MOTOR PSYCHOPHYSICS: DEVELOPING A METHOD FOR MEASURING MOVEMENT-RELATED EFFORT

Open Access
Author:
Coelho, Chason Joseph
Graduate Program:
Psychology
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
December 10, 2010
Committee Members:
  • David A. Rosenbaum, Thesis Advisor
Keywords:
  • human motor control
  • movement planning
  • psychophysical movement costs
  • effort
Abstract:
Motor planning theories suggest that the movements people perform are generally less effortful than the alternatives that could complete the task at hand. However, there is no established method for estimating movement-related effort. I used a task-choice method to address this challenge. On each trial, I presented participants with two paced back-and-forth object displacement tasks that varied along well defined dimensions. I asked participants to perform whichever task seemed easier. Based on the assumption that effortful tasks were less popular, I took the pooled likelihood that certain tasks were chosen as an estimate of how much effort participants ascribed to the task dimensions. I manipulated movement distance, required speed, dominant vs. non-dominant hand use, body leaning, and momentum. I fitted the choice data with a mathematical that ascribed significant degrees of effort to required speed, non-preferred hand use, and body leaning. The model also made claims about how participants integrated and compared these multi-modal costs. This work demonstrates the promise of the task-choice method for estimating movement costs in reaching tasks and helps establish a rigorous approach to the study of movement-related effort.