Factors Contributing to Efficiency of Arm Movements Revealed through Directional Biases

Arizona State University, Scottsdale AZ

Investigators

Abstract

Daily activities often require fast and accurate arm movements that can be performed for a long period without fatigue. Understanding which strategies result in proficiency of performance, and why, is extremely important for optimizing the efficiency of daily activities, ergonomic designs, and design of prosthetic devices. The present project uses an innovative approach that elaborates on directional biases in arm movements. Directional biases mean that arm movements performed in different directions relative to the body vary in terms of accuracy, speed, and the amount of muscle effort expended. Thus, it is possible that an increase in performance efficiency can be achieved by selecting optimal movement directions relative to the body, while moving in a variety of directions in space might be best achieved by adjusting the position of the body. Directional biases during arm movements and the conditions that influence them are explored using a novel, free-stroke drawing task in which subjects perform arm movements in as many different directions as possible in the horizontal plane. The effects of directional biases under the different movement conditions will be studied, as well as factors that may cause the emergence of directional biases. The project will generate important knowledge with respect to control strategies that make arm movements economical, accurate, fast, and resistant to fatigue. This knowledge may create a basis for a wide range of ergonomic and clinical applications, such as minimization of fatigue, prevention of injuries, work cost decreases, and development of advanced prosthetic devices and anthropomorphic robots.