Object and Target Size Interactions in Placement Tasks

Abstract

Hand movement trajectories and coordination are influenced by task characteristics. This study investigated hand kinematics in the performance of placement tasks using cylindrical objects. Performance was evaluated both in terms of movement time and the composition of multiple phases that make up the movement. Object size, target size, and movement distance were varied. For a given movement distance, movement time was the same for all objects when the difference between the target and object diameter was constant. Thus total movement time depended neither on the object size nor on the target width, but on the relationship between object and target width. However, for a constant object-target size relationship, closed-loop feedback corrections began earlier for smaller objects than for larger objects. Peak velocities of movements decreased with increase in object size.