Time course of movement planning: Selection of handgrips for object manipulation.

Abstract

A goal of research on the cognitive control of movement is to determine how movements are chosen when many movements are possible. We addressed this issue by studying how subjects reached for a bar to be moved as quickly as possible from a home location to a target location. Ss generally grabbed the bar in a way that afforded a comfortable posture at the target location (the end-state comfort effect) and with the thumb toward the end of the bar that would be aligned with the target (the thumb-toward bias). The data suggested that subjects chose handgrips by retrieving instances of previous reaches, not by carrying out computations that treated candidate reaches as new behavioral events.

What is the point of motor planning?

“…Similar effects have been obtained for reaction times to initiate hand movements that end with different orientations (Rosenbaum, Vaughan, Barnes, & Jorgensen, 1992). In the latter study, the ending orientations were determined by the subjects and were not due to differences in what the subjects saw prior to acting.…”

Minimum Principles in Motor Control

“…Additional support for this hypothesis comes from a number of studies by Rosenbaum and his collaborators Rosenbaum, Vaughan, Marchak, Barnes, 6 Slotta, 1990;Rosenbaum, Vaughan, Barnes, 6 Jorgensen, 1992;Rosenbaum et al, 1993). The general type of task investigated in these studies required a subject to grasp an object and then transport it to a new location or to place it in a new orientation.…”

Planning and Representing Intentional Action

“…For instance, in manual grasping, the size of the to-be-grasped object is commonly reflected in the shape of the hand long before the actual contact takes place [23,24]; to-be-moved objects are grasped in such a way that hand comfort at the end of the move is optimized [9,25,26]; phonemes are spoken differently depending on the phonemes that follow; and errors in speech [27,28] and typewriting [13,29] are often anticipatory in nature, i.e., consist in prematurely producing letters, syllables, and words from the remaining part of the word or sentence.…”