Coordination between hand and trunk movements in a Fitts' Law task

Fuwen Cai, Purdue University

Abstract

It has been shown that limb movements are coupled in space and time in a bimanual Fitts' task. The present study was designed to examine whether coordination of hand and trunk share some sets of coordinative principles with bimanual coordination. Participants (n = 28) were required to perform a Fitts' task with the dominant hand and a Fitts' task with the trunk. These tasks were performed separately or together. The task required moving the trunk, the dominant hand or both, such that the cursor/cursors on a computer screen was/were moved from the starting position/positions to the designated target/targets as fast and as accurately as possible. When the hand and the trunk moved in the same direction, hand movement and trunk movement were initiated and executed in a synchronized fashion, and the velocity was coupled. In contrast, when the hand and the trunk moved in the opposite directions, hand movement and trunk movement were not synchronized and the velocity was not coupled, as though they moved independently. The distinctions were further confirmed when the results were compared across different combinations of movement directions. Hand movement and trunk movement were more synchronized and the velocity was more coupled when they moved in the same direction than when they moved in the opposite directions. In addition, hand movement and trunk movement were initiated sooner and executed faster when they moved in the same direction than when they moved in the opposite directions. Therefore, the coordination between hand and trunk when they moved in the same direction showed the same coordinative patterns as the bimanual coordination, but not when they moved in the opposite directions. It is argued that the interaction between biomechanical and task constraints played an important role in determining optimal coordinative patterns. In conclusion, the coordinative patterns are not determined solely by the muscular skeletal structure involved in the coordination, but are determined by the interaction of biomechanical constraints and task constraints imposed on the action of the effectors. The central nervous system controls the formation of synergies to optimize the coordinative patterns also depending on the constraints. These findings support the idea that coordination is the result of the constraints imposed on the action of the effectors.

Degree

Ph.D.

Advisors

Zelaznik, Purdue University.

Subject Area

Kinesiology

COinS