A brief discussion of theories of general intelligence precedes a report of relevant empirical data. Results from the factor analysis of more than 20 sets of Wechsler Adult Intelligence Scale (WAIS) data indicate that the WAIS clearly is not a one-factor scale. It does not measure a single, general intelligence. Roughly 17 percent of the reliable…

Intended as a nontechnical review of current scientific knowledge in the field, this essay considers the nature of primary and secondary intellectual abilities, plus the major features of, and the development of individual differences in, the skills and capacities constituting intelligence. Part of a theme issue on intelligence. (Author/SJL)