Date of Award
Doctor of Philosophy (PhD)
In a series of studies, I examined the degree to which fluid and crystallized abilities contribute to and interact during speech perception. During the aging process, crystallized abilities (e.g., linguistic and word knowledge) are largely preserved, while fluid abilities involved in the online manipulation of information (e.g., working memory and inhibitory control) decline with age. Importantly, these two components are critical for successful speech perception and comprehension. While prior research has proposed that older adults rely on crystallized knowledge to compensate for cognitive deficits in difficult listening conditions, this hypothesis has not been directly tested. Younger and older adults completed a series of speech-in-noise identification tasks, in which they were presented with single-words and sentences in a noisy background and asked to identify key targets. Critically, I concurrently manipulated variables reflecting fluid demands (working memory and inhibitory demands) and crystallized support (linguistic knowledge in the form of semantic context and word frequency) across trials. The results showed that age differences in performance were greatly reduced for conditions in which linguistic support, i.e., predictable semantic context and highly frequent words, were present. That is, high linguistic support appeared to moderate increased cognitive task demands, showing a direct demonstration of linguistic compensation. In some cases, older adults' performance even exceeded that of younger adults. These results are the first to directly demonstrate how older adults use linguistic knowledge to mitigate the effects of increased cognitive difficulty associated with challenging listening situations during speech perception. The results further shed light on the complex mechanisms underlying cognitive aging and the factors which contribute to speech processing across the lifespan.
Chair and Committee
Mitchell S. Sommers
David A. Balota, Sandra S. Hale, Jonathan E. Peelle, Nancy Tye-Murray,
Dey, Avanti, "The Interaction of Crystallized and Fluid Abilities in Aging and Speech Perception" (2016). Arts & Sciences Electronic Theses and Dissertations. 784.