Analysis of juggling data: Landmark and continuous registration of juggling trajectories

Abstract

This paper focuses on the two one-dimensional summaries of the three-dimensional juggling data: tangential velocity and tangential acceleration. These are used jointly to define the beginnings and endings of the 123 cycles in the data divided unevenly over ten trials. Two levels of registration were used. The first was a landmark registration of each trial to a periodic image of itself with the period fixed at 712 milliseconds. The 123 tangential velocity cycles were then subjected to a continuous registration over this fixed cycle length. The amounts of across-trial and within-cycle phase variation, respectively, were surprisingly small, indicating tight neural control over the behavior. Within-cycle phase variation was primarily due to variation in the trajectories of the ball between throw and catch.