Forgetting numbers in old age: strategy and learning speed matter.
Memory intervention research with older adults has primarily focused on immediate effects of training. Little is known about whether memory training can prevent forgetting of a learned material over time. The main purpose of this study was to investigate the effects of memory training on forgetting of numerical information in old age. In addition, the effect of speed of learning on forgetting rate was examined. Two training programs were employed contrasting a number-consonant mnemonic strategy with a self-generated strategy. A non-practice control group was also included. There were 20 participants in each group (age range=60-83 years). Following completion of training, participants memorized six 4-digit numbers to perfection. Retention was tested after 30 min, 24 h, 7 weeks, and 8 months. The three groups showed equal rates of forgetting across the first two follow-up assessments. A different picture emerged for the last two occasions, with the self-generated strategy group remembering more items relative to the two other groups. Moreover, participants reaching the criterion in few trials exhibited less forgetting than slow learners. These data indicate that self-generated strategy training may have advantages over learning a classical mnemonic for preventing long-term forgetting of numeric materials in old age.