Coordination.

The Russian physiologist Bernstein (1967) defined coordination as a problem of mastering the very many degrees of freedom involved in a particular movement--of reducing the number of independent variables to be controlled. The initial theorizing and experimentation on "Bernstein's problem" was conducted largely in terms of how a device of very many independent variables might be regulated without ascribing excessive responsibility to an executive subsystem. A second round of theory and research on Bernstein's problem is now under way. This second round is motivated by similarities between coordination and physical processes in which multiple components become collectively self-organized; it is directed at an explanation of coordination in terms of very general laws and principles. The major achievements of the first round of efforts to address Bernstein's problem are summarized, and six examples of the theory and research typifying the second round are presented.