Comparing the Performance of Native North Americans and Predominantly White Military Recruits on Verbal and Nonverbal Measures of Cognitive Ability

This study compared the cognitive ability of adult Canadian First Nations (American Indian) aboriginals (N=101) living in remote areas to recruits (N=131) undergoing military training in the Canadian Forces. Comparisons involved both verbal and nonverbal measures: The Canadian Forces Aptitude Test (CFAT), Wonderlic Personnel Test, (WPT), Raven's Standard Progressive Matrices (SPM) and Mill Hill Vocabulary (MHV) test. All measures were examined for differential test and item functioning; as well, the CFAT was analyzed for adverse impact. Confirming past research, First Nations (FNs) members scored, on average, 18 points lower in IQ estimates based on the WPT, a verbal measure of cognitive ability; however, the differences between the groups were less on the nonverbal tests: SPM (5 points lower) and the MHV (9 points lower). Differential Item Functioning (DIF) analysis detected a few items from the CFAT, SPM and MHV that displayed DIF, but none from the WPT. The SPM and WPT appear to be unbiased measures with respect to differential test functioning (DTF), once language and education are controlled. Making employment decisions solely on verbal cognitive ability test scores, however, is likely to produce adverse impact against members of FN, unless verbal ability is a bona fide occupational requirement for the positions under consideration. Both the verbal and nonverbal cognitive ability tests assessed the same latent structure suggesting that the nonverbal tests could be used in place of the verbal tests with little loss in predictive ability for occupations involving a high degree of spatial ability.