Age-related invariance of abilities measured with the Wechsler Adult Intelligence Scale-III.

Examination of measurement invariance tests the assumption that the model underlying a set of test scores is directly comparable across groups. The observation of measurement invariance provides fundamental evidence for the inference that scores on a test afford equivalent measurement of the same psychological traits among diverse groups. Groups may be derived from different psychosocial backgrounds or different clinical presentations. In the Wechsler Adult Intelligence Scale-III (WAIS-III)/Wechsler Memory Scale-III (WMS-III) Technical Manual (Psychological Corporation, 2002), there appears to be a breakdown in factor structure among the standardization cases in older adults. In this study, the authors evaluated the invariance of the measurement model of the WAIS-III across 5 age bands. All components of the measurement model were examined. Overall, the evidence pointed to invariance across age of a modified 4-factor model that included cross-loadings for the Similarities and Arithmetic subtests. These results support the utility of the WAIS-III as a measure of stable intelligence traits across a wide age range. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Education-Stratified Base-Rate Information on Discrepancy Scores Within and Between the Wechsler Adult Intelligence Scale-Third Edition and the Wechsler Memory Scale-Third Edition.

The Wechsler Adult Intelligence Scale--Third Edition (WAIS-III; D. Wechsler, 1997a) and the Wechsler Memory Scale--Third Edition (WMS-III; D. Wechsler, 1997b) are 2 of the most frequently used measures in psychology and neuropsychology. To facilitate the diagnostic use of these measures in the clinical decision-making process, this article provides information on education-stratified, directional prevalence rates (i.e., base rates) of discrepancy scores between the major index scores for the WAIS-III, the WMS-III, and between the WAIS-III and WMS-III. To illustrate how such base-rate data can be clinically used, this article reviews the relative risk (i.e., odds ratio) of empirically defined "rare" cognitive deficits in 2 of the clinical samples presented in the WAIS-III--WMS-III Technical Manual (The Psychological Corporation, 1997). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relationship between institutionalization, other demographic variables, and the structure of intelligence in chronic schizophrenics.

A factor analytic investigation was carried out studying the relationship between length of institutionalization and several other premorbid-demographic variables and the structure of the Wechsler Adult Intelligence Scale (WAIS) in a sample of chronic schizophrenics. Only 3 of these background variables were related to WAIS subtests. 2, education and aging, differentiated within this sample the same way as in the general population: i.e., education was associated with generally higher performance on all subtests while aging was selectively related to lowered psychomotor and memory/attentional functioning. The 3rd, length of institutionalization, showed negative relationship with Comprehension score, suggesting some impairment in social judgment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of demographic norms for four new WAIS-III/WMS-III indexes.

Following the publication of the third edition Wechsler scales (i.e., WAIS-III and WMS-III), demographically corrected norms were made available in the form of a computerized scoring program (i.e., WAIS-III/WMS-III/WIAT-II Scoring Assistant). These norms correct for age, gender, ethnicity, and education. Since then, four new indexes have been developed: the WAIS-III General Ability Index, the WMS-III Delayed Memory Index, and the two alternate Immediate and Delayed Memory Indexes. The purpose of this study was to develop demographically corrected norms for the four new indexes using the standardization sample and education oversample from the WAIS-III and WMS-III. These norms were developed using the same methodology as the demographically corrected norms made available in the WAIS-III/WMS-III/WIAT-II Scoring Assistant. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

General Ability Index for the WAIS-III: Canadian Norms.

The Wechsler Adult Intelligence Scale-Third Edition (WAIS-III; Wechsler, 1997) permits the calculation of both traditional IQ and Index scores. The Verbal Comprehension and Perceptual Organization indexes are the most highly "g" loaded compared to the Working Memory and Processing Speed indexes that may be more sensitive to some neuro-cognitive disorders. In certain clinical situations, a general ability composite score based on the combination of only the verbal and performance indexes is desirable. Following the procedure for calculating a General Ability Index (GAI; Prifitera, Weiss, & Saklofske, 1998) for the Wechsler Intelligence Scale for Children-Third Edition (WISC-HI; Wechsler, 1991) and the WAIS-III (Tulsky, Saklofske, Wilkins, & Weiss, 2001), GAI normative tables for the WAIS-III Canadian standardization sample are reported here to complement earlier published GAI Canadian norms tables for the WISC-III. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of a General Ability Index for the Wechsler Adult Intelligence Scale—Third Edition.

The Wechsler Adult Intelligence Scale-Third Edition (WAIS-III; D. Wechsler, 1997) permits the calculation of both traditional IQ and index scores. However, if only the subtests constituting the index scores are administered, especially those yielding the Verbal Comprehension and Perceptual Organization Indexes, there is no equivalent measure of Full Scale IQ. Following the procedure for calculating a General Ability Index (GAI; A. Prifitera, L. G. Weiss, & D. H. Saklofske, 1998) for the Wechsler Intelligence Scale for Children - IIIrd Edition (WISC--III) (D. Wechsler, 1991), GAI normative tables for the WAIS-III standardization sample are reported here. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Confirmatory factor analysis of the Wechsler Intelligence Scale for Children-Third Edition in an Australian clinical sample.

A confirmatory factor analysis was conducted on the Wechsler Intelligence Scale for Children-Third Edition (WISC-III; D. Wechsler, 1991) with a sample of 579 Australian children referred for assessment because of academic difficulties in the classroom. The children were administered the WISC-III as part of the initial eligibility determination process for funding of special education services. The children were aged between 6 years and 16 years 7 months. One-, two-, three-, and four-factor models were tested. The four-factor model proposed in the WISC-III manual fit the data significantly better than all other models tested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Confirmatory Analysis of the Factor Structure and Cross-Age Invariance of the Wechsler Adult Intelligence Scale-Third Edition.

In the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III; D. Wechsler, 1997), the manual reports several confirmatory factor analyses in support of the instrument's latent factor structure. In practice, examiners frequently compare an examinee's score from a current administration of the WAIS-III with the results from a previous test administration. Implicit in test-retest score comparisons is evidence that scores retain similar interpretive meaning across time. Establishing an instrument's factorial invariance provides the foundation for this practice. This study investigated the factorial invariance of the WAIS-III across the instrument's 13 age groups. The overall results from this study generally support both configural and factorial invariance of the WAIS-III when the 11 primary tests are administered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Orthogonal higher order structure and confirmatory factor analysis of the French Wechsler Adult Intelligence Scale (WAIS-III).

According to the most widely accepted Cattell–Horn–Carroll (CHC) model of intelligence measurement, each subtest score of the Wechsler Intelligence Scale for Adults (3rd ed.; WAIS–III) should reflect both 1st- and 2nd-order factors (i.e., 4 or 5 broad abilities and 1 general factor). To disentangle the contribution of each factor, we applied a Schmid–Leiman orthogonalization transformation (SLT) to the standardization data published in the French technical manual for the WAIS–III. Results showed that the general factor accounted for 63% of the common variance and that the specific contributions of the 1st-order factors were weak (4.7%–15.9%). We also addressed this issue by using confirmatory factor analysis. Results indicated that the bifactor model (with 1st-order group and general factors) better fit the data than did the traditional higher order structure. Models based on the CHC framework were also tested. Results indicated that a higher order CHC model showed a better fit than did the classical 4-factor model; however, the WAIS bifactor structure was the most adequate. We recommend that users do not discount the Full Scale IQ when interpreting the index scores of the WAIS–III because the general factor accounts for the bulk of the common variance in the French WAIS–III. The 4 index scores cannot be considered to reflect only broad ability because they include a strong contribution of the general factor. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The structure of intelligence in children and adults with high functioning autism.

Confirmatory factor analyses of the commonly used 11 subtests of the Wechsler child and adult intelligence scales were accomplished for 137 children and 117 adults with high functioning autism (HFA) and for comparable age groups from the standardization samples contained in the Wechsler manuals. The objectives were to determine whether the structure of intelligence in HFA groups was similar to that found in the normative samples, and whether a separate "social context" factor would emerge that was unique to HFA. Four-factor models incorporating a Social Context factor provided the best fit in both the autism and normative samples, but the subtest intercorrelations were generally lower in the autism samples. Findings suggest similar organization of cognitive abilities in HFA, but with the possibility of underconnectivity or reduced communication among brain regions in autism. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

No, It Is Not Possible to Be Schizophrenic Yet Neuropsychologically Normal.

Cognitive impairment is well documented in schizophrenia, though some reports have been interpreted to suggest that it is possible to have schizophrenia without neuropsychological impairment. The authors tested this by comparing the neuropsychological profiles of closely matched patients with schizophrenia and healthy comparison participants. Sixty-four patients with schizophrenia and 64 healthy comparison cases, matched to within 3 Full-Scale IQ points, were tested using the Wechsler Adult Intelligence Scale (3rd ed.; D. Wechsler, 1997b) and the Wechsler Memory Scale (3rd ed.; D. Wechsler, 1997c). Neuropsychological profiles for these groups were markedly different, with the group of patients with schizophrenia exhibiting performance deficits in memory and speeded visual processing but superior verbal comprehension and perceptual organization relative to the group of healthy comparison participants matched on Full-Scale IQ. Thus, scoring in the normal range does not preclude neuropsychological abnormality in schizophrenia, confirming that neuropsychological impairment is a core feature of the illness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Construct validity of the Wechsler Abbreviated Scale of Intelligence and Wide Range Intelligence Test: Convergent and structural validity.

The Wechsler Abbreviated Scale of Intelligence (WASI; Psychological Corporation, 1999) and the Wide Range Intelligence Test (WRIT; Glutting, Adams, & Sheslow, 2000) are two well-normed brief measures of general intelligence with subtests purportedly assessing verbal–crystallized abilities and nonverbal–fluid–visual abilities. With a sample of 152 children, adolescents, and adults, the present study reports meaningful convergent validity coefficients and a latent factor structure consistent with the theoretical intellectual models both tests were constructed to reflect. Consideration of the hierarchical model of intelligence tests and issues regarding test interpretation are presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ipsative Comparisons of Index Scores for the Canadian WAIS-III.

The Canadian standardization of the Wechsler Adult Intelligence Scale--Third Edition (WAIS-III; Wechsler, 1997a, 2001) provides factor-based index scores, giving an intermediate level of analysis between IQ scores and individual subtests. This article provides tables for comparing all indices to the mean index score, and for identifying the statistical significance and relative frequency of obtained differences. This simultaneous or ipsative approach can avoid some of the statistical and logical pitfalls of multiple pairwise comparisons, such as decreased interpretability and inflated risk of Type I errors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Canadian WISC-III directional base rates of score discrepancies by ability level.

A recent advancement in the clinical interpretation of test scores from the Wechsler Intelligence Scale for Children-Third Edition (WISC-III; Wechsler, 1991) and the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III; Wechsler, 1997) is the use of antecedent probability or base rate data. However, the WISC-III only included a single table that did not reflect the direction of score differences. The Canadian standardization data for the WISC-III (The Psychological Corporation, 1996) were employed to create two-directional base rate tables based on five ability levels. These more comprehensive tables are in line with the approach frequently taken by psychologists in the interpretation of intelligence test data. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Supplementary WMS-III tables for determining primary subtest strengths and weaknesses.

It is common practice to evaluate the age-adjusted subtest scores from the Wechsler intelligence scales to determine strengths and weaknesses within a profile. The Wechsler Memory Scale-III (WMS-III; D. Wechsler, 1997a) represents a significant improvement over its predecessors and, for the first time, provides age-adjusted subtest scores for interpretation, just as the Wechsler intelligence scales have done for 60 years. It is reasonable to assume that examiners will evaluate the WMS-III subtest profiles for strengths and weaknesses. However, the WMS-III Administration and Scoring Manual and the WAIS-III—WMS-III Technical Manual (The Psychological Corporation, 1997) provide no assistance for accomplishing this goal. Data from the WMS-III standardization sample, as described in the WAIS-III-WMS-III Technical Manual, were used to develop tables for determining both confidence levels and infrequency of differences between individual subtest scores and the means of 5 subtest combinations that may be clinically relevant for individual cases. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mayo cognitive factors scales: Derivation of a short battery and norms for factor scores.

G. E. Smith et al (see PA, Vol 80:4129 and 24183) confirmed that 5 factors underlie the covariance structure of a core battery of the Wechsler Adult Intelligence Scale—Revised (WAIS—R), Wechsler Memory Scale—Revised (WMS—R), and Auditory Verbal Learning Test administered to the Mayo's Older Americans Normative Studies sample and to an independent clinical sample. In the present study, full factor scores generated by this 5-factor model were used as criterion variables in the development of a short battery. It was determined that 16 of the 24 subtests were sufficient to explain substantial variance in the 5 factor scores. However, 1 additional immediate memory subtest must be administered as a prelude to a delayed recall test. Thus, a collection of 17 subtests are offered as a short battery for older persons. Norms for the calculation of Mayo Cognitive Factor Scales scores are presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Confirmatory factor analysis of the WAIS–III standardization data.

Confirmatory factor analyses with the standardization data of the Wechsler Adult Intelligence Scale–Third Edition (Wechsler, 1997a) compared 6 models with 1 to 4 factors for 11- and 13-subtest versions of the test. Three factors usually fit the data better than 2 factors, but 2-factor models were more parsimonious. A 2-factor model with a Verbal Comprehension factor (Vocabulary, Similarities, Information, and Comprehension) was as good as and sometimes better than the 2-factor model defined by the traditional separation of Verbal and Performance subtests. For 3-factor models, alternative specifications of processing speed subtests on either the Perceptual Organization or Freedom From Distractibility factor were comparable, and specifying a 4th factor for Digit Symbol and Symbol Search had little advantage in comparison with 3-factor models with correlated errors for the 2 subtests. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Confirmatory factor analysis of the WMS-III in patients with temporal lobe epilepsy.

Five competing models specifying the factor structure underlying the Wechsler Memory Scale--Third Edition (D. Wechsler, 1997b) primary subtest scores were evaluated in a sample of patients with intractable temporal lobe epilepsy (N=254). Models specifying separate immediate and delayed constructs resulted in inadmissible parameter estimates and model specification error. There were negligible goodness-of-fit differences between a 3-factor model of working memory, auditory memory, and visual memory and a nested--more parsimonious--2-factor model of working memory and general memory. The results suggest that specifying a separate visual memory factor provides little advantage for this sample--an unexpected finding in a population with lateralized dysfunction, for which one might have predicted separate auditory and visual memory dimensions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An abbreviation of the WISC for clinical use.

The present study was designed to test a short form of the Wechsler Intelligence Scale for Children (WISC) on a sample of emotionally disturbed children. The present findings support the usefulness of the abbreviated WISC form, except for subjects in the Bright Normal and Superior Ranges of intelligence. These ranges comprise roughly 25% of the children in the normal population. Although the correlations between the two forms were impressive when analyzed on the combined sample and by age levels, the correlations (scales and subtests) did drop appreciably in the upper IQ ranges when analyzed by level of Full Scale IQ. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A confirmatory maximum likelihood factor analysis of the WAIS-R.

A simultaneous maximum likelihood confirmatory factor analysis of intercorrelations among the 11 subtests of the WAIS–R was undertaken in the 9 age groups in the normative sample (D. Wechsler, 1981). Several models were fit to the data and compared, including a single-factor model; orthogonal and oblique 2-factor models, comprised of the Verbal and Performance subtests, respectively; an orthogonal and 2 oblique 3-factor models, the 3rd factor involving the Digit Span, Arithmetic, and Digit Symbol subtests; a 3-factor model, composed of a general intellectual factor and Verbal and Performance factors; and a 4-factor model, consisting of both a general factor and 3 common ability factors (Verbal Comprehension, Perceptual Organization, and Memory/Freedom from Distractability). Results suggest that (a) the single-factor model fits the data fairly well, although there is some misspecification in this model; (b) none of the multifactor models fit the data markedly better than the single-factor model; and (c) the single-factor structure is consistent across the age groups. It is concluded that the WAIS–R largely contains a general intellectual factor and that any common ability factors therein play a minor role in influencing WAIS–R subscale scores. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)