Virtual thrower vs. real goalkeeper: influence of different visual conditions on performance
Résumé
In order to use virtual reality as a sport analysis tool, we need to be sure that an immersed athlete reacts realistically in a virtual environment. This has been validated for a real handball goalkeeper facing a virtual thrower. However we currently ignore which visual variables induce a realistic motor behaviour of the immersed handball goalkeeper. In this study we used virtual reality to dissociate the visual information related to the movements of the player from the visual information related to the trajectory of the ball. Thus, the aim is to evaluate the relative influence of these different visual information sources on the goalkeeper's motor behaviour. We tested 10 handball goalkeepers who had to predict the final position of the virtual ball in the goal when facing: only the throwing action of the attacking player (TA condition), only the resulting ball trajectory (BA condition), and both the throwing action of the attacking player and the resulting ball trajectory (TB condition). Here we show that performance was better in the BA and TB conditions, but contrary to expectations, performance was substantially worse in the TA condition. A significant effect of ball landing zone does, however, suggest that the relative importance between visual information from the player and the ball depends on the targeted zone in the goal. In some cases, body-based cues embedded in the throwing actions may have a minor influence than ball trajectory and vice versa. Kinematics analysis was then combined to these results to determine why such differences occur depending on the ball landing zone and consequently how it can clarify the role different sources of visual information play on the motor behaviour of an athlete immersed in a virtual environment.