Short-Term Memory and Crystallized-Fluid Intelligence in Adulthood

To assess the contributions of two types of short-term memory (STM)-passive span of apprehension and working memory-to the intellectual, (that is, fluid [Gf] and crystallized [Gc]) functioning of adults and age differences therein, data from a test battery assessing STM, Gf, and Gc administered to three (n = 54) groups of adults, aged 17-26, 39-51, and 59-76 years (N = 162), were analyzed. Measures of STM and Gf showed substantial and significant negative relationships with age, while the Gc-age relations were significantly positive, but weak. Age declines in Gf functioning appear related to working STM (as measured by backward digits) deficits but not to passive STM (as measured by forward digits) deficits. In contrast to previous literature suggesting that memory span tasks have little utility as measures of STM deficits among the aged, these results suggest great utility if the forward versus backward memory span distinction is maintained.