Test-retest reliability and practice effects of the Wechsler Memory Scale-III

Although serial administration of cognitive tests is increasingly common, there is a paucity of research on test-retest reliabilities and practice effects, both of which are important for evaluating changes in functioning. Reliability is generally conceptualized as involving short-lasting changes in performance. However, when repeated testing occurs over a period of years, there will be some longer lasting effects. The implications of these longer lasting effects and practice effects on reliability were examined in the context of repeated administrations of the Wechsler Memory Scale-III in 339 community-dwelling women aged 40-79 years over 2 to 7 years. The results showed that Logical Memory and Verbal Paired Associates subtests were consistently the most reliable subtests across the age cohorts. The magnitude of practice effects varied as a function of subtests and age. The largest practice effects were found in the youngest age cohort, especially on the Faces, Logical Memory, and Verbal Paired Associates subtests.     

Dyadic short forms of the Wechsler Adult Intelligence Scale-III

Various short forms of the Wechsler Adult Intelligence Scale (WAIS)/WAIS-R have been developed to obtain estimates of overall intellectual level, although little research of WAIS-III short forms has been published to date. Full Scale IQ (FSIQ) estimatesfromfour WAIS-III dyadic short forms were obtained by entering selected subtest scores from a mixed neurologic/ psychiatric sample (n = 196) into regression equations. Results were cross validated on a second sample (n = 57). Within both samples, WAIS-III FSIQ scores were highly correlated (r = .90-.92, p < .001) with estimated FSIQ scores. Estimated FSIQ fell within 5 points of actual FSIQ in 49% to 74% of cross-validation cases and within 10 points of actual FSIQ in 81% to 93% of the sample. Comparable to findings from previous short-form investigations, actual and estimated FSIQ classification levels agreed in 46% to 67% of cases in the cross-validation sample. These dyadic WAIS-III forms appear appropriate for obtaining gross estimates of FSIQ in similar populations, although caution is recommended in interpreting estimated IQ scores.     

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.     

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.     

Wechsler Digit Span subtest: diagnostic usefulness with dyslexic children

The current study supports Levinson's contention (1988) that the diagnosis of dyslexia cannot be based solely on neurophysiological evidence but must be made in conjunction with reading and educational test scores. Contrary to much current research, in the present study specific WISC-R profiles are identified within a stringently defined subgroup of 57 9- to 12-yr-old dyslexic children. Well-defined subtest scatter can differentiate dyslexics from proficient readers. In particular, the Digit Span subtest, which is not routinely administered by psychologists or included in computing Verbal IQ, can be considered an important component of a diagnostic battery. Unexpectedly, Coding emerged with Digit Span as a third factor in a principal component analysis; statistically significant sex differences appeared on the Coding task. Findings appear to confirm the phonological encoding deficiencies displayed by dyslexics on the Digit Span subtest. This study strongly supports consideration of WISC-R subtest differences, along with correlated factors, neurophysiological and perceptual evidence, when diagnosing dyslexic children. Cross-validation is planned.     

Ego development and intelligence in a psychiatric population: Wechsler subtest scores

The relationship between Loevinger's measure of ego development and the Wechsler Intelligence Scales subtest scores was investigated in 91 adolescent and young adult psychiatric inpatients. Correlations with Verbal IQ and verbal subtests in general were positive and significant. The correlation with the Comprehension subtest was the highest and remained significant when Full Scale IQ was partialled. Post-conformists obtained the highest mean scores on Picture Arrangement; however, there was no difference among the lower stages on this subtest. The results lend support to a social reasoning component of ego development.     

Parsimonious prediction of Wechsler Memory Scale--III memory indices

Equations for prorating the Wechsler Memory Scale--III (WMS-III) Index scores were derived and validated on a sample of 252 mixed clinical cases. Regression equations were performed using age-scaled scores as predictors and the sum of age-scaled scores for Immediate Memory (IM) and General Memory (GM) as the criteria. Including Logical Memory and Verbal Paired Associates with either Faces or Family Pictures resulted in estimated scores that accounted for 95% to 97% of the variance for IM and GM. Over 80% of these cases had estimated sum of scaled scores that fell within 3 points of actual sum of scaled scores, within 1 standard error of measurement. When only Logical Memory and Verbal Paired Associates were included, estimations accounted for only 87% of the variance, and only 60% of the estimated scores fell within 3 points of actual sum of scaled scores. The regression equations are presented, as are the confidence intervals derived from a bootstrapping procedure that created 15,000 different samples.     

A revalidation of the Thurstone Test of Mental Alertness as a brief measure of intelligence through comparison with the Wechsler Adult Intelligence Scale-III

In earlier research, Rossini, Wygonik, Barrett, and Friedman (1994) demonstrated that the Thurstone Test of Mental Alertness (TMA) is a valid, brief measure of intelligence by comparing it to the Wechsler Scale of Adult Intelligence-Revised, which was at that time the "gold standard" of IQ assessment. Since that study, the WAIS has again been revised and reissued in a third edition, the WAIS-III. We assessed the relationship between scores on the Thurstone Test of Mental Alertness and this latest WAIS test to see if there is still a predictive relationship between the two tests. Correlations between the two tests and the accuracy of TMA point estimates of IQ indicate that the Thurstone Test of Mental Alertness remains a viable brief measure of adult intelligence.     

Memory for Faces in Children with Autism

Previous research has established that children with Autistic Disorder have deficits in aspects of social cognition and in verbal memory, but research on social memory is limited. Twenty-four autistic boys aged 7 to 12 years and normal controls matched for verbal mental age were administered parallel social and nonsocial matching and memory tasks. Results showed that the children with autism were impaired relative to the normal children on the social (face) memory task only. Furthermore, of the four experimental tasks, the social memory task had the highest and most consistent correlations with measures of social development and adaptive skills. Whereas the normal children used the special status of faces to recall them more easily than objects, the children with autism showed equal recall of objects and faces.     

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).     

Parallel-form reliability of the Wechsler Memory Scale in a geriatric population with suspected dementia

The present study examined parallel-form reliability of the Wechsler Memory Scale (WMS) in a population where such forms are particularly useful, that is, among patients who are suspected of having some type of dementing illness. Comparative analyses were made for total raw scores. Memory Quotient (MQ) scores, and individual subtest scores. Thirty geriatric patients originally referred for neuropsychological testing because of suspected dementia were given both Forms 1 and 2 of the WMS. The results yielded high overall reliability coefficients for MQ and total raw scores. Individual subtest scores also yielded rather high coefficients, and only one subtest (Associate Learning) had a significant mean difference. Apparently, the two forms have sufficient parallel-form reliability to be considered clinically interchangeable. Thus, the WMS may be a useful tool for repeat evaluations of memory functioning in a demented population.     

Memory for Objects and Faces by the Mentally Retarded and Nonretarded

Visual recognition skills of 26 mentally retarded high school students were compared with the skills of two groups of nonretarded students. All groups were taught to recognize 32 target faces and objects and were retested 1 week, 1 month, and 2 months later. The counterintuitive findings were that there were no significant differences between the retarded and nonretarded groups in memory for faces on any of the retest trials. All groups remembered faces significantly better than they did objects and remembered more of the pictures at 1 week than they did at 1 month or at 2 months. There was no significant loss over time in memory for faces. Relative to nonretarded subjects, the retarded subjects exhibited deficits in encoding and remembering objects but showed no such deficits in encoding and remembering faces. The results suggest that different configurational features may be used to encode objects as opposed to faces.     

Memory in traumatic brain injury: The effects of injury severity and effort on the Wechsler Memory Scale‐III

This study examined the effects of traumatic brain injury (TBI) on Wechsler Memory Scale‐III (WMS‐III) performance. Since poor effort potentially contaminates results, effort was explicitly assessed and controlled using two well‐validated cognitive validity indicators, the Portland Digit Recognition Test (PDRT) and Reliable Digit Span (RDS). Participants were 44 mild TBI patients with good effort, 48 mild TBI patients with poor effort, and 40 moderate–severe TBI patients with good effort. A dose–response relationship between injury severity and WMS‐III performance was demonstrated. Effect size calculations showed that the good effort mild TBI patients did not differ from normal (average Cohen's d= 0.07) while moderate–severe TBI had a moderate effect on WMS‐III scores (average Cohen's d=?0.52). Consistent with previous literature, the moderate–severe TBI group scored the lowest on WMS‐III Visual indices. Effort had a larger effect than injury severity on WMS‐III scores (average Cohen's d=?1.27). Clinical implications of these findings are discussed.