the Wechsler Adult Intelligence Scale (WAIS-R) in a sample of 203 developmentally disabled persons, with a mean age of 25 years 4 months. Developmental disability ranged from mild to moderate. Partially contrasting with previous studies on normal samples, results found a two-factor solution. Wechsler's traditional Verbal and Performance scales seems to be more appropriate for this sample than the alternative three-factor solution.     

Relation of cognitive functioning to daily living skills in a geriatric population

A modified version of the Community Competence Scale was administered along with the Wechsler Adult Intelligence Scale--Revised (WAIS--R) to 40 geriatric patients with suspected dementia. Scores on the Competence Scale, a measure of functional daily living skills, were correlated .72 with Full Scale IQs and .77 with Verbal IQs and moderately correlated (.55) with Performance IQs. A number of significant correlations were found between WAIS--R subtests and subscales of the competence instrument. Means and standard deviations for the 10 Competence subscale and total scores are presented.     

Use of the Peabody Picture Vocabulary Test with the educationally handicapped

Despite widespread use of the Peabody Picture Vocabulary Test (PPVT) as a measure of intelligence for educationally handicapped students, few studies have related PPVT scores of such students to their scores on the Wechsler Intelligence Scale for Children (WISC). Using 100 public school students consecutively referred for learning difficulties, their mean PPVT IQ (97.75) was found to be consistently and significantly higher than WISC Full Scale IQ (89.65), Verbal IQ (88.68), and Performance IQ (92.73). Correlations between the PPVT IQ and the WISC Full Scale, Verbal, and Performance IQs were .70, .69, and .54, respectively. A tabular summary of previous studies comparing PPVT and WISC IQs is included.     

Relationship of scores on PPVT-R and WISC-R with special education children and youth

Comparisons of the Peabody Picture Vocabulary Test-Revised and the Wechsler Intelligence Scale for Children-Revised were made with 104 children diagnosed as learning disabled and mentally retarded. Significant but modest correlations were found between all but one of the WISC-R scaled scores (i.e., Coding) and PPVT-R standard scores, and between WISC-R IQs and PPVT-R standard scores. Significant differences were found among mean Verbal, Performance, and Full Scale IQs and mean PPVT-R standard scores. The PPVT-R standard scores underestimated WISC-R Verbal IQs by 7 points, WISC-R Performance IQs by 17 points, and WISC-R Full Scale IQs by 11 points.     

Replication of the factor structure of the Wechsler Adult Intelligence Scale--Third Edition with a Canadian sample

Exploratory and confirmatory factor analyses of the subtests of the Wechsler Adult Intelligence Scale--Third Edition (WAIS-III; D. Wechsler, 1997b) were conducted on a stratified sample of Canadian adults (n = 718). As was previously demonstrated for the children's version of this scale, the factor model of the American standardization sample was replicated across this Canadian national sample. Results of the factor analyses confirmed the presence of the 4 WAIS-III factors: Verbal Comprehension, Perceptual Organization, Working Memory, and Processing Speed.     

The relationship between WAIS-R abilities and speed of processing in a word identification task

Matched to the proportions found in the U.K. census data for a range of demographic variables (age, sex, and socioeconomic status) 123 participants were tested on the Wechsler Adult Intelligence Scale-Revised (WAIS-R) and a test of the minimum presentation time required to identify tachistoscopically presented words. The correlations between the sum of the scaled scores for Full, Verbal, and Performance subtests and the log of the identification measures were -0.40, -0.22, and -0.51, respectively. These results are in line with those observed between the WAIS-R measures and standard visual inspection time (IT). Confirmatory factor analysis indicated that a three-factor model of intelligence with Verbal, Performance, and Attention/Concentration factors, and with the identification threshold loaded on the Performance factor alone, represented a better fit to the data than either a single general factor model or a two-factor model with Verbal and Performance factors. These results are in line with findings in the IT literature (Deary, 1993) that speed of information processing is significantly related to performance IQ but not to verbal IQ.     

Comparison of the Test of Nonverbal Intelligence and Wechsler Intelligence Scale for children--revised in rural Native American and white children

The Test of Nonverbal Intelligence (TONI) and Wechsler Intelligence Scale for Children--Revised (WISC--R) were administered to 46 Native American and white students who were suspected by their classroom teachers of having learning handicaps. Pearson correlations between these sets of IQs ranged from .42 (TONI and WISC--R Performance) to .89 (WISC--R Verbal and Full Scale).     

Estimation of Wechsler Adult Intelligence Scale-III index scores with the 7-subtest short form in a clinical sample

A 7-subtest short form of the Wechsler Adult Intelligence Scale-III (WAIS-III) previously demonstrated good comparability in estimating Full Scale and Verbal IQ summary scores, with adequate comparability in estimating Performance IQ. In a mixed clinical sample of 295 patients, the current study assessed the equivalence of the index scores generated from the full and prorated WAIS-III. The results revealed correlations corrected for redundancy of .90, .86, .87, and .75 for the Verbal Comprehension (VCI), Perceptual Organization (POI), Working Memory (WMI), and Processing Speed (PSI) indexes, respectively. Although the 7-subtest short form of the WAIS-III was not designed to estimate index scores, adequate estimates are viable for VCI, POI, and WMI when the goal is to obtain group, rather than individual, data points.     

A construct validation study of the Human Figure Drawing Test

To assess whether the Human Figure Drawing Test provides an assessment of nonverbal cognitive maturity, correlations for 31 youngsters who ranged in age from 6-0 to 10-10 on the Human Figure Drawing Test and the Verbal, Performance, and Full Scale IQs of the Wechsler Intelligence Scale for Children--Revised (WISC--R) were examined. Significant correlations were observed for each of the scales, but the value of .69 for drawings and WISC--R Performance IQs was significant, suggesting the assessment that these tests are largely nonverbal. Implications for the role of language were posited.     

Scoring reliability on the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III)

Nineteen psychologists and 19 graduate students scored two Wechsler Adult Intelligence Scale-Third Edition patient protocols. Mean IQs and indexes were similar across groups, but the ranges for Verbal IQ (VIQ), Performance IQ (PIQ), and Full Scale IQ (FSIQ) on one protocol were 25, 22, and 11 points, respectively. For both protocols taken together, percentages of agreement with the "actual" IQs for psychologists were only 26.3 for VIQ, 36.8 for PIQ, and 42.1 for FSIQ. For students, percentages were 15.8 for VIQ, 23.7 for PIQ, and 31.6 for FSIQ. The percentages of FSIQs that fell within +/- 1 standard error of measurement of the actual IQs were 89.5 for psychologists and 76.3 for students. Scoring error also had a negative impact on index scores. Both groups were confident about their scoring accuracy.     

Second-order confirmatory factor analysis of the WAIS-III. Wechsler Adult Intelligence Scale

According to Vernon's structure-of-intellect paradigm, abilities can be conceptualized as a hierarchy, with a factor of general intelligence at the top of the hierarchy, and successively more specific abilities toward the bottom. This paradigm has proven useful for interpreting a number of Wechsler intelligence scales. However, most of the research with this paradigm has used exploratory factor analysis, and the validity of the paradigm for the newest Wechsler Adult Intelligence Scale (WAIS-III) has yet to be evaluated. The present study examined the WAIS-III using second-order confirmatory factor analysis, which is a more appropriate analytic tool when specific hypotheses are tested. Using the standardization sample for the WAIS-III (N = 2,450), support was found for the hierarchical factor structure with a second-order factor of general intelligence and four first-order factors of Verbal Comprehension, Perceptual Organization, Working Memory, and Processing Speed.     

Two-subtest estimations of WAIS-III factor index scores

The reliability and validity of various short forms of the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III; D. Wechsler, 1997) were evaluated in a sample of 100 patients with traumatic brain injury and in a demographically matched subgroup from the standardization sample. All short forms were based on 2-subtest estimations of the respective factor indexes. Although acceptable estimates could be obtained from all short forms for Verbal Comprehension, none of the possible short forms for Perceptual Organization consistently met the minimum criterion regarding the percentage of cases that fell within the 90% confidence interval of the full-length index. It is concluded that short-form estimates of the WAIS-III are not appropriate for clinical use when the goal is to obtain factor indexes.     

Correlations for Wechsler Intelligence Scale for Children--Revised and the Wechsler Preschool and Primary Scale of Intelligence for Iranian children.

This study focused on the relationship between the Wechsler Intelligence Scale for Children--Revised (WISC--R) and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) given to 40 6-yr.-old Iranian children. Pearson correlations between the WISC--R and the WPPSI IQs and between scaled scores on the corresponding subtests were significant. The comparison of mean IQs and scaled scores indicates that the WISC--R yielded a significantly higher Verbal IQ and higher scores on Information, Vocabulary, Comprehension, and Picture Completion than the WPPSI. The mean difference between corresponding Verbal and Full Scale IQs was not significant. These results suggest that scores on the two instruments correlated well for these 6-yr.-old Iranian children and the content on which IQs for the recently restandardized WISC--R and WPPSI are based are related.     

Factor structure of the Wechsler Adult Intelligence Scale-III in schizophrenia

This report examines and compares the factor structure of the new edition of the Wechsler Adult Intelligence Scale (WAIS-III) in a sample of chronic schizophrenia and schizoaffective disorder outpatients (n = 120) and an age-matched sample of individuals drawn from the WAIS-III standardization sample (n = 200). Exploratory and confirmatory factor analyses similar to those reported by the developers of the scale suggested that a model of WAIS-III performance with correlated factors for verbal comprehension, perceptual organization, working memory, and processing speed fit the data from the schizophrenia sample as well as it fit the nonclinical comparison sample and fit the data from both samples better than alternative models.     

Relation of intelligence to ego functioning in an adult psychiatric population

Wechsler Adult Intelligence Scale-Revised (WAIS-R) IQs and clinical ratings of 10 ego functions in a diagnostically heterogeneous sample of 60 adult psychiatric inpatients were correlated. With severity of pathology statistically controlled, higher intelligence was associated with more adequate ego functioning in several spheres: primary autonomous functions, thought processes, object relations, and mastery-competence. There were also some clinically meaningful differences between the Verbal and Performance IQs in the pattern of correlations. Extending Hartmann's original views, the authors employ an ethological framework to conceptualize intelligence in relation to the ego's role in adaptation, emphasizing that intelligence is an important-albeit neglected-aspect of ego functioning.     

A longitudinal study of the performance of hypertensive and normotensive subjects on the Wechsler Adult Intelligence Scale

Performance on the Wechsler Adult Intelligence Scale was followed over two 5- to 6-year intervals for essential hypertensive Ss (EH; n = 22) free from medical complications and for normotensive Ss (N; n = 20). EH were treated with adrenergic beta-blocking drugs, diuretics, or both. Mean age was 46 years (SD = 12.6 years), initially (Time 1). Results were unaltered by adjustment for initial age. N improved modestly on the Verbal scale, from Time 1 to Time 2 only. EH neither improved nor declined on the Verbal scale. Scores remained unchanged for both EH and N Ss for the Performance scale. Overall, and at Times 2 and 3, Verbal scores were lower for the EH group. It was concluded that neither decline nor improvement in cognitive function over time are necessary outcomes of modest, carefully treated, uncomplicated hypertension in the middle years.     

Analysis of Group Rorschachs of Psychologists and Anthropologists

Wechsler Adult Intelligence Scale-Revised (WAIS-R) IQs and clinical ratings of 10 ego functions in a diagnostically heterogeneous sample of 60 adult psychiatric inpatients were correlated. With severity of pathology statistically controlled, higher intelligence was associated with more adequate ego functioning in several spheres: primary autonomous functions, thought processes, object relations, and masterycompetence. There were also some clinically meaningful differences between the Verbal and Performance IQs in the pattern of correlations. Extending Hartmann's original views, the authors employ an ethological framework to conceptualize intelligence in relation to the ego's role in adaptation, emphasizing that intelligence is an important — albeit neglected — aspect of ego functioning.