Apprehension, Memory, and Fluid Intelligence Decline in Adulthood

Abstract

The principal results of three separate studies are described within the context of a recent formulation of the theory of fluid (Gf) and crystalized (Gc) intelligence. The focus of the report is on the adulthood decline of Gf. This decline is found to be in the vicinity of between 3 and 7 IQ points per decade over a period between roughly 30 and 60 years of age. The studies were designed to indicate the extert to which this decline could be explained as due to aging defects in processes of sensory detection, immediate apprehension, short-term memory, en-coding organization, attentiveness, concentration, hypothesis generation, speediness, carefulness, and persistence. The results suggested that Gf decline is associated mainly with defects in processes of organizing information; becoming alert to new information; ignoring irrelevancies; concentrating, maintaining, and dividing attention; and holding information in working memory. It seems that Gf decline mainly reflects loss of capacity, but decrease in inclination to "get up" for difficult tasks may also be involved, and there are possibilities that the results reflect, in part, cohort differences.