Reaching a Decision: Cognitive vs. Physical Effort Trade-offs in a Motor Task

Abstract

In our everyday lives, we continuously exert effort to accomplish tasks. This effort is present across an effort spectrum, ranging from seemingly small tasks, such as opening a door, to large tasks, such as competing in an Olympic swimming race. Two types of effort commonly exerted are cognitive effort (CE) and physical effort (PE), many tasks require a combination of both effort types. According to the Principle of Least Effort, this simultaneous exertion indicates that there should be some trade-off in CE exertion vs. PE exertion to minimize overall effort expenditure, although few studies have developed methods to sufficiently compare the two types of effort. The present study aimed to measure potential CE vs. PE preferences and trade-offs using a reaching task, where participants counteracted varying levels, ranging from no-effort to high-effort, of a CE measure (a visuomotor rotation task) and a PE measure (a resistive force task). Results indicated that participants preferred lower-effort options for both rotation and force, although rotation magnitude and rotation difference dominated choice behavior, indicating that participants avoided exerting more CE. Time variables (decision time, reaction time, and movement time), as well as angular error, were used to help explain this finding. Limitations of the study and future directions are discussed.