Author(s): WU, Y., LIU, Y.T., Institution: NATIONAL TAIWAN NORMAL UNIVERSITY, Country: TAIWAN, Abstract-ID: 996

INTRODUCTION:
Three-ball juggling is a complex motor skill requiring two hands to control three balls under specific spatial and temporal constraints. Due to minimal space requirements, it is commonly used as an experimental task in motor learning research. Task constraints influence motor performance and learning, as manipulating equipment or spatial configuration may induce different movement strategies. Previous studies examined how equipment modifications and task space affect learning three-ball juggling [1,3]. Based on these findings, the present study used a comprehensive design to examine whether task constraints facilitate learning. Power and exponential functions were applied to model practice performance and examine learning dynamics.
METHODS:
19 young adults with no prior juggling experience participated. On Day 1, participants completed a pre-test of 10 trials, each up to 30 s; successful catches per trial were recorded. After 2 days of practice, participants averaging 6 catches were excluded, leaving 18. They were randomly assigned to a task-constrained group (task), practicing behind a table with two facing baffles (88 cm × 30 cm), or a control group (con), practicing in open space. Groups practiced from Day 3 to Day 6 for 15 min/day. A post-test identical to the pre-test was administered on Day 7. Sessions were video-recorded, and catches per trial documented. Mean catches at pre- and post-test were analyzed using linear mixed models. Individual learning curves, based on pre-test, daily practice, and post-test, were fitted with a three-parameter power function and an exponential function; fits were compared using the Akaike Information Criterion (AIC).
RESULTS:
The task group averaged 2 catches at pre-test and 10 at post-test, while the control group averaged 2 at pre-test and 19 at post-test. A significant interaction was observed (ps < .001). Post hoc tests showed the control group had higher post-test performance. AIC comparisons indicated the power function better fit learning curves than the exponential function for all participants.
CONCLUSION:
Practicing three-ball juggling under task constraints behind a table did not accelerate learning compared with open-space practice, but also did not hinder it, indicating the skill can be acquired through practice. Learners began achieving 4 catches per trial on Day 2, and mean performance increased to ~5–6 catches by Days 4–5, demonstrating gradual improvement. The three-parameter power function captured performance changes more accurately than the exponential function, consistent with previous findings [2], supporting the multiple-timescale characteristics of learning complex motor skills.
References:
[1] Hautala, R. M. (1988). Perceptual and Motor Skills, 67(2), 563–567.
[2] Haibach, P. S., Daniels, G. L., & Newell, K. M. (2004). Human Movement Science, 23(2), 185–206.
[3] Wu, Y. C., & Liu, Y.-T. (2025b, November 26–28). ASAN2025. J Mot Learn Dev, 13(S1), 34–35.