Abstract: Objective: To examine whether and when a priori information (opponent's action preference) would influence goalkeepers' anticipatory performance and the critical time points. Methods: Twenty soccer goalkeepers (experts) and twenty-four college students (controls) were recruited for the study. They were required to predict the direction of penalty kicks before and after a training intervention from the perspective of goalkeepers. During the training phase, half of the participants in each group were provided a priori information that the kicker had a strong preference to kick to one particular direction, while the other half viewed kickers who kicked equally to all directions. Using the temporal occlusion paradigm, the video materials were occluded at three-time points relative to ball release. Results: The results showed that exposure to incongruent a priori information with the kinematic information of kickers significantly decreased performance only in the controls (P ≤ 0.007). It was further found that a priori information acquired in the training intervention could significantly improve the anticipatory performance for experts in the earliest occlusion condition (P=0.001), but not in the moderate and latest conditions. Conclusion: These findings provide further evidence of the influence of a priori information on action anticipation in goalkeepers and suggest its occurrence in the earliest course of a kicker's unfolding action (100 ms prior to foot-ball-contact), while controls depend more on a priori information regardless of the amount of kinematic information. The results enrich the theoretical research of expert advantage and provide some enlightenment for sports practice.

Key words: soccer goalkeepers, action anticipation, a priori information, current kinematic information, temporal occlusion