Materials and methods
Participants randomly performed the kinesthetic illusion condition with VMI (VMI group) or the action observation condition (AO group, 18 participants each). Each condition was performed for 20 min on the left upper limb. Pre, Post1 (immediately), and Post2 (after one hour) for each condition, the ball-rotation task was performed, and brain activity was measured during the ball-rotation task using fNIRS (Fig. Protocol and measurement phase. Each condition was conducted for 20 min. Pre, Post1 (immediately), and Post2 (1 h later) each condition, the ball rotation task was measured using the block design, and the brain activity was measured during the ball rotation task using the functional near-infrared spectroscopy. The degree of kinesthetic illusion, sense of body ownership, and sense of agency were measured immediately after each condition.