ABSTRACT
This chapter reports three experiments that examined the interrelations of temporal planning and effector specification for trains of movements through reaction time procedures. More specifically, the question addressed was whether sequential plan and effector are selected one at a time and, if so, whether order of selection is fixed. In all experiments, the task of the subjects consisted of making one of four finger-tapping sequences that differed in the location of an emphasized element and hand employed. Subjects could receive advance information regarding one or another of these attributes either long in-advance (> 2000 ms) or briefly-in-advance (0, 30, 60, 90 ms) of the reaction signal that specified the remaining response attribute. The lack of consistent headstart effect except for advance hand information when initial emphasis was known argues against serial parameterization of the hypothesized "sequential plan" and "effector" dimensions, but suggests serial programming of the constituents of the upcoming movement sequence. A serial-programs model is presented in which specification of effector is integrated with specification of its mode of action to program the initial response. Foreknowledge of the sequential plan facilitates the programming of the sequence elements, but such a plan can be flexibly updated with new information when programming or execution is already in progress.
