Level I and Level II Abilities in Three Ethnic Groups 1

A large battery of various tests of intelligence, scholastic achievement, and short-term memory was administered to some 2,000 white, Negro and Mexican-American pupils in grades, 4,5, and 6 in a largely agricultural school district in the central valley of California. The three grades were used as separate replications of the study. Factor analysis (i.e., principal components) with oblique rotation yielded three main factors, identified as fluid (g _f ) and crystalized (g _c ) intelligence (both are aspects of Level II ability in Jensen's theory) and a memory factor (a Level I ability). Mean factor scores for the three ethnic groups differed significantly and showed significant interactions with ethnicity largely in accord with expectations from Jensen's two-level theory of abilities. The white and Negro groups differed markedly in g _c and g _f but not in memory; the white and Mexican groups differed markedly in g _c , and much less in g _f and memory. The Negro and Mexican groups differed the most in g _f but only slightly in g _c . There were also systematic ethnic group differences in the pattern of intercorrelations among factor scores, and in the correlations of the factor scores with an index of socioeconomic status. The results are discussed in relation to Jensen's two-level theory of mental abilities and Cattell's theory of fluid and crystalized intelligence.