Abstract
Purpose: Previous studies have suggested that the extrapolation of an occluded target movement is influenced by the target velocity of the preceding trial, (Lyon and Waag, 1995, de Lussanet et al, 2001, Makin et al, 2008) and the overall mean velocity of the target (Brouwer et al., 2002, Makin et al, 2009). However, those studies may fail to isolate the effect of the preceding trial's velocity from the effect of overall mean velocity, and vice versa. We examined the significance of the two effects. Method: In a virtual environment, a moving target disappeared behind an occluder and subjects hit the target at the impact zone when the target is supposed to be in the zone had it moved with a constant velocity. Seven velocities (6 deg/s to 18 deg/s) and four occluded distances (6 deg to 18 deg) were used and the exposure duration of the target was fixed at 800ms across all conditions. Results: A model was developed to predict the hitting time which is the duration from the moment of the target disappearance to the moment of a subject's hitting on the impact zone. Velocities of the first preceding trial, the second preceding trial, and the overall mean velocity, and the mean hitting time were considered as possible factors influencing the performance on the current trial. A cross validation technique was used to select a model. The model with the best fit includes the first preceding velocity and the second preceding velocity terms but does not include the overall mean velocity and the overall mean hitting time terms. Conclusion: Results suggest that extrapolation of target movement is influenced by the preceding velocities rather than by the overall mean velocity.