Validity of Low-Dimensional Representation of Whole-Body Movements

Research on impression evaluation from whole-body movements has traditionally focused on the relationships between emotional perception or aesthetic evaluation and movement patterns characterized by local kinematic features and inter-limb coordination. However, because observers perceive the entire body simultaneously when evaluating emotions or aesthetics in real-world viewing situations, impressions derived from whole-body movements should also be investigated. This requires a low-dimensional representation that summarizes whole-body information in an interpretable manner. In the present study, we evaluated whether the state space generated by multidimensional scaling (MDS) provides a valid representation for summarizing whole-body movement. Specifically, using exercises from Radio Calisthenics No. 1, we examined whether distances between points in the MDS state space primarily reflected exercise category rather than individual differences. The results showed that distances in the state space reflected exercise category more strongly than performer identity, suggesting that MDS captures similarities among postures of the same exercise. However, the patterns of distances between conditions varied across exercise categories. These findings suggest that MDS-based state-space representations provide a valid and interpretable approach for summarizing whole-body movements. Nevertheless, further validation using a wider variety of whole-body movements and a more diverse participant population is required.