PERCEPTION-ACTION COUPLING IN HITTING AND CATCHING

This paper addresses the contribution that recent studies of hitting a nd catching have made to the understanding of the coordination between actors and their environment from an ecological psychological perspec tive. Experiments with top players in table tennis demonstrated that t he skilful execution of an attacking forehand drive is governed by a f inely tuned perception (time-to-contact) - action (acceleration) coupl ing. In the first reported catching experiment a directly manipulation of the optical expansion pattern of the approaching hall was carried out by using a deflating ball. Adjustments to the aperture of the hand in response to the different ball sizes - especially the adjustments of the hand to the deflating ball - point not only to a finely attuned perception-action coupling, but strongly indicate that such coupling is based on time-to-contact information. Learning is considered to be the direction of attention, with attention refering to the control of information detection. Novice table tennis players learning such a ski ll reveal changes not so much in the movement patterns produced, but r ather in the attunement of their actions to specific visual informatio n sources. Learning to catch a hall under conditions in which only the moving ball was visible resulted in a better performance under full l ight conditions than did training under such conditions, because the c atchers are attending to information sources specifying the spatiotemp oral information of the ball, implying that the learning process can b e viewed as the establishment of a skill-specific perception-action co upling.