Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Psychology

Supervisor

Stevenson, Ryan A.

Abstract

Human multisensory experiences with the world rely on a combination of top-down and bottom-up influences, a process that changes throughout development. The present study explored the relationship between multisensory associative learning and multisensory integration using encephalography (EEG) and behavioural measures. While recording EEG activity, participants were exposed to novel pairings of non-sociolinguistic audiovisual stimuli of varying presentation probability while performing a detection task. The same stimuli were then used in another detection task, which was followed by an analogous behavioural speeded-response task, both of which kept probabilities equal and tested for multisensory integration. Significant relationships were found in fronto-central and occipital areas between late measures of associative learning and both early and late indices of multisensory integration in frontal and centro-parietal areas, respectively. Furthermore, a significant relationship was found between the behavioural and early neural index of multisensory integration. These results highlight the influence of higher-order processes, namely, learned associations on multisensory integration.

Summary for Lay Audience

Our experiences with the world with our senses rely on many things. What we already know about our environment is based on previous experiences with it, but also on different cues that tell us if multiple events we experience through our senses make up one event when combined, or separate events. In this study, we were interested in how learning to associate different events from our senses relates to how our brains know what events to perceive as one, or separate events. We used electrodes placed on the head to record brain activity while participants took part in our experiment. The participants saw shapes that were shown at the same time as tones and were asked to respond with their finger when they detected a specific pair. The likelihood of seeing the pairings is what we manipulated. Then, they were shown the same shapes and tones either together or separately and were simply asked to answer when they saw a red cross on the screen. Finally, they were shown the separate and paired shapes and tones and asked to respond with their finger as soon as they heard a tone or saw a shape. In this last part, we recorded how fast their responses were. As we expected, we found that individuals who learned pairs of shapes and tone well were also better at integrating information from different senses. We also found that how fast they were at responding was significantly related to how well their brain did this integration. This study shows the influence of our learning abilities for pairs of events from different senses on how well our brains integrate that information to simplify how we interact with the world.

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