Task dynamic model of gestural control and coordination (Developed at Haskins Laboratories (Saltzman & Munhall, 1989).

• Tasks

  Each gesture has task or goal to produce a particular constriction within the vocal tract.

  Constrictions are defined using vocal tract variables (TVs).

  Each gesture is assigned one (or a pair of) tract variable specifications.

  Specification is fixed (invariant) for a given gesture is context-independent.

• Dynamics

  Constriction-formation is modeled by spring-like (elastic) control.

  Just as springs always return to their rest position, constricting device will return to its tract-variable specification (rest position is "tuned" to TV specification).

  Tract variable specification is fixed over the time-span during a gestural constriction is formed.

• Coordinative Stuctures: synergies

  Combination of articulators used to achieve constriction is flexible and context-dependent.

  Articulator ensemble for a gesture is a coordinative structure.

  Articulator-level dynamic controls evolve during the constriction span of a gesture.

Evidence for coordinative structures ?