Document Type

Thesis

Degree Name

Master of Science (MSc)

Department

Kinesiology and Physical Education

Faculty/School

Faculty of Science

First Advisor

Michael Cinelli, PhD

Advisor Role

Thesis Supervisor

Abstract

Changes to an individual’s physical or cognitive state can influence their perception of action capabilities. Collision avoidance tasks provide a way to assess these perceptual changes under varying conditions. For example, Snyder and Cinelli (2019) found that physical fatigue slowed response time during a collision avoidance task. Mental fatigue, induced by long periods of demanding cognitive activity, may have similar effects, as it has been shown to impair performance on cognitively demanding tasks (Kunasegaran et al., 2023). Interestingly, research comparing athletes and non-athletes suggests that athletes may be more resistant to the effects of mental fatigue (Jaydari Fard et al., 2019). Despite evidence that mental fatigue affects males and females similarly (Jaydari Fard & Lavender, 2018), much of the past research has focused exclusively on male participants.

While the effects of physical fatigue on decision-making for collision avoidance tasks are established, the effects of mental fatigue remain underexplored, especially in female athletes. Therefore, the aim of this thesis was to investigate the effects of mental fatigue on decision-making during a collision avoidance task and determine whether male and female rugby players exhibit similar levels of resistance. Study One compared mentally fatigued non-athlete participants with a Control group, while Study Two investigated sex differences among fatigued varsity rugby players.

For Study One, twenty-six participants were randomly allocated to either the Mental Fatigue or Control group. Participants completed a virtual reality crossing order task, where they walked toward a doorway while a virtual person (VP) approached from the opposite direction. When the screen went blank, they responded whether they would pass first. Following this, the Mental Fatigue group completed a 30-minute Stroop task, while the Control group watched a 30-minute documentary. Participants then repeated the crossing order task. It was hypothesized that performance would decrease following mental fatigue and when the VP’s approach speed closely matched the participants’ own walking speed. The findings revealed that participants’ performance improved across both groups. However, accuracy was significantly lower when the VP approached at 1.1x the participant’s walking speed.

For Study Two, eighteen (9 male, 9 female) varsity rugby players completed the same procedure as the Mental Fatigue group in Study One. It was hypothesized that decision-making performance would decrease following the Stroop task and during conditions where the VP’s approach speed closely matched their own walking speed. Additionally, no sex differences in performance were expected. The results revealed that athletes maintained their performance despite being fatigued. However, they were less accurate when the VP’s approach speed was 1.1x their walking speed. Interestingly, female rugby players exhibited faster response times than males.

In conclusion, mental fatigue did not impair decision-making on this task, possibly because the cognitive demands of the task were insufficient to reveal fatigue-related effects. Additionally, requiring participants to make a binary decision at a fixed point likely simplified the perceptual demands of the task. However, accuracy was lowest when the VP approached at 1.1x the participant’s walking speed, possibly due to participants walking faster than their calculated average speed as they adapted to walking in the virtual environment. The sex differences in response time could possibly reflect differences in cognitive processing. Future research should explore more cognitively demanding tasks involving complex decision-making to better understand how mental fatigue and sex-based differences influence perceptual judgements.

Convocation Year

2025

Convocation Season

Fall

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Available for download on Thursday, July 27, 2028

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