Weighted combination of size and disparity: a computational model for timing a ball catch

How do we time hand closure to catch a ball? Binocular disparity and optica l looming provide two sources of information about an object's motion in de pth, but the relative effectiveness of the two cues depends on ball size. B ased on results from a virtual reality ball-catching task, we derive a simp le model that uses both cues. The model is sensitive to the relative effect iveness of size and disparity and implicitly switches its response to the c ue that specifies the earliest arrival and away from a cue that is lost or below threshold. We demonstrate the model's robustness by predicting the re sponse of participants to some very unusual ball trajectories in a virtual reality task.