Parallel processing is often considered to be synonymous with biological computation, but a great deal of evidence points to serial computation being used by animals to solve specific types of problems. In particular, the observation of movement intermittency (fluctuations in limb kinematic variables that cannot be explained by low-level dynamics of the system) seems to imply a serial temporal segmentation strategy in the planning of arm movements. This paper discusses prior observations of movement intermittency in different task contexts, possible theoretical and physiological origins of the phenomenon, and implications for human movement strategies.