Plasticity of inhibition in old age: durability, practice and transfer effects

Abstract

Empirical research indicates age-related declines in three sub-functions of inhibition: access (keeping irrelevant information outside one's focus of attention), deletion (ridding working memory of no longer relevant information), and restraint (withholding automatic responses that are not appropriate for the task at hand). Although single-task inhibition training has been previously explored using a six-session Stroop task program, no research has been done to examine long-term durability of the practice gains or the impact of a multi-task approach to inhibition training in older adults. This dissertation fills these gaps in the literature with three studies. The first study evaluates the maintenance of Stroop training one and three years following initial training and finds evidence in support of long-term durability of single-task inhibition training in older adults. The remaining two studies explored the benefits of training all three sub-functions of inhibition in older adults. First, study 2 seeks to confirm the presence of age differences in all three sub-functions of inhibition - supporting a rationale for training these abilities in older adults. Last, study 3 examines the plasticity of all three sub-functions of inhibition in older adults across six retest practice sessions, and three levels of associated transfer: near-near (transfer to the tasks used at training, but with varying items), near (transfer to tasks that were not trained, but tap the same abilities as the training tasks), and far (transfer to tasks that were trained and tap abilities different from those trained). The findings indicate the older adults show retest practice gains in all three sub-functions of inhibition. Furthermore, strong evidence supports near-near transfer, while there is limited support for near transfer and no support for far transfer effects in older adults following three sub-functions of inhibition training. Taken together these studies contribute to the cognitive aging literature by evaluating several key features of plasticity in inhibition, including durability of training effects, retest practice and transfer effects. These findings have implications for the development of effective cognitive training programs in older adults.