Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Neuroscience

Supervisor

Mitchell, Derek G. V.

Abstract

Emotional stimuli can disrupt or enhance task performance, and this may depend on the sensory modality involved. In unimodal paradigms (e.g. visual task-irrelevant stimuli during a visual task) emotional stimuli frequently produce distraction effects; it is unclear how emotion affects task performance in cross-modal paradigms (e.g. auditory stimuli during a visual task). This project explored task performance as a function of sensory modality and emotional valence. In Study 1, participants (N=50) completed a visual task in the presence of task-irrelevant negative and neutral images and sounds. Response times and accuracy were disrupted in the presence of visual but not auditory emotional stimuli, particularly when the target and task-irrelevant stimulus appeared simultaneously. In Study 2, participants (N=38) completed an equivalent auditory task. Response times and accuracy were enhanced in the presence of auditory emotional stimuli at the first timepoint but disrupted at later timepoints. There was no effect for visual stimuli.

Summary for Lay Audience

Emotional information (e.g. emotional facial expressions, threatening animals, explosions) is said to have preferential access to processing resources. This advantage makes it more likely to capture attention and be perceived effectively, compared to neutral information. Many studies have examined how emotional information impacts task performance, but a lot still remains unknown. In some cases, the presence of emotional information is detrimental to performance, while in others it is beneficial. This depends on many factors; one important factor might be the sensory modality through which the task and the task-irrelevant emotional information are presented. Specifically, in unimodal paradigms (e.g. visual task-irrelevant stimuli during a visual task) emotional stimuli frequently produce distraction effects; however, not many studies have examined the effect of emotional content in cross-modal paradigms (e.g. auditory task-irrelevant stimuli during a visual task).

This study is the first to directly compare the impact of emotional content on task performance in unimodal and cross-modal blocks, using realistic images and sounds. Participants were recruited to complete a visual perception task in the presence of task-irrelevant emotional and neutral images and sounds. On the visual detection task, participants indicated on which side of the screen a target stimulus appeared on each trial via button press. Response times and accuracy were worse in the presence of visual but not auditory emotional stimuli, especially when the target and task-irrelevant stimulus appeared at the same time.

A follow-up experiment used an auditory perception task to determine whether these findings extended to tasks presented through other modalities. Participants listened to white noise through headphones and were asked to indicate on which side there was a sound modulation. Accuracy was disrupted in the presence of auditory but not visual emotional stimuli. In the unimodal condition, when targets and task-irrelevant stimuli appeared at the same time, emotional stimuli actually enhanced performance; however, when the targets appeared slightly later, emotion caused a distracting effect. Overall, emotional content produced distraction effects in unimodal but not cross-modal blocks; however, this effect was not consistent over time, and future studies should further examine the time courses of emotional distraction and enhancement.

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