Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Neuroscience

Supervisor

Mitchell, Derek

Abstract

In times of emotional arousal, it is hypothesized that neural processes are triggered to “heighten” our senses to better respond to threatening stimuli. Some studies have tested this by exposing participants to emotional sounds to determine their impacts on visual acuity but have found mixed results. Previous studies have not investigated interactions between arousal induced by emotional sounds and visual acuity. Participants (N = 42) performed an orientation detection task while presented in silence or with sounds that varied in valence. Results displayed comparable accuracy across conditions but significantly faster response times during the presentation of negative sounds on the opposite side of the Gabor patch compared to neutral sounds irrespective of spatial location. Additionally, pupil size was significantly greater in the negative condition than in the neutral condition. These findings delineate how changes in arousal due to environmental factors can lead to changes in human performance.

Summary for Lay Audience

From athletes in professional sports to airline pilots, people are constantly exposed to emotional situations and have to perform at a high level. Although the impact of how emotional visual stimuli impact visual task performance is well understood, how emotional auditory stimuli impact visual task performance is unclear. Some studies find that emotional auditory stimuli can enhance task performance while other studies find that it disrupts performance or may have no effect at all. Furthermore, two factors that may affect these effects are when and where the auditory stimuli are presented in relation to the visual task stimuli. Moreover, physiological arousal may act as a mechanism by which these effects take place.

This study aims to explore how emotional auditory stimuli influence visual task performance using realistic sounds. Participants were recruited to complete a visual perception task in the presence of task-irrelevant emotional sounds. In the visual perception task, participants had to indicate whether a visual stimulus was tilted left or right by pressing the “F” or “J” key on the keyboard. To measure how physiological arousal was affected by emotional sounds, an eye tracker was used to record pupil dilation throughout the entire experiment.

Response times were faster in the presence of emotional sounds, especially when the emotional sounds were presented on the opposite side of the visual target stimulus. Accuracy was comparable between exposure to emotional and non-emotional sounds. Pupil dilation was larger for emotional sounds compared to non-emotional sounds confirming that emotional sounds lead to greater physiological arousal compared to non-emotional sounds. Sounds led to an overall reduction in response time compared to silence. However, emotional sounds led to a more prolonged enhancement in response time compared to non-emotional sounds. A similar trend was seen for pupil dilation. Overall, emotional sounds led to an enhancement in performance compared to non-emotional sounds and physiological arousal may act as a mechanism by which this occurs.

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