In the 1940's two forms of intelligence, fluid and crystallized, were postulated. Active mental processing (WAIS performance subtests) were fluid while well learned abilities (WAIS verbal subtests) were crystallized. Brain damage was considered to affect fluid abilities more than crystallized. WAIS scores comparing normal and diffusely organically damaged subjects indicated that, as hypothesized, the verbal subtests were more affected than the performance subtests.
HalsteadW. C.Brain and intelligence. Chicago: Univer. of Chicago Press, 1947.
3.
HebbD. O.Clinical evidence concerning the nature of normal adult test performance. Psychological Bulletin, 1941, 38, 593. (Abstract)
4.
HebbD. O.The organization of behavior. New York: Wiley, 1949.
5.
HornJ. L.Human abilities: A review of research and theory in the early 1970's. Annual Review of Psychology, 1976, 27, 437–485.
6.
RussellE. W.The effect of acute lateralized brain damage on a factor analysis of the Wechsler-Bellevue Intelligence Test. Proceedings, 80th Annual Convention of the American Psychological Association, 1972, 8, 421–422.
