PLANNING OF ACTION SEQUENCES

This paper reports an experiment on the advance planning of actions. T welve subjects grasped an 8-sided object, and performed a sequence of movements involving juxtaposing a designated face of the object with a designated target. The location of each finger of the right hand on t he faces of the 8-sided object was recorded. Results showed that the g rip pattern differed significantly from a case where subjects were ask ed simply to grasp the 8-sided object, without moving it. Further, com parison of sequences of moves involving different target positions sho wed that subjects did chose grip patterns based on the specific moves they were asked to make. These adjustments were generally more common when the critical item occurred earlier in a sequence than when it occ urred later, suggesting a gradient of advance planning comparable to t he serial position effect in memory tasks. Further, the grip adjustmen ts observed consisted primarily of reconfigurations of the hand, invol ving changing the point of contact on the object of a subset of finger s, rather than rotations of the whole hand with respect to the object. (C) 1998 Elsevier Science B.V. All rights reserved.