ABSTRACT
The issue of the uniqueness of the human speech system has long been a concern in psychological research. In this chapter, we have addressed an aspect of this problem by comparing findings on the motor organization of speech with the organization of voluntary movements about the elbow. We have concentrated on the kinematic regularities that accompany changes in the duration of movements. We found that the kinematic patterns for movements of the tongue dorsum were similar to those of voluntary flexion-extension movements about the elbow. In both speech and arm movements a single function described changes in movement duration. Specifically, decreases in duration were accompanied by systematic increases in the ratio of maximum velocity to movement amplitude. The existence of this single function which accommodates a wide range of changes in the duration of individual movements is consistent with the view that both in speech and limb movements, kinematic profiles are equivalent under scalar transformation.
