title: Stopping is not an option: the evolution of unstoppable motion elements (primitives).
abstract: Stopping performance is known to depend on low-level motion features, such as movement velocity. It is not known, however, whether it is also subject to high-level motion constraints. Here, we report results of 15 subjects instructed to connect four target points depicted on a digitizing tablet and stop "as rapidly as possible" upon hearing a "stop" cue (tone). Four subjects connected target points with straight paths, whereas 11 subjects generated movements corresponding to coarticulation between adjacent movement components. For the noncoarticulating and coarticulating subjects, stopping performance was not correlated or only weakly correlated with motion velocity, respectively. The generation of a straight, point-to-point movement or a smooth, curved trajectory was not disturbed by the occurrence of a stop cue. Overall, the results indicate that stopping performance is subject to high-level motion constraints, such as the completion of a geometrical plan, and that globally planned movements, once started, must run to completion, providing evidence for the definition of a motion primitive as an unstoppable motion element.
authors.affiliation: Faculty of Electrical, Electronics and Communication Engineering, Holon Institute of Technology, Holon, Israel; and ronens@hit.ac.il.
authors.forename: Ronen
authors.initials: R
authors.lastname: Sosnik
authors.affiliation: Faculty of Electrical, Electronics and Communication Engineering, Holon Institute of Technology, Holon, Israel; and.
authors.forename: Eliyahu
authors.initials: E
authors.lastname: Chaim
authors.affiliation: Department of Applied Math and Computer Science, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Tamar
authors.initials: T
authors.lastname: Flash
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001307:Auditory Perception / Q000502:physiology; D001696:Biomechanical Phenomena; D001921:Brain / Q000502:physiology*; D003463:Cues; D004569:Electroencephalography; D005071:Evoked Potentials; D006801:Humans; D008875:Middle Aged; D008954:Models, Biological; D009038:Motion; D009043:Motor Activity / Q000502:physiology*; D055815:Young Adult
keywords: coarticulation; motion primitives; point of no return; scribbling movements