Date of Award
Kinesiology and Health Science
People choose actions based on many different variables. In particular, choice of posture while grasping an object typically depends upon several factors including the time spent in that posture, what postures were held prior to choosing that posture, and the precision required by the posture. The purpose of this study was to test a trade-off between choice of end-state comfort based on time spent in a posture at the beginning-state and the precision requirement of the end-state. A comfortable grasp is classified when a person has a full grasp on an object with their thumb pointing up. This posture also puts the wrist in its joint midrange which allows for more control (or precision). This means that a comfortable posture often affords the most precision in movement as well. To determine the trade-off between choice of comfort and choice of precision, we varied how long a subject had to hold the beginning state before moving an object to an end location (a hole). We made the end-state precision either small or large. When the requirement was to hold the initial grasp longer, and the end-target was large, we predicted that we would see more comfortable postures adopted at the beginning state, whereas, when the final placement was small and the initial posture was not constrained, we predicted we would see comfort adopted at the end state. A choice of comfort or precision would be demanded by the conditions with long beginning-state hold times and high precision demands. We aimed to determine which aspect of movement was of greater importance to individuals, overall comfort or precision. We found that as beginning-state grasp time increased, individuals adopted a beginning-state comfort grasp which minimized their precision at the end-state. This was true for both small targets and large targets. We also found a difference between grasp choices for large and small targets when the beginning-state grasp time was constrained under 5 seconds. Individuals maintained an end-state comfort grasp technique longer with the small target (high precision) versus the large target (low precision).
Gamble, Tucker Gregory, "Choice of End State Comfort Based on Time Spent at the Beginning State and the Precision Requirement of the End State" (2020). Undergraduate Honors Capstone Projects. 865.
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Departmental Honors Advisor