Changes in Motor Performance When Throwing a Ball With and Without Visual Feedback

Mentor: Dr. John RieserThis study explored the roles that vision and proprioception play in learning while throw a ball repeatedly to a fixed location. In two experiments, participants threw a baseball to a target 12 meters away while wearing sound-cancelling headphones to block out auditory feedback. In Experiment 1 participants could freely see the target, but as soon as the ball left their hands, their vision of the ball’s flight and landing was occluded by liquid crystal goggles. Measurements of the ball’s distance of travel along the ground and variability of landing locations were recorded to observe participants’ throwing accuracy and consistency across 100 trials. Results show that participants almost always threw short. The throws improved in consistency for the first half of the trials, showing that people can use proprioceptive feedback to improve the consistency of their motor performance. Experiment 2 was similar to Experiment1, except half of the participants could see the ball’s flight trajectory. Both groups started out throwing short of the target, but the group with visual feedback threw increasingly closer to the target across the 30 repeated trials. Both groups improved their throwing consistency. Kinematic analysis showed that people depended on the ball’s initial velocity rather than the release angle to regulate the distance the ball traveled.Vanderbilt UniversityPsychological SciencesArts & SciencesThesis completed in partial fulfillment of the requirements of the Honors Program in Psychological Science