Verbal Memory Through the Looking Glass: The Impact of Encoding Strategy, Age, and Hemispheric Biases on Memory for Physical Form

This thesis examines the ability to retain from a stimulus both its specific appearance and the general information it coveys, with particular attention to how this ability changes across the lifespan, and might be represented within the brain. In the first two experiments, event-related potentials (ERPs) were recorded as younger (Experiment 1) and older (Experiment 2) adults attempted to recognize words that were tested in the same or opposite letter case as they had been studied in. Across both age groups, participant-selected encoding strategies dominated the pattern of results, revealing strategy-dependent neural indices of form overlap that were age invariant. In the second set of experiments, study words were presented to the left or right visual field, biasing encoding to the left (LH) or right cerebral hemisphere (RH). In all four experiments in this series, test words appeared in either the same (same-case) or opposite (different-case) letter case as the corresponding study item; the required response varied across experiments. When participants were instructed to endorse all repeated words regardless of case match, recognition of repeated items showed a same-case advantage that was greater for words initially studied by the LH in both accuracy (Experiment 3) and ERP memory signals (Experiment 4), and this effect was limited to short repetition lags. When participants were required to endorse only same-case repeated items and to reject different-case and new words (Experiment 5), words studied in the RH were better discriminated on the basis of case match at test. Experiments 3-5 support previous evidence that the LH is better at retaining generic information, whereas the RH is better at retaining specific details such as letter case. In Experiment 6, however, participants were presented with the uppercase and lowercase versions of repeated words, and instructed to select the studied letter case; the absence of any visual field effect in this design suggests that asymmetries apparent in previous experiments were more reflective of task demands than memory ability. In sum, this thesis finds that age-related effects and hemispheric differences seen in the ability to retrieve form details may be driven primarily by encoding and retrieval strategies.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Psychology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Evans, Karen Marie

Contributors dc:contributor

• Kara Federmeier

• Health Sciences, Aging

Language dc:language

eng

Identifier

(MiAaPQ)AAI3392008

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/82181