Models of human arm trajectory control

The author assesses the validity of three models dealing with human arm trajectory control by evaluating their success in accounting for the kinematic characteristics of planar horizontal unconstrained point-to-point arm trajectories. These models are concerned with two significant issues. Namely, in what coordinate frame(s) are movements internally represented by the brain and, how intention is translated into action. The results support the notion that a desired trajectory in extrapersonal coordinates is first planned and is then realized by motor commands which take advantage of the viscoelastic properties of muscles.<>