Abnormal and reliable differences among Wechsler Memory Scale—Revised subtests.

Abstract

Standardization data for the Wechsler Memory Scale-Revised (WMS-R) were used to generate confidence intervals for the statistical abnormality of differences between scales. Tables are provided for evaluation of material-specific rates of forgetting on the Logical Memory and Visual Reproduction subtests, adequacy of overall retention as reflected by contrasts between the General and Delayed Memory Indexes, and test-retest changes on the WMS-R scales. Confidence intervals derived from reliability and abnormality data are compared. The clinical significance of a discrepancy between scales may be better addressed by reference to information about the latter probability.The Wechsler Memory Scale (Wechsler, 1945) provided a single summary score or Memory Quotient that consolidated measures of attention, verbal, and nonverbal recall, but did not differentiate various aspects of memory. The Wechsler Memory Scale-Revised (WMS-R) was improved by the inclusion of separate indexes summarizing Visual Memory, Verbal Memory, General Memory, Attention/Concentration, and 30-min Delayed Recall tasks (Wechsler, 1987).Comparisons between the patient's scores on these scales may provide useful diagnostic information. For example, Butters et al. (1988) and Wechsler (1987) reported that scores on the Attention/Concentration Index were significantly higher than were General and Delayed Memory Index scores in Alzheimer's and amnesic patients. A similar pattern characterized the residual memory deficits of patients who had sustained moderate to severe closed head injuries (Crossen & Wiens, 1988;Wechsler, 1987). The Delayed Memory Index was significantly lower than was the General Memory Index in amnesia and closed head injury patients (Butters et al., 1988;Crossen & Wiens, 1988;Wechsler, 1987), indicating an abnormal rate of forgetting in these conditions.Contrasts between the immediate and delayed recall trials on the Logical Memory and Visual Reproduction subtests may also provide useful clinical information. Consistent with studies using the earlier versions of these subtests (Russell, 1988), when delayed and immediate recall conditions are compared, it has been found that patients with disease processes such as Alzheimer's dementia, alcoholic Korsakoff's syndrome, and Huntington's disease retain less information than normal after 30 min (Butters et al., 1988). Differential rates of forgetting may

Performance discrepancies between the Children's Category Test (CCT) and the California Verbal Learning Test–Children's (CVLT–C) Version in the standardization sample

“…Therefore, statistically significant differences between these scores are not necessarily clinically significant. This finding is consistent with those reported in investigations of the standardization samples of other instruments such as the WAIS-R (Matarazzo & Herman, 1984), the WISC-III (Wechsler, 1991), the WIAT (Wechsler, 1992), and the WMS-R (Mittenberg et al, 1991). The current results also indicate that the CCT and CVLT-C measure fairly different aspects of a child's learning ability.…”

Performance discrepancies on the California Verbal Learning Test–Children's Version in the standardization sample

“…Multiplying this statistic by an appropriate factor yields the amount of the difference that is statistically significant at any given level of confidence. Because of the absence of information about the reliability of some of the scores, the simple difference method was used for this purpose (Mittenberg et al, 1991;Reynolds, 1984). The associated formula is as follows: D 5 Z 3 SD 3 #~2 2 2r xy ), where D is the difference score, Z is the normal curve value associated with the desired level of statistical significance (i.e., 1.28 for an alpha of .10, 1.65 for an alpha of .05, and 2.33 for an alpha of .01), SD is the standard deviation of the scales being compared (i.e., 1 in these cases), and r xy is the correlation between the scales.…”

Individual patient prediction of seizure lateralization in temporal lobe epilepsy: A comparison between neuropsychological memory measures and the Intracarotid Amobarbital Procedure

“…In the clinical analysis, we considered that in order to confidently conclude the presence of a material-specific memory deficit in any given patient, the disparity between his or her material-specific memory scores had to be significantly greater than the disparity that is observed in the majority of the normal population. Therefore, on the WMS-R, a disparity of greater than or equal to 29 points between the Verbal and Visual Memory Indexes, which occurs in less than 5% of the normal population (Mittenberg et al, 1991), was selected as an appropriate cutoff to conclude the presence of a materialspecific memory deficit. 1 For the WRMT, a similarly derived cutoff of greater than or equal to 7 scaled score points difference between memory for Words and Faces was used to conclude the presence of a material-specific memory deficit.…”