Ethnicity of Patients

with Lateralized Lesions

Researchers were slow to realize that gender differences among patients with unilateral lesions was a topic worthy of consideration. They have virtually ignored the issue of ethnic differences. To our knowledge, only one study has addressed this important issue, the doctoral dissertation in vestigation conducted by Munder (1976). Even though this study was executed quite well, included a substantial number of patients, and yielded provocative results, Munder's work has not been included in summaries of Wechsler research involving brain-damaged patients (Bornstein & Matarazzo, 1982, 1984; Inglis & Lawson, 1982; Matarazzo & Herman, 1985).

It is unusual, in fact, for investigators to indicate the ethnic breakdown of their samples, even for groups that are likely to include representative numbers of African Americans such as war veterans with missile wounds (e.g., Black, 1973, 1976). Even Lansdell, perhaps the earliest investigator to identify the importance of the variable of gender in brain lesion studies, failed to give the proportions of Caucasians and African Americans in his study of 150 men, many of whom had penetrating missile wounds (Lansdell & Smith, 1975).

Munder's Careful Investigation of V-P Differences for Caucasians and African Americans

Munder (1976) obtained her data by searching through psychological and medical records from a number of hospitals, selecting all brain-damaged males tested with a complete WAIS. Neurological diagnosis was arrived at independently of psychological test results for all patients based on some or all of the following criteria: EEG, brain scan surgery, autopsy. Patients with vision problems or incapacitating physical anomalies were not used in the study. Multiple analysis of covari-ance was used to control for age, years of education, and time interval between brain damage and date of testing.

The following numbers of male patients were investigated by Munder (1976): 25 Caucasians and 25 African Americans with left-hemisphere lesions, 25 Caucasians and 25 African Americans with right-hemisphere lesions, and 25 Caucasians and 25 African Americans with diffuse lesions

(total sample size of 150). All patients were aged 18 or above, and no patient had known brain damage prior to age 18; Munder (1976) did not, however, provide the mean age or age range for the groups. There was no attempt made to control for type of lesion, either by etiology or specific location.

Table 8.19 summarizes the results of Munder's study, using Verbal and Performance IQs that have been adjusted for the covariates. As indicated, the Caucasian men demonstrated the expected patterns of P > V and V > P for lesions to the left and right hemispheres, respectively. As was true for most studies in Tables 8.1-8.3, the mean V-P discrepancy was larger for Caucasian patients with right-brain damage (+15.1 points) than for those with left damage (-5.2 points). African American male patients with right damage showed the expected pattern of V > P (by +10.4 points), but African Americans with left lesions did not. Instead, the latter sample of adults evidenced a V-P IQ difference of +5.7 points.

Regardless of ethnicity, patients with diffuse brain damage obtained a mean difference of about 5 points favoring the Verbal Scale. Thus, adult African American male patients with brain damage displayed a V > P profile regardless of the location of the lesion, the same result reported for the patients studied by Todd et al. (1977). Differences shown between African Americans and

Caucasians in Table 8.19 were found by Munder (1976) to be statistically significant. Her analysis of covariance uncovered a significant interaction effect (.001 level) between ethnicity and location of brain damage on V- and P-IQs.

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