Access Type

Open Access Dissertation

Date of Award

January 2020

Degree Type


Degree Name



Communication Sciences and Disorders

First Advisor

Margaret L. Greenwald


A growing body of multidisciplinary research indicates the need for more holistic tests of executive cognitive functioning and complex language metrics that predict real-life performance. However, empirical studies investigating cognitive aging, limited capacity processing and everyday discourse behaviours are still lacking. The present research focused on ecologically valid methods for capturing individual differences in cognitive capacity and the effects of cognitive load on oral discourse processing (ODP) in healthy adult participants. This methodology sought to tease apart the nature of capacity limits and provide a better estimate of age-related differences in everyday discourse behaviors in three parts. First, the effects of simple and complex cognitive load and age-related differences in ODP performance were investigated using a dual-task paradigm. Second we examined, links between overall cognitive capacity—estimated via scores on a standardized self-report survey of everyday executive functioning—and dual-task ODP under varying load in younger and older adults. Finally, we explored the nature of capacity limits (i.e., scores on the self-report survey measuring particular executive functions) influencing age-related differences in ODP under varying load.

Results yielded evidence that age-related differences in ODP performance costs increased as the complexity of the dual-task condition increased. Results of our second inquiry did not support the prediction that overall cognitive capacity and ODP under complex load would be negatively correlated, and that this relationship would be greater for older adults. However, older adults’ mean scores indicated slightly reduced cognitive capacity and poorer ODP performance as the cognitive load increased. Results of the final analysis, while revealing weak-to-moderate and non-significant relationships, suggested that capacity limits in working memory, initiation, planning/organization, task monitoring, and organization of materials, influenced age-related declines in ODP performance.

Overall, findings add to literature advocating for ecologically valid cognitive-linguistic assessments. Combining dual-task performance measures with tests of executive functioning has the ability to tap individual differences in cognitive capacity and their relation to everyday discourse processing. Further, such methodologies promote a more holistic approach to assessing performance, which could strengthen the ability to predict meaningful behavioural patterns, and optimize intervention efforts for a diverse range of needs across adult populations.