WAIS—R Scatter with Psychiatric Inpatients: I. Intrasubtest Scatter

Abstract

Intrasubtest scatter values for eight WAIS-R subtests were estimated for a sample of 150 psychiatric inpatients and compared with those reported for a comparable portion of the WAIS-R standardization group by Kaplan, Fein, Morris, and Delis in 1991, using the normal deviate (z) test. The standardization group's intrasubtest scatter was significantly greater than those reported for the psychiatric inpatients on all subtests except Arithmetic and Information. These results suggested that, contrary to expectation, limited intrasubtest scatter may characterize WAIS-R protocols of psychiatric inpatients, while the presence of scatter may characterize normal WAIS-R performance.

WAIS-R item difficulties with psychiatric inpatients

“…Thus, a relatively consistent sequence of incorrect responses is expected, with departures from this expected sequence of successes and failures suggestive of psychopathology (Broder & Oresick, 1987;Feinberg & McIlvried, 1991; Kellerrnan & Burry, 1991; Nikols, 1963) or brain dysfunction (Kaplan, Fein, Morris, & Delis, 1991; Lezak, 1983; Mittenberg, Hammeke, & Rao, 1989; Mittenberg et al, 1991). Previous research has examined the performance of clinical groups on individual items of selected Wechsler subtests, such as Picture Arrangement (Broder & Oresick, 1987) or Information (Norman & Wilensky, 1961) and has found that obtained rank orders of item difficulties do not correspond to those reported for the standardization group. For example, Broder and Oresick (1987) examined item difficulties on Picture Arrangement for a group of outpatients referred for psychological or neurological evaluation.…”

“…Previous research has examined the performance of clinical groups on individual items of selected Wechsler subtests, such as Picture Arrangement (Broder & Oresick, 1987) or Information (Norman & Wilensky, 1961) and has found that obtained rank orders of item difficulties do not correspond to those reported for the standardization group. For example, Broder and Oresick (1987) examined item difficulties on Picture Arrangement for a group of outpatients referred for psychological or neurological evaluation. The second Picture Arrangement item (FLIRT) was found to be the second most difficult item instead of the second easiest.…”

“…Thus, there is some evidence that WAIS-R item difficulty curves for clinical groups may differ from those of the standardization group. Broder and Oresick (1987) warned that "If Picture Arrangement (and other subtests) d o not conform to the expectation that WAIS-R items became increasingly difficult, then clinicians may erroneously interpret errors on early items as indicators of organic or functional disorder" (p. 1201). The present study examined the item difficulties of all subtests of the WAIS-R with a sample of psychiatric inpatients and identified those items that were significantly out of order relative to the WAIS-R standardization group.…”

The measurement and diagnostic utility of intrasubtest scatter in pediatric neuropsychology

“…Watson (1965) found no differences between WAIS ISS measured in patients with schizophrenia and in those with cerebral lesions. Boone (1992), when investigating WAIS-R ISS in a clinical sample mainly diagnosed with either schizophrenia or affective disorder, found the incidence of this measure of inconsistency to be less than that reported in the standardization sample. Mittenberg, Thompson, Schwartz, Ryan, and Levitt (1991) compared WAIS ISS in Alzheimer's patients with item variability measured in normal elderly controls and found diagnostic classification to be little better than chance.…”

“…One of the most commonly used measures of ISS is the cumulative absolute differences between consecutive item scores (Boone, 1992;Dumont & Willis, 1995;Feinberg & McIlvried, 1991;Kaplan et al, 1991). The main difficulty with this approach is that it allows no additional weighting for the degree of inconsistency evident in the item-person interaction.…”