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Access Type
WSU Access
Date of Award
January 2024
Degree Type
Dissertation
Degree Name
Ph.D.
Department
Psychology
First Advisor
John L. Woodard
Abstract
Introduction: Relational frame theory (RFT) is a theoretical framework which posits that the ability to derive implicit relations amongst stimuli is foundational to human cognition and language development. Stimulus equivalence tasks measure derived relational responding abilities by training a limited set of relations amongst stimuli and assessing recall for explicitly trained and implicitly derived stimulus relations. These tasks may be sensitive to identifying older adults (OA) at increased risk for dementia of the Alzheimer’s type (DAT), though this application has been scarcely researched. This study examined age differences in performance on a novel stimulus equivalence task and was the first to investigate how derived relational responding abilities change in OA with DAT risk factors. We predicted worse performance (i.e., slower and less accurate) on the stimulus equivalence task in younger adults (YA) relative to OA and in OA with a first-degree family history of DAT (OA+) relative to those without said history (OA-).
Method: Forty-four YA, 42 OA+, and 45 OA- completed the stimulus equivalence task and other measures of processing speed, episodic memory, associative learning, working memory, and crystallized intelligence. During the stimulus equivalence task, participants were taught two relations (e.g., A --> B, A --> C) between single English language letters (Letter condition) and abstract symbols (Symbol condition). Recall of the two trained and four derived relations (e.g., B --> A and C --> A, symmetry; B --> C and C --> B, transitivity) was subsequently tested. Accuracy rates and response time (RT) were recorded.
Results and Discussion: Overall, YA were faster and more accurate than OA- and exhibited greater learning across trials, consistent with cognitive aging literature demonstrating declines in processing speed, memory, and cognitive flexibility with age. Unexpectedly, no performance differences were observed between the cognitively healthy OA+ and OA- groups. This finding may be due to high cognitive reserve and lack of confirmed biomarkers for Alzheimer's disease in the OA+ group. All groups performed better when stimuli were familiar letters as opposed to abstract symbols. Derived relations were consistently recalled slower than trained relations in the YA group, whereas RT differences across relation types were only apparent in the Letter condition for the OA groups. Contrary to predictions, all groups were remarkably accurate even for the most complex transitivity relations, with minimal accuracy differences across relation types. These findings highlight the importance of examining RT rather than accuracy to detect more subtle cognitive weaknesses. Additionally, stimulus equivalence task performance was correlated with measures of associative learning, episodic memory, working memory, and processing speed, but not crystallized intelligence, supporting the task’s construct validity. While future research is needed in participants with diagnoses spanning the DAT continuum, this study offers promising preliminary results that the stimulus equivalence task may serve as a simple, cost-effective method for identifying age-related and possibly DAT risk-related cognitive decline.
Recommended Citation
Kadey, Kylie Rose, "Learning In The Absence Of Training: Examining Differential Age- And Alzheimer’s Disease Risk-Related Performance On A Stimulus Equivalence Task" (2024). Wayne State University Dissertations. 4095.
https://digitalcommons.wayne.edu/oa_dissertations/4095