Anticipatory judgements associated with vision of an opponent's end-effector: An approach by motion perturbation and spatial occlusion.

This study was aimed at determining how the visual information of an end-effector (racket) and the intermediate extremity (arm) of a tennis server contribute to the receiver's anticipatory judgement of ball direction. In all, 15 experienced tennis players and 15 novice counterparts viewed a spatially occluded computer graphics animation of a tennis serve (no-occlusion, racket-occlusion, and body-occlusion) and made anticipatory judgements of ball direction on a visual analogue scale (VAS). The patterns of the serve motions were generated by a simulation technique that computationally perturbs the rotation speed of the selected racket-arm joint (forearm pronation and elbow extension) on a captured serve motion. The results suggested that the anticipatory judgements were monotonically attuned with the perturbation rate of the forearm pronation speed excepting under the conditions of the racket-occlusion model. Although such attunements were not observed in the elbow perturbation conditions, the results of correlation analysis indicated that the residual information in the spatially occluded models had a similar effect to the no-occlusion model within the individual experienced participants. The findings support the notion that end-effector (racket) provides deterministic cues for anticipation, as well as imply that players are able to benefit from the relative motion of an intermediate extremity (elbow extension).

Perceptual response and information pick-up strategies within a family of sports.

The purpose of this study was to determine whether and how the perceptual response of athletes differed depending on their sporting expertise. This was achieved by comparing the responses of tennis and soft tennis players. Twelve experienced tennis players and 12 experienced soft tennis players viewed computer graphic serve motions simulated by a motion perturbation technique, and then scaled their anticipatory judgments regarding the direction, speed, and spin of the ball on a visual analogue scale. Experiment 1 evaluated the player's judgments in response to test motions rendered with a complete polygon model. The results revealed significantly different anticipatory judgments between the player groups when an elbow rotation perturbation was applied to the test serve motion. Experiment 2 used spatially occluded models in order to investigate the effectiveness of local information in making anticipatory judgments. The results suggested that the isolation of visual information had less effect on the judgment of the tennis players than on that of the soft tennis players. In conclusion, the domain of sporting expertise, including those of closely related sports, cannot only differentiate the anticipatory judgment of a ball's future flight path, but also affect the utilization strategy for the local kinematic information.