Since World War II, interest in manual control as a design problem has steadily increased. Perhaps no area of man-machine research has produced more scientific literature. However, the rather diverse assortment of manual control equipment in operation today is strongly suggestive of a general failure to utilize empirical findings during the design process. That is, many designs appear to be based onrationale which might be best described as "intuition". Moreover, seldom are parametric studies conducted to determine whether a new design is any better, or worse, than existing equipment. Thus, evaluations of such designs are not, in effect, evaluations at all.