End-point constraints in aiming movements: Effects of approach angle and speed

Abstract

The present study focuses on two trajectory-formation models of point-to-point aiming movements, viz., the minimum-jerk and the minimum torque-change model. To date, these models do not account for trajectory variations due to self- or externally imposed end-point constraints such as the the direction and velocity with which a target area is approached. To investigate which model accounts best for the effects on movments of such - in many circumstances - realistic end-point constraints, we adjusted both models so that they can generate trajectories of which the final part has a specified direction and speed. The adjusted models yield realistic trajectories with a high curvature near movement completion. The results of an empirical test of the adjusted models show that pointing movements that are constrained with respect to final movement direction and speed can best be described in terms of the general tendency of people to minimize joint-torque changes.