The present study examined the responses of 332 Kainai students ranging in age from 6 to 16 years to the Information, Arithmetic, and Picture Completion subtests of the Wechsler Intelligence Scale for Children-Revised (WISC-R) in order to determine the validity of these subtests as a measure of their intelligence. Two indices of validity were assessed: (a) subtest unidimensionality, and (b) order of item difficulty. With regard to the assumption of unidimensionality, examination of the data indicated low item-factor loadings on the Information, Arithmetic, and Picture Completion subtests. Examination of difficulty parameters revealed a nonlinear item difficulty order on all three subtests. These results support the conclusion of previous research that the WISC-R does not adequately assess the intelligence of Native children. Possible bases for the invalidity of the WISC-R for this population are discussed and recommendations for future research are presented.

Previous studies have found that poor effort can significantly impact psychometric performance by Traumatic Brain Injury (TBI) patients. So far, this impact has been relatively well studied in attention and memory. However, this is not the case for visual perception functions. Thus, the goal of this study was to determine to what extent TBI severity affect visual perception after controlling for effort. Results showed that mild TBI good effort group did not differ from a demographically matched control group. In contrast, a mild TBI poor effort group, a moderate-severe TBI group and a right hemisphere cerebro-vascular (CVA) group performed worse than the mild TBI good effort group and the control group. The results suggest a dose response relationship between injury severity and visual perception performance. After controlling for effort, results indicated that moderate-severe TBI, but not mild TBI, has long lasting effects on visual perception. Clinical implications are discussed.