three-stratum model of intelligence
a psychometric model of intelligence based on a factorial reanalysis of several hundred data sets available in the literature. It is considered by some researchers to be the most thoroughly supported of the various psychometric theories of intelligence. The three strata correspond to (a) minor group factors at the first (lowest) level; (b) major group factors at the second level (fluid intelligence, crystallized intelligence, general memory and learning, broad visual perception, broad auditory perception, broad retrieval ability, broad cognitive speediness, and processing speed); and (c) the general factor at the third (highest) level. [proposed in the 1990s by U.S. psychologist John B. Carroll (1916–2003)]