ABSTRACT
In this chapter we address problems pertaining to the current or ongoing control of action—problems that, fundamentally, rest with understanding how perception and production are linked in biological activities. There have been a number of quite recent treatments, both behavioral and physiological, of motor control of simple limb movements performed in relatively uncomplicated environments. Rather than review that material again (see, e.g., Keele, 1981; Kelso, 1982a; Schmidt, 1982, for largely behavioral treatments; and, e.g., Houk & Rymer, 1981; Stein, 1982, for a largely neurophysiological-engineering analysis), we try to expand the horizons of “control” a bit in this chapter—a larger sweep of the brush, as it were (see also Reed, 1982). To a certain extent, we consider goal-directed activities like reaching for a cup, driving a car, climbing stairs—activities that involve very large numbers of degrees of freedom on both the motor and perceptual side of things. Thus, on the performance side were one to count, say, the number of neurons, neuronal connections, and muscle fibers involved (even in so-called simple actions like moving a finger), the result would be a large number. Likewise, on the perception side the light rays to the eye, the retinal mosaic, and the neural processing structures involved amass into a problem of huge dimensionality. Yet somehow—in spite of the large dimensionality on both sides of the coin (or perhaps because of it)—control is possible. Some-how, this high dimensionality gets compressed, as it were, into lower dimensional control. How this is realized, of course, is the challenge faced, not only by students of perception and action, but in other realms of science as well.
