Growing slower and less accurate: adult age differences in time-accuracy functions for recall and recognition from episodic memory.

In 2 experiments, time-accuracy curves were derived for recall and recognition from episodic memory for both young and older adults. In Experiment 1, time-accuracy functions were estimated for free list recall and list recall cued by rhyme words or semantic associations for 13 young and 13 older participants. In Experiment 2, time-accuracy functions were estimated for recognition of word lists with or without distractor items and with or without articulatory suppression for 29 young and 30 older participants. In both studies, age differences were found in the asymptote (i.e., the maximum level of performance attainable) and in the rate of approach toward the asymptote (i.e., the steepness of the curve). These two parameters were only modestly correlated. In Experiment 2, it was found that 89% of the age-related variance in the rate of approach and 62% of the age-related variance in the asymptote was explained by perceptual speed. The data point at the existence of 2 distinct effects of aging on episodic memory, namely a dynamic effect (growing slower) and an asymptotic effect (growing less accurate). The absence of Age x Condition interactions in the age-related parameters in either experiment points at the rather general nature of both aging effects.