Rules for Posture Selection

Previous studies on sequential effects of human grasping behaviour were restricted to binary grasp type selection. We asked whether two established motor control strategies, the end-state comfort effect and the hysteresis effect, would hold for sequential motor tasks with continuous solutions. To this end, participants were tested in a sequential (predictable) and a randomised (non-predictable) perceptual-motor task, which offered a continuous range of posture solutions for each movement trial. Both the end-state comfort effect and the hysteresis effect were reproduced under predictable, continuous conditions, but only the end-state comfort effect was present under non-predictable conditions. Experimental results further revealed a work range restriction effect, which was reproduced for the dominant and the non-dominant hand. This chapter is a revised version of Schütz, C., Weigelt, M., Odekerken, D., KleinSoetebier, T., and Schack, T. (2011). Motor control strategies in a continuous task space. Motor Control, 15 (3), 321-341.