Effects of Practice on Speed and Accuracy in Juggling.

Many motor skills in daily activities require hand-eye coordination, the performance of which can be measured by using speed or accuracy. Juggling provides a useful model for studying changes in speed and accuracy during skill acquisition. Seventy-four participants practiced 3-ball cascade juggling for 12 min each day for 18 days. On each day, we recorded the number of catches and the duration of each trial by the end of practice. Performance was evaluated using the number of catches and trial duration, from which accuracy was quantified as the probability of successfully catching a tennis ball and speed was quantified as juggling frequency. Over 18 days, participants improved accuracy from 0.67 to 0.91 in a decelerating pattern. Males were 16% more accurate than females on each day of practice. After adjusting for hand size, both genders showed similar accuracy. Juggling speed increased from 1.2 to 2.3 Hz, with no significant gender differences in 15 out of 18 days. These findings provide a probabilistic framework for characterizing skill acquisition in continuous motor tasks with cyclic and repetitive movement patterns and may help identify sensory and motor deficits in the upper extremities.