Keynote Address

Changing Degrees of Freedom in Motor Learning and Control

Prof. Karl M. Newell

Department of Kinesiology,
The Pennsylvania State University, College Park, USA

Bernstein (1967) viewed the coordination of movement as the process of mastering redundant degrees of freedom of the moving organ or the organization of the control of the motor apparatus. His views on the degrees of freedom problem in motor learning and control have been and still are very influential in regard to both theory and experiment. Paradoxically though, there has been very little direct study of the degrees of freedom issue, in spite of the focus that Bernstein gave it and the prominence that others have given to this issue, such as in the early theorizing of the ecological approach to perception and action.

In this talk I will revisit the essence of the Bernstein position on degrees of freedom in motor learning and control, paying particular attention to the related notions of multiple and redundant degrees of freedom. From this background, the central issue to be addressed will be the change in degrees of freedom that accompanies motor learning and development. In particular, I will discuss the related propositions that: (1) motor skill learning involves the regulation of an increased number of degrees of freedom; and (2) that aging is associated with a loss of complexity or a decrease in the number of independent degrees of freedom that can be regulated. A distinction will be advanced between the general capacity of the system to organize degrees of freedom in action and the particular change in the solution for coordination that is required in a given motor skill context. The direction of change in number of degrees of freedom regulated in the performance of a given task is dependent on the particular confluence of constraints arising from the interaction of the organism, environment, and task.