Using vocalization to increase success rate in ball games — Shizuoka University reveals how the brain differentiates multiple types of ball

A research group including Graduate Student Shu Natsume at Shizuoka University's Graduate School of Integrated Science and Technology, Professor Makoto Miyazaki at Shizuoka University's Faculty of Informatics, and Professor Neil W. Roach at the University of Nottingham (UK), has announced their research findings demonstrating that the use of concomitant motor responses such as vocalization can improve the accuracy of movement timing. In an experiment on a timing task, they confirmed that the group of participants who used concomitant motor responses according to the condition was able to efficiently distinguish and learn short prior (fast pitch) and long prior (slow pitch) distributions. The findings are expected to contribute to the development of methods for improving sports skills. The results were published in the January 29 issue of Proceeding of the Royal Society B: Biological Sciences, a journal published by the Royal Society.

Athletes often vocalize in response to movement during sports competitions. Although vocalizations accompanying motor responses have been reported to improve exerted muscle strength, they were not considered to improve the accuracy of motor responses. Previously, the research group demonstrated that the brain learns the statistical distribution (mean and variance) of a target in a timing task and improves task success rates through Bayesian estimation. To apply this mechanism in everyday environments, the brain must be able to distinguish and learn various statistical distributions. For example, in baseball, hitting a slow pitch requires responding based on a statistical distribution different from that used for hitting a fast pitch. Last year, the research group found that different prior distributions for timing can be learned using different body parts—for instance, the hands for slow targets and the feet for fast targets. However, for skill improvement, it is generally preferable to refine abilities using the same body part.

In this study, the research group focused on concomitant motor responses. They experimentally tested if skills can be improved by learning prior distributions using a "concomitant motor response" to one of the targets in a timing task. A total of 64 healthy men and women (aged 18-25 years) participated in Experiments 1 and 2, in which 32 each used different concomitant motor responses. To acquire prior distributions of timing, two circles (〇; side by side) on the display were illuminated twice in succession. After the first (S1) and second (S2) illuminations, participants were instructed to respond to the third illumination (S3) by tapping their dominant index finger, ensuring that the interval between S2 and their motor response to S3 matched the interval between S1 and S2. A circle on the dominant-hand side was illuminated, or both circles were illuminated simultaneously. The time interval between illuminations followed either a short prior distribution (mean ≈ 0.7 seconds, ranging from 0.4 to 1.0 seconds) or a long prior distribution (mean ≈ 1.4 seconds, ranging from 1.0 to 1.7 seconds). Each participant completed 640 trials, with illumination intervals randomly selected from the short and long prior distributions, ensuring both distributions occurred at equal frequencies for all participants.

In Experiment 1, comparisons were made between participants who responded only with their dominant hand and those who responded simultaneously with both hands when both circles were illuminated. In Experiment 2, comparisons were made between participants who responded only with their dominant hand and those who vocalized "Ba" while responding with their dominant hand when "Ba" was displayed in the circle on the non-dominant hand side.

The results of the analysis of the latter 320 trials showed that the group of participants who responded only with the dominant hand could not learn the prior distributions adequately in both Experiments 1 and 2. In contrast, the group of participants who additionally used a concomitant motor response could clearly distinguish and learn the short and long prior distributions. For example, in the practice of receiving, tennis players may be able to receive balls at the right timing according to the type of ball by selecting a specific type of ball and using concomitant motor responses, such as gripping with the non-dominant hand or shouting, in conjunction with the hitting motion.

Miyazaki spoke of his vision, "Moving forward, we would like to use the VR system to verify whether this effect can be applied to sports movements and explore brain regions related to this effect."

Journal Information
Publication: Proceeding of the Royal Society B: Biological Sciences
Title: Concomitant motor responses facilitate the acquisition of multiple prior distributions in human coincidence timing
DOI: 10.1098/rspb.2024.2438