Document Type

Honors Paper

Advisor

Jeff Moher

Publication Date

2026

Abstract

This thesis explores mental fatigue as a state arising from sustained cognitive demand and explores the use of the gradual-onset performance task (gradCPT) for mental fatigue research. The study examines whether expectancy effects (placebo or nocebo conditions) influence mental fatigue-related outcomes. Expectancy effects were induced by asking participants to view an inert optical illusion after describing its benefits (placebo) or harms (nocebo) to mental fatigue. Out of 73 participants, results showed significant decreases in performance over time, along with significantly increased subjective fatigue as measured by the VAS-F subscale, supporting gradCPT as an effective fatigue inducer in short periods of time. Manipulation score identified how much an individual believed in their respective expectancy effect of placebo (n=39) to nocebo (n=34). Manipulation score significantly predicted changes to subjective fatigue, however with inconsistent effect on behavioral outcomes.

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The views expressed in this paper are solely those of the author.