"Psychometric intelligence" is not equivalent to "crystallized intelligence," nor is it insensitive to presence of brain damage: a reply to Russell.

Whether Halstead's (1947) distinction between biologic and psychometric intelligence and Cattell's (1963) theory of fluid and crystallized intelligence reflect the same underlying constructs is an interesting question and has heuristic value. To address that question experimentally, however, requires factor-analytic and other higher-order correlative analysis with careful clinical syndrome characterization. We argue that Halstead's and Cattell's characterizations of test attributes into distinct domains are not equivalent, and that the proposal of their equivalence cannot be properly evaluated based solely on test battery sensitivity to brain damage.