Dissertations, Theses, and Capstone Projects

Date of Degree

6-2025

Document Type

Doctoral Dissertation

Degree Name

Doctor of Philosophy

Program

Speech-Language-Hearing Sciences

Advisor

Valerie Shafer

Committee Members

Mira Goral

Yan Helen Yu

Subject Categories

Applied Linguistics | Cognitive Neuroscience | Psycholinguistics and Neurolinguistics | Semantics and Pragmatics | Speech and Hearing Science

Keywords

Aging, Retrieval, Semantics, EEG, Neurolinguistics, Discourse

Abstract

There is ongoing debate about the locus of word retrieval deficits in aging, and how aging modifies the relationship between contextual processing and word production. Thematic relations among words (e.g., “sun” and “shell” are exemplars of the thematic category “beach”) are of particular interest in this domain because speakers must develop and maintain contextual representations to make use of them. This study uses the framework of the Swinging Lexical Network Hypothesis (SLNH; Abdel Rahman & Melinger, 2009, 2019) to a) determine whether thematic relations facilitate or interfere in word retrieval and b) explore whether the effects of thematic relations on retrieval are age-invariant or not. To this end, I employed a modified Blocked Cyclic Naming Paradigm where individuals were presented with a narrative establishing a thematic context, then named sets of items that were thematically related or unrelated. I examined behavioral and neural responses to images as individuals named words during initial word retrieval (cycle one) and repeated retrieval (cycles 2-6). Key manipulations included condition (related, unrelated), block order (related-first blocks where related items were named immediately after the narrative followed by unrelated items, and vice-versa for unrelated-first blocks), and age group (younger, older). The electroencephalogram (EEG) was recorded to monitor participants’ neural responses to each image prior to naming. The anterior Event-Related Potential (ERP) N2, which indexes conflict among response representations, was examined at frontal sites between 200 to 400 ms. Twenty-four younger and 23 healthy older adults completed the task. When naming a set of items for the first time in a block (cycle 1), there was an interaction between block order, condition, and age group. Specifically, in related-first blocks, related items were named faster than unrelated for both groups. In unrelated-first blocks, participants overall named unrelated items faster than related, however, younger adults experienced greater interference from related items than older adults. During repeated retrieval, both groups experienced facilitation from related items in related-first blocks and interference during unrelated-first blocks. With respect to the N2, there was a cross-over interaction between condition and block order for repeated retrieval only. During related-first blocks, N2 amplitudes were more negative for related compared to unrelated items. During unrelated-first blocks, N2 amplitudes were more negative for unrelated compared to related items. These findings suggest that, behaviorally, thematic relations may facilitate naming initially via conceptual priming but yield interference when encountered after priming decays. Moreover, the N2 findings suggest that context may modulate the application of controlled processing to manage interference among lexical competitors. Specifically, the temporal proximity between the narrative presentation and naming task heightens competition when related items are presented in close proximity. In sum, controlled processes are still recruited even when conceptual priming is high.

Download

This work is embargoed and will be available for download on Sunday, April 25, 2027

Share

COinS