The two-level theory of mental abilities posits two broad classes of ability: level I (learning and memory) and level II (the "g" factor of intelligence tests, reasoning, abstraction, and problem solving). Levels I and II are hypothesized to interact with SES and/or race such that: (l) SES differences are greater for level II than for I,…

The purpose of this study was to attempt to determine if score gains obtained upon repeated testing with an intelligence test result from a practice effect, from students remembering specific items, or from a combination of both. The verbal and nonverbal batteries of an I.Q. test were administered to 860 sixth graders on three occasions with…