Wechsler Adult Intelligence Scale-Fourth Edition Research Articles

Apparently Abnormal Wechsler Memory Scale Index Score Patterns in the Normal Population

Interpretation of the Wechsler Memory Scale-Fourth Edition may involve examination of multiple memory index score contrasts and similar comparisons with Wechsler Adult Intelligence Scale-Fourth Edition ability indexes. Standardization sample data suggest that 15-point differences between any specific pair of index scores are relatively uncommon in normal individuals, but these base rates refer to a comparison between a single pair of indexes rather than multiple simultaneous comparisons among indexes. This study provides normative data for the occurrence of multiple index score differences calculated by using Monte Carlo simulations and validated against standardization data. Differences of 15 points between any two memory indexes or between memory and ability indexes occurred in 60% and 48% of the normative sample, respectively. Wechsler index score discrepancies are normally common and therefore not clinically meaningful when numerous such comparisons are made. Explicit prior interpretive hypotheses are necessary to reduce the number of index comparisons and associated false-positive conclusions. Monte Carlo simulation accurately predicts these false-positive rates.

Assessing Effort: Differentiating Performance and Symptom Validity

The current study aimed to clarify the relationship among the constructs involved in neuropsychological assessment, including cognitive performance, symptom self-report, performance validity, and symptom validity. Participants consisted of 120 consecutively evaluated individuals from a veteran’s hospital with mixed referral sources. Measures included the Wechsler Adult Intelligence Scale-Fourth Edition Full Scale IQ (WAIS-IV FSIQ), California Verbal Learning Test-Second Edition (CVLT-II), Trail Making Test Part B (TMT-B), Test of Memory Malingering (TOMM), Medical Symptom Validity Test (MSVT), WAIS-IV Reliable Digit Span (RDS), Post-traumatic Check List-Military Version (PCL-M), MMPI-2 F scale, MMPI-2 Symptom Validity Scale (FBS), MMPI-2 Response Bias Scale (RBS), and the Postconcussive Symptom Questionnaire (PCSQ). Six different models were tested using confirmatory factor analysis (CFA) to determine the factor model describing the relationships between cognitive performance, symptom self-report, performance validity, and symptom validity. The strongest and most parsimonious model was a three-factor model in which cognitive performance, performance validity, and self-reported symptoms (including both standard and symptom validity measures) were separate factors. The findings suggest failure in one validity domain does not necessarily invalidate the other domain. Thus, performance validity and symptom validity should be evaluated separately.

Cold Pressor-Induced Pain Does Not Impair WAIS-IV Processing Speed Index or Working Memory Index Performance

Chronic pain frequently involves cognitive complaints such as concentration and memory deficits, but studies of the effects of pain on cognition have not consistently demonstrated deficits and have not typically utilized standard neuropsychological instruments. Effects of cold pressor-induced pain on Wechsler Adult Intelligence Scale-Fourth Edition Processing Speed Index (PSI) and Working Memory Index (WMI) performance was examined in nonclinical volunteers (n = 40). All took one PSI subtest and one WMI subtest normally, and then took different PSI and WMI subtests during cold pressor-induced pain or painless warm-water immersion. Scaled scores for normal administration versus pain or painless water immersion did not differ and there was no interaction between group (control vs. pain) and manner of administration, despite moderately severe mean pain ratings (M = 6.8 on a 0–10 pain-rating scale). Results indicate that induced pain in nonclinical volunteers does not impair PSI or WMI performance, and they suggest that chronic pain per se should not be expected to substantially affect these cognitive functions. However, patients with chronic pain may differ from nonclinical volunteers in their experience of pain, potentially limiting generalizability.

Structural and incremental validity of the Wechsler Adult Intelligence Scale–Fourth Edition with a clinical sample.

Structural and incremental validity of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV; Wechsler, 2008a) was examined with a sample of 300 individuals referred for evaluation at a university-based clinic. Confirmatory factor analysis indicated that the WAIS-IV structure was best represented by 4 first-order factors as well as a general intelligence factor in a direct hierarchical model. The general intelligence factor accounted for the most common and total variance among the subtests. Incremental validity analyses indicated that the Full Scale IQ (FSIQ) generally accounted for medium to large portions of academic achievement variance. For all measures of academic achievement, the first-order factors combined accounted for significant achievement variance beyond that accounted for by the FSIQ, but individual factor index scores contributed trivial amounts of achievement variance. Implications for interpreting WAIS-IV results are discussed.

Influence of IQ in interpreting MMSE scores in patients with multiple sclerosis

ABSTRACTThe Mini-Mental State Examination (MMSE) and Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) were administered to 46 outpatients diagnosed with multiple sclerosis (MS). MMSE total raw score was significantly and positively correlated with all WAIS-IV indexes, even when controlling for the effects of participant educational level, with the strongest relationship being with Full Scale IQ. These results suggest that clinicians consider patient intellectual functioning, in particular Full Scale IQ, when diagnosing neurocognitive impairment based on screening with the MMSE in individuals with MS.

A Validated Seven-Subtest Short Form for the WAIS-IV

This study presents a short form of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV; Wechsler, 2008) using the subtests (Block Design, Similarities, Digit Span, Arithmetic, Information, Coding, and Picture Completion) suggested by Ward (1990). These seven subtests were used to predict the full WAIS-IV Full-Scale IQ, as well as the Verbal Comprehension, Perceptual Reasoning, Working Memory, and Processing Speed Index scores. Two different data sets were used: the first consisted of 70 subjects and the second consisted of 32 subjects. The first data set was used to create a linear regression and the second data set was used to validate the results and compare to the prorated score method from the WAIS-IV manual. The prorated estimated scores correlated significantly with their counterparts and proved to be a better method of estimating the Full-Scale IQ and most of the index scores, but the regression equation was better at predicting the Processing Speed Index. The current study is consistent with the Ward (1990) and Pilgrim, Meyers, Bayless, & Whetstone (1999) studies and represents a reliable and valid way of assessing intellectual functioning in an abbreviated format.

Matters of Consequence: An Empirical Investigation of the WAIS-III and WAIS-IV and Implications for Addressing the Atkins Intelligence Criterion

“Which test provides the better measurement of intelligence, the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) or the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV)?” is an important question to professional psychologists; however, it has become a critical issue in Atkins cases wherein courts are often presented with divergent Full-Scale IQ (FSIQ) scores on the WAIS-III and WAIS-IV. In these instances, courts are required to render a decision stating which test provided the better measure of an inmate's intellectual functioning. This study employed structural equation modeling to empirically determine which instrument; the WAIS-III or the WAIS-IV, provides the better measure of intelligence via the FSIQ score. Consistent with the publisher's representation of intellectual functioning, the results from this study indicate the WAIS-IV provides superior measurement, scoring, and structural models to measure FSIQ when compared to the WAIS-III.

WAIS-IV Digit Span Variables: Are They Valuable for Use in Predicting TOMM and MSVT Failure?

The Digit Span (DS) task in the Wechsler Adult Intelligence Scale-Fourth Edition differs substantially from earlier versions of the measure, with one of the major changes being the addition of a sequencing component. In the present investigation, the usefulness of the new sequencing task and other DS variables (i.e., DS Age-Scaled Score, DS Forward Total, DS Backward Total, and Reliable DS) was investigated with regard to the ability of these variables to predict negative response bias. Negative response bias was first defined and examined using below-cutoff performance on the Test of Memory Malingering (TOMM) (N = 99). Then, for comparison purposes, negative response bias was examined using below-cutoff performance on the Medical Symptom Validity Test (MSVT; N = 95). Study participants included primarily middle-aged outpatients at a Veterans Affairs medical center. Findings from this retrospective analysis showed that, regardless of whether the TOMM or the MSVT was used as the negative response bias criterion, of all the DS variables examined, DS Sequencing Total showed the best classification accuracy. Yet, due to its relatively low positive and negative predictive power, DS Sequencing Total is not recommended for use in isolation to identify negative response bias.

Structural Validity of the Dutch-Language Version of the WAIS-III in a Psychiatric Sample

The Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV; Wechsler, 2008) no longer provides the “traditional” Verbal IQ and Performance IQ deviation scores. In the current study, we investigated the structural validity of these scores in the scale's predecessor, the WAIS-Third Edition (WAIS-III; Wechsler, 1997c), which is still widely used in clinical practice, especially outside the United States. Confirmative (CFA) and exploratory factor analyses (EFA) were performed on WAIS-III data from a Dutch sample of 247 psychiatric patients. Four competing models were tested in the CFA on 11 subtests. The model that fit the data best was a model in which subtests loaded on the four factor indexes (i.e., 3 Verbal Comprehension subtests, 3 Perceptual Organization subtests, 3 Working Memory subtests, and 2 Processing Speed subtests) as proposed by the manual (Wechsler, 1997b). In the EFA on 13 subtests with four factors extracted, all subtests were found to load on the factors in accordance with the WAIS-III test manual. However, Picture Arrangement, Arithmetic, and Picture Completion showed only moderate loadings on the proposed factors. Implications for clinical practice are discussed.

An Exploratory Study of the Use of the Wechsler Digit–Symbol Incidental Learning Procedure with the WAIS-IV

The Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) does not include the optional Incidental Learning procedure for the Digit–Symbol subtest (now simply called Coding) that had been available in the WAIS-Third Edition (WAIS-III). However, the procedure itself has been shown to have some utility in assessment of incidental memory processes. The current study of a mixed clinical outpatient sample (n = 75) sought to identify salient characteristics of the Incidental Learning tasks as applied to WAIS-IV Coding. Findings showed that the Pairing procedure, when applied to the WAIS-IV, has different characteristics than it did with the WAIS-III; it is more difficult overall, and different items tend to be more prominently recalled than others. The Free Recall procedure for the WAIS-IV is comparable to the WAIS-III version in overall difficulty. Implications and implementation of the current findings are discussed.

WAIS-IV subtest covariance structure: Conceptual and statistical considerations.

D. Wechsler (2008b) reported confirmatory factor analyses (CFAs) with standardization data (ages 16-69 years) for 10 core and 5 supplemental subtests from the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV). Analyses of the 15 subtests supported 4 hypothesized oblique factors (Verbal Comprehension, Working Memory, Perceptual Reasoning, and Processing Speed) but also revealed unexplained covariance between Block Design and Visual Puzzles (Perceptual Reasoning subtests). That covariance was not included in the final models. Instead, a path was added from Working Memory to Figure Weights (Perceptual Reasoning subtest) to improve fit and achieve a desired factor pattern. The present research with the same data (N = 1,800) showed that the path from Working Memory to Figure Weights increases the association between Working Memory and Matrix Reasoning. Specifying both paths improves model fit and largely eliminates unexplained covariance between Block Design and Visual Puzzles but with the undesirable consequence that Figure Weights and Matrix Reasoning are equally determined by Perceptual Reasoning and Working Memory. An alternative 4-factor model was proposed that explained theory-implied covariance between Block Design and Visual Puzzles and between Arithmetic and Figure Weights while maintaining compatibility with WAIS-IV Index structure. The proposed model compared favorably with a 5-factor model based on Cattell-Horn-Carroll theory. The present findings emphasize that covariance model comparisons should involve considerations of conceptual coherence and theoretical adherence in addition to statistical fit.

Estimating WAIS‐IV Indexes: Proration Versus Linear Scaling in a Clinical Sample

We compared the accuracy of proration and linear scaling for estimating Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV), Verbal Comprehension Index (VCI), and Perceptual Reasoning Index (PRI) composites from all possible two subtest combinations. The purpose was to provide practice relevant psychometric results in a clinical sample. The present investigation was an archival study that used mostly within-group comparisons. We analyzed WAIS-IV data of a clinical sample comprising 104 patients with brain damage and 37 with no known neurological impairment. In both clinical samples, actual VCI and PRI scores were highly correlated with estimated index scores based on proration and linear scaling (all rs ≥.95). In the brain-impaired sample, significant mean score differences between the actual and estimated composites were found in two comparisons, but these differences were less than three points; no other significant differences emerged. Overall, findings demonstrate that proration and linear scaling methods are feasible procedures when estimating actual Indexes. There was no advantage of one computational method over the other.

Effects of Practice on the Wechsler Adult Intelligence Scale-IV Across 3- and 6-Month Intervals

A total of 54 participants (age M = 20.9; education M = 14.9; initial Full Scale IQ M = 111.6) were administered the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) at baseline and again either 3 or 6 months later. Scores on the Full Scale IQ, Verbal Comprehension, Working Memory, Perceptual Reasoning, Processing Speed, and General Ability Indices improved approximately 7, 5, 4, 5, 9, and 6 points, respectively, and increases were similar regardless of whether the re-examination occurred over 3- or 6-month intervals. Reliable change indices (RCI) were computed using the simple difference and bivariate regression methods, providing estimated base rates of change across time. The regression method provided more accurate estimates of reliable change than did the simple difference between baseline and follow-up scores. These findings suggest that prior exposure to the WAIS-IV results in significant score increments. These gains reflect practice effects instead of genuine intellectual changes, which may lead to errors in clinical judgment.

Some supplementary methods for the analysis of WAIS‐IV index scores in neuropsychological assessment

To develop supplementary methods for the analysis of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) in neuropsychological assessment. Psychometric. The following methods are made available: (a) provision of traditional confidence intervals (CIs) on index scores, (b) expression of the endpoints of CIs as percentile ranks; (c) quantification of the number of abnormally low index scores exhibited by a case and accompanying estimate of the percentage of the normative population expected to exhibit at least this number of low scores; (d) quantification of the reliability and abnormality of index score deviations from an individual's index score mean (thereby offering an alternative to the pairwise approach to index score comparisons available in the WAIS-IV manual); (e) provision of CIs on an individual's deviation scores or pairwise difference scores, (f) estimation of the percentage of the normative population expected to exhibit at least as many abnormal deviations or abnormal pairwise differences as a case; and (g) calculation of a case's Mahalanobis distance index (MDI), thereby providing a multivariate estimate of the overall abnormality of an index score profile. With the exception of the MDI, all the methods can be applied using tables provided in this paper. However, for ease and speed of application, and to reduce the possibility of clerical error, all the methods have also been implemented in a computer program. The methods are useful for neuropsychological interpretation of the WAIS-IV.

Confirmatory Factor Analysis of the WAIS-IV/WMS-IV

The Wechsler Adult Intelligence Scale-fourth edition (WAIS-IV) and the Wechsler Memory Scale-fourth edition (WMS-IV) were co-developed to be used individually or as a combined battery of tests. The independent factor structure of each of the tests has been identified; however, the combined factor structure has yet to be determined. Confirmatory factor analysis was applied to the WAIS-IV/WMS-IV Adult battery (i.e., age 16-69 years) co-norming sample (n = 900) to test 13 measurement models. The results indicated that two models fit the data equally well. One model is a seven-factor solution without a hierarchical general ability factor: Verbal Comprehension, Perceptual Reasoning, Processing Speed, Auditory Working Memory, Visual Working Memory, Auditory Memory, and Visual Memory. The second model is a five-factor model composed of Verbal Comprehension, Perceptual Reasoning, Processing Speed, Working Memory, and Memory with a hierarchical general ability factor. Interpretative implications for each model are discussed.

The Utility of the Post-concussive Symptom Questionnaire

The Post-concussive Symptom Questionnaire (PCSQ) and its short forms were evaluated to determine their utility in measuring symptom validity as brief self-report measures in 112 individuals referred for a neuropsychological evaluation. First, the relationships between the PCSQ forms and measures of cognitive performance (Wechsler Adult Intelligence Scale-Fourth Edition Full-Scale IQ, California Verbal Learning Test-Second Edition Trials 1-5 Total T-score, Trails B, FAS), general distress (Minnesota Multiphasic Personality Inventory [MMPI]-2 M8), and self-report symptom validity (MMPI-2 FBS Symptom Validity Scale [FBS] and Response Bias Scale [RBS]) were investigated to determine construct validity. Measures of self-report symptom validity explained the greatest amount of variance. Second, receiver operating characteristics curve analyses were conducted to determine the predictive value of the PCSQ forms in detecting over reporting on the FBS and the RBS in addition to establishing optimal cutoff scores. On the basis of the proposed cutoff scores, sensitivity, specificity, positive predictive power, negative predictive power, and hit rates were calculated.

Independent examination of the Wechsler Adult Intelligence Scale—Fourth Edition (WAIS-IV): What does the WAIS-IV measure?

Published empirical evidence for the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) does not address some essential questions pertaining to the applied practice of intellectual assessment. In this study, the structure and cross-age invariance of the latest WAIS-IV revision were examined to (a) elucidate the nature of the constructs measured and (b) determine whether the same constructs are measured across ages. Results suggest that a Cattell-Horn-Carroll (CHC)-inspired structure provides a better description of test performance than the published scoring structure does. Broad CHC abilities measured by the WAIS-IV include crystallized ability (Gc), fluid reasoning (Gf), visual processing (Gv), short-term memory (Gsm), and processing speed (Gs), although some of these abilities are measured more comprehensively than are others. Additionally, the WAIS-IV provides a measure of quantitative reasoning (QR). Results also suggest a lack of cross-age invariance resulting from age-related differences in factor loadings. Formulas for calculating CHC indexes and suggestions for interpretation are provided.