Abstracts Category : Other

Neural Processes Underlying Auditory Context Effects

by Breanne Yerkes

Auditory information within our natural environments is disorganized and often ambiguous, leaving our auditory systems with a complex task: organizing sound into coherent objects. The auditory system uses both current and prior information to assist in completing this task. The influences of previous context on current perception have been referred to as context effects. A contrastive context effect results in a current perception that is opposite of what is expected based on the physical stimulus properties presented during an immediate context. A facilitative context effect results in a current perception that is the same as the perception during the immediate context. These two context effects were used in the current study to investigate (1) whether they are present during a concurrent sound segregation task (2) whether they arise from the same or different neural processes. Participants completed a concurrent sound segregation task while electrical brain activity was being recorded using electroencephalography (EEG). During the concurrent sound segregation task, participants were presented with sounds and indicated whether they perceived one or two auditory objects, revealing how simultaneous sounds are organized. Behaviorally, results indicated a strong presence of the facilitative effect; however, no contrastive effect was present. Electrophysiologically, results showed no significant contrastive effect and due to an inadequate amount of trials, the facilitative effect was not able to be analyzed. The stimulus parameters used in the current study elicited a strong facilitative effect but no contrastive effect, highlighting a fundamental difference. The specific stimulus parameters used and the resulting outcomes indicate the facilitative effect is more persistent and less susceptible to interference than the contrastive effect. Advisors/Committee Members: Joel S. Snyder, Erin Hannon, James Hyman, William Ramsey.