Investigation of Inhibitory and Facilitatory Attentional Mechanisms in Cognitive Aging

Abstract

It is well understood that human cognition declines with age. While much research has explored cognitive decline in the elderly, it is still unknown as to what specific mechanisms underpin this decline. Processing speed theory (Salthouse, 1996) would suggest that any observed differences between elderly and young adult samples are due to a generalized slowing of information processing. On the other hand, inhibitory deficit theory (Hasher & Zacks, 1988) posits that any age related decline in cognition is not related to a general slowdown, but rather to deficits in inhibitory control. The research in this thesis used a dual-task paradigm that has the ability to examine both inhibitory and facilitatory attentional mechanisms in both younger and older adult populations. Overall, the findings from two experiments provide support for both of the theoretical standpoints used to explain cognitive decline. That is, there was evidence for a general slowdown in information processing (Experiments 1 and 2) as well as a disturbance in inhibitory processes (Experiment 1). Thus, it appears that both theories may account for the cognitive decline, at least as measured with these experimental paradigms. The findings also provide evidence for a separate facilitatory attentional mechanism that appears to be less susceptible to age related decline.