Table 8.20 looks at the 11 WAIS subtests by race, comparing the mean scaled scores earned by patients with left lesions with the mean scaled scores earned by patients with right lesions. It was not meaningful to compare Caucasian patients with left lesions to African American patients with left lesions because the Caucasian patients scored significantly and substantially higher than African American patients on all WAIS IQs (Munder, 1976).
In Table 8.20, the scaled scores are different from the scores shown for the same groups in Table 8.9. The Table 8.9 scaled scores are the actual, observed values, which are appropriate to report for an accumulation of data across studies. For the present analysis, however, which aims to clarify to the degree possible an understanding of the interaction with ethnicity, it made more sense to control for extraneous variables; hence, the scaled scores shown in Table 8.20 have been
TABLE 8.19 V-P IQ discrepancies on the WAIS for separate groups of African American and Caucasian patients displaying localized or diffuse lesions
Left Lesions Right Lesions Diffuse Lesions
Mean Mean V-P Mean Mean V-P Mean Mean V-P Group V-IQ P-IQ Dif. V-IQ P-IQ Dif. V-IQ P-IQ Dif.
Blacks 87.4 81.7 +5.7 91.5 81.1 +10.4 90.8 86.3 +4.5
Whites 92.5 97.7 -5.2 101.6 86.5 +15.1 97.5 91.2 +6.3
Total group 90.0 89.7 +0.3 96.5 83.8 +12.7 94.1 88.7 +5.4
Note: Data are from Munder (1976). The sample is com- were covaried: chronological age, years of education, and time posed of 150 adult males: 2 5 from each race in each brain-dam- interval between the onset of the brain damage and the psycho-
age category. The mean IQs are adjusted values, based on a logical testing. multiple analysis of covariance in which the following variables
TABLE 8.20 Mean scaled scores on the WAIS earned by African American males and Caucasian males with unilateral brain damage
Left Right Left Right
Lesion Lesion Mean Lesion Lesion Mean
Verbal 7.6 8.4
Note: Mean Diff. = mean for left lesion minus mean for right lesion. Data are from Munder (1976). Mean scaled scores in this table are values that have been adjusted for three covari-
adjusted for three covariates: age, education, and interval between brain damage and date of testing.
The comparisons shown in Table 8.20 indicate that 9 of the 11 subtests behaved as predicted for Caucasians, but only four subtests (all Verbal) behaved as hypothesized for African Americans. That is to say, one would anticipate patients with left lesions to outscore patients with right lesions on Performance subtests, but to perform more poorly on Verbal subtests.
For Caucasians, substantial differences in the predicted directions were observed between the two patient groups on all tasks except Informa-
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