Prychological Reporfr, 1992, 71, 483-487.

WAIS-R

O Psychological Reports 1992

SCATTER W I T H PSYCHIATRIC INPATIENTS: I. INTRASUBTEST SCATTER ', ' DANIEL E. BOONE Trenton Psychiairic Hospital

Summary.-Intrasubtest scatter values for eight WAIS-R subtests were estimated for a sampIe of 150 psychiatric inpatients and compared with those reported for a comarable portion of the WAIS-R standardization group by Kaplan, Fein, Morris, and Delis in 1991, using the normal deviate ( 2 ) 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.

The Wechsler Adult Intelligence Scale-Revised (WAIS-R; Wechsler, 1981) continues to be widely used in the intellectual and personality assessment of psychiatric inpatients (Boone, 1992; Piedmont, Sokolove, & Fleming, 1989a). I n addition to providing measures of over-all intellectual functioning and specific problem-solving abilities, WAIS-R performance patterns are thought to reflect personality dimensions, and, in some cases, clinical conditions (Matarazzo, 1772; Rapaport, Gill, & Schafer, 1968; Wechsler, 1958; Zimmerman & Woo-Sam, 1985). Attempts to differentiate normals and clinical groups on these features have usually focused on subtest profile patterns, also referred to as intersubtest scatter (e.g., Piedmont, Sokolove, & Fleming, 1989b) or as composite scale (i.e., Verbal and Performance) differences (e.g., Pernicano, 1986). Another approach in differentiating normals and clinical groups involves the examination of WAIS-R performance on individual items. This approach may involve a qualitative analysis of individual item responses (e.g., Weiner, 1966) or a quantitative analysis of the presence and amount of intrasubtest scatter (e.g., Mittenberg, Hammeke, & Rao, 1989; Mittenberg, Thompson, Schwartz, Ryan, & Levitt, 1991). Intrasubtest scatter refers to a pattern of failure on easy items and success on more difficult items and is thought to reflect intellectual loss (Lezak, 1983), organicity (KapIan, Fein, Morris, & Delis, 1991; Mittenberg, et al., 1771), or psychiatric disturbance (Kellerman & Burry, 1991). Rapaport, et al. (1968) popdarized the hypothesis that a large amount of intrasubtest scatter was suggestive of clinical conditions, particularly psychosis. This intrasubtest scatter was thought to reflect cognitive inefficiency, perhaps due to the temporary 'I thank all the psychologists and psychology interns for access to their testing files. 'Correspondence should be addressed to Daniel Roone, Ph.D., Drake Complex, Trenton Psychiatric Hospital, PO Box 7500, West Trenton, NJ 08628.

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or random interference from positive psychotic symptomatology or fluctuations in attention or concentration (Feinberg & McIlvried, 1991). In examining the significance of an obtained level of intrasubtest scatter for a particular patient, it is important to refer to the base rate of scatter present in the WAIS-R standardization group (Kaufman, 1990). The significance of this step in the assessment process was demonstrated by Mittenberg, et al. (1991), who found that the amount of intrasubtest scatter for a group of 32 patients with Alzheimer's dementia was actually less than that obtained for a group of normal elderly controls. Similar results were reported by Ryan, Paolo, and Smith (1992), who observed that the intersubtest scatter among 216 brain-damaged patients was no greater than that for the normal persons in the WAIS-R standardization group. The purpose of this study was to compare the amount of WAIS-R intrasubtest scatter for a sample of psychiatric inpatients with that for the WAIS-R standardization group. Specifically, the hypothesis that psychiatric inpatients would show more intrasubtest scatter than normals was examined. METHOD

Subjects One hundred and seven men (57 white, 43 black, 7 other) and 43 women (31 white, 9 black, 3 other) participated. They ranged in age from 18 to 64 years (mean age = 32.5, SD = 10.1) and were referred for intellectual assessment at a state-run psychiatric institution. Fifty percent of these patients were primarily diagnosed with a schizophrenic (50%) disorder, while 30% received a lagnosis of affective disorder. The remaining patients were diagnosed with either an organic condition (lo%), substance abuse problem (5%), or personality disorder (5%). The mean Full Scale I Q for this sample was 85.1 (SD= 15.1). Procedure Intrasubtest scatter values were calculated as follows. For each subtest, the absolute difference between two consecutive item scores was calculated, then summed, across all items within each subtest. This absolute difference is referred to as a scatter point (Kaplan, et al., 1991). For example, a 0 followed by a 1 or a 2 followed by a 1 equals 1 scatter point, while a 2 followed by a 0 equals 2 scatter points. The sum of the scatter points for a subtest is referred to as the subtest's scatter sco~e.Intrasubtest scatter scores were determined for d subtests except Digit Span, Object Assembly, and Digit Symbol, since intrasubtest scatter scores for these three subtests were not reported for the WAIS-R standardization group (Kaplan, et al., 1991). Other researchers have found that, for the WAIS-R standardization group, scatter indices vary in direct proportion to the Full Scale IQ. For example, Verbal-Performance differences (Matarazzo & Herman, 1984) and in-

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tersubtest scatter (Matarazzo, Daniel, Prifitera, & Herman, 1988; McLean, Kaufman, & Reynolds, 1989; McLean, Reynolds, & Kaufman, 1990) increase as the Full Scale I Q increases. I t can be assumed that this relationship holds true for intrasubtest scatter as well. I t was necessary then to compare intrasubtest scatter scores for psychiatric inpatients, who routinely have a Full Scale I Q approximately one standard deviation less than that of normals (Boone, 1992; Piedmont, et al., 1989b; Thompson, Howard, & Anderson, 1986), with those obtained by a comparable portion of the WAIS-R standardization group. Kaplan, et al. (1991) reported intrasubtest scatter scores for the standardization group according to the obtained subtest score within each subtest. Mean scaled-score values for psychiatric inpatients on all subtests were right at seven. Psychiatric inpatients' intrasubtest scatter scores were therefore compared with those reported for normals who obtained scaled scores of seven on a particular subtest (Kaplan, et al., 1991, Appendix A, pp. 116-135). Scatter scores on all subtests were compared with those values reported for the standardization group using the normal deviate (z) test. A Bonferroni correction was employed to control for the family-wise error rate associated with performing multiple comparisons. RESULTSAND DISCUSSION Scatter indices on each WAIS-R subtest for the standardization group and psychiatric inpatient sample are presented in Table 1, along with r e s d tant z values. Dividing alpha (.05) by the number of comparisons made (8) to control for the family-wise error rate, the critical value for x was set at 2.51. The standardization group's intrasubtest scatter scores were greater than those of the psychiatric inpatients across all subtests. With the exception of the Information and Arithmetic subtests, the standardization group's intrasubtest scatter values were significantly greater than those for psychiatric inpatients. Contrary to expectation, psychiatric inpatients did not show more intrasubtest scatter than a comparable portion of the WAIS-R standardization group. The amount of intrasubtest scatter shown by the inpatient sample was significantly less than that for normals on six of eight subtests, c&ng into question the use of WAIS-R intrasubtest scatter as a way of identifying psychiatric inpatients. As with Verbal-Performance discrepancies and intersubtest scatter base rates on the WAIS-R (Matarazzo, et a/., 1988; Matarazzo & Herman, 1984; McLean, et al., 1989, 1990), WISC-R (Kaufman, 1976), and WPPSI (Reynolds & Gutkin, 1981), it appears that a certain amount of intrasubtest scatter is expected in normal, nonclinical groups. Normal performance on Wechsler's scales is characterized by variability across items, subtests, and scales. Conversely, clinical conditions (e.g., psychiatric disturbance, organicity) may affect intellectual functioning consistently, across all items within each subtest, rather than on a temporary, random,

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D. E. BOONE TABLE 1 STAWDARDIZA~ON GROWAND PSYCHIATNCINPATIENTINTRASL~BTEST SCATERSCORE MEANS,STANDARD DEVIA~ONS, AND TESTOF SIGNIFICANCE

WAIS-R

Subtest

Standardization Groupt M SD

Psychiatric Inpatients N = 150

z

Information 6.8 Picture Completion 7.7 Picture Arrangement 8.8 Vocabulary 15.9 Block Design 9.0 Arithmetic 3.1 Comprehension 10.3 Similarities 10.1 *p