The general aim of this thesis was to further our understanding of episodic memory plasticity in normal aging, by examining the effectiveness of a mnemonic-strategy training program versus a self-generated memory strategy training program in healthy adults between 20 and 90 years old, using numeric materials. The effectiveness of training was evaluated in terms of immediate gains, transfer of skill, maintenance of skill, and forgetting of learned information. The thesis also addressed age differences in memory plasticity.
Study I compared two different memory-training approaches: Memory training with a classic mnemonic strategy (the number-consonant mnemonic) versus self-generated memory strategies in healthy older adults. The findings demonstrated intervention-related gains in both training groups. The magnitude of improvement increased in both groups when cognitive support was provided. Transfer of skills to tasks not encountered during training was not demonstrated.
Study II examined maintenance of skills following these two forms of training: mnemonic and self-generated. This was accomplished by reassessing participants from Study 1 eight months after completion of training. The results demonstrate maintenance effects for both training groups over the eight months follow-up period under supported task conditions. However, when cognitive support was withdrawn, recall performance for the mnemonic group decreased over time, whereas performance for the self-generated strategy group was not affected negatively.
Study III investigated the effects of memory training on forgetting of numerical information in old age. The moderating effect of learning speed on forgetting rate was also examined. Following completion of training, participants memorized six numbers to perfection. Retention was tested after 30 minutes, 24 hours, 7 weeks, and 8 months. Results show that the groups showed equal rates of forgetting across the first two followup assessments. A different picture emerged at the last two occasions, where the selfgenerated strategy group remembered more items relative to the mnemonic and control groups. Also, participants who achieved perfect recall in fewer trials exhibited less forgetting than slower learners.
Study IV examined adult age differences in episodic memory plasticity, with regard to overall gains as well as gains across trials as a function of training and cognitive support. Transfer of skills to tasks not encountered during training was also analysed. Results reveal age-limits in memory plasticity on several fronts. First, reductions of plasticity were not only evident between groups of young and older adults, but also within the group of older adults, showing that limits to plasticity were especially marked in very-old age. Further, age differences were not reduced under highly supported task conditions (more trials or verbal cues). Also, young adults exhibited greater transfer of skill in tasks not trained.
In summary, healthy older adults have a cognitive reserve capacity that can be elicited through memory training, and that self-generated strategy training might result in more durable effects compared to mnemonic training in old age. In planning memory interventions, age-differences in episodic memory plasticity and issues of cognitive support also need to be considered.
© Anna Derwinger, 2005