Acquisition, recall, and forgetting of verbal information in long-term memory by young, middle-aged, and elderly individuals.

Memory performance by four age groups (30-45 years, 46-60 years, 61-75 years, and 76-90 years) was compared on a multi-trial verbal recall task with 20-minute and 1-day delay free recall and recognition trials. The rate of acquisition across 5 learning trials was similar for all ages except the youngest group whose performance was constrained by a ceiling effect. The level of acquisition achieved was less in the two oldest groups. Words gained across trials and words lost across trials made similar contributions to the shape of the learning curve for the acquisition trials. Subjective organization decreased with age, but remained strongly related to the number of words recalled during acquisition for all age groups. The two oldest age groups demonstrated significant declines in words recalled on the 20-minute and 1-day delay trials. A subset of the oldest group demonstrated more rapid forgetting at the 1-day delay when participants from all age conditions were matched on acquisition. Thus, many aspects of free recall were impaired with age, and variance measurement of recall showed greater inter-individual differences with increasing age. This increase in individual differences could reflect a single form of age-related memory impairment, or it could indicate that memory impairment in the elderly is due to multiple processes. The importance of testing across the life span and using tests that examine a variety of memory components and processes for establishing norms and clarifying age-related deficits are discussed.