ABSTRACT
For actions involving interception and, more generally, for any action requiring tracking of moving projectiles, the performer's essential problem consists of co-ordinating his/her actions with the movements of the projectile. One of the unanswered questions in this domain concerns how humans adapt their actions to accord with the accelerating or decelerating trajectories of projectiles. This question is essential since one can easily observe that, in dynamic sport environments, the velocity of projectiles that need to be intercepted is rarely uniform. For example, in sports such as cricket and tennis, the trajectories of approaching balls are influenced either by decelerations due to air resistance, gravity, surface resistance, or accelerations due to muscular or mechanical impulsion or gravity. One can conceive, as did Rosenbaum (1975), that individuals adapted to the environment are capable of using strategies that allow them to cope with variations in velocity of moving projectiles.
