AGE, SPEED OF INFORMATION-PROCESSING, RECALL, AND FLUID INTELLIGENCE

On three occasions, 63 adults, ranging in age from 26 to 80 years, all in good health, were tested with three speed of information-processin g paradigms (the Sternberg, the Posner, and the Hick), two long-term f ree-recall tasks, and, as a measure of fluid intelligence, the Raven A dvanced Progressive Matrices (RAPM) test. Whereas within-condition lat encies for the three of the information-processing tasks and recall sc ores were found to be reliable and consistently correlated with age an d RAPM, individual differences in within-condition accuracies and betw een-condition slopes produced by the three information-processing task s were found to be unstable over time and unrelated to age and RAPM. A s suggested by Salthouse (1985), a large portion of the age-related di fferences in fluid intelligence was found to be accounted for by age-r elated declines in a general latency factor (cognitive speed). Further more, in agreement with Salthouse, this general latency factor appeare d to reflect more than what can be accounted for by the simplest of in formation-processing tasks (simple reaction time). Finally, given that free recall had a substantial independent effect on RAPM when age and latency were held constant, the results called into question the assu mption that cognitive speed can account for all individual differences in IQ.