Practice-dependent changes in body representation but not in reaching distance following virtual tool-use

Previous research has shown that tool-use can modify neural representations of our body and the space surrounding us. Furthermore, virtual tools can become incorporated into the user's body representation after training. However, the extent to which such changes depend on the amount of sensorimotor experience remains unclear. In the present study, we investigated whether different amounts of virtual tool-use training (30, 60, 90 and 120 trials) influence body and action-oriented spatial representations. Participants completed a tactile distance judgment (TDJ) task, indexing body representation; and a reaching distance estimation (RDE) task, indexing perceived actionable space, before and after virtual tool-use training. Virtual tool-use produced an overall decrease in TDJ responses, indicating plastic changes in the forearm tactile distance perception. Although the magnitude of change varied across training conditions, the strongest and most reliable evidence for TDJ change emerged following 120 trials of practice, suggesting that extended sensorimotor experience may be required for stable modifications of body representations. In contrast, RDE changed modestly from pre-test to post-test but did not vary systematically with training duration, suggesting that perceived reaching distance may adapt more rapidly and with less dependence on additional practice. Arm length was a significant predictor of RDE error, indicating that stable anatomical constraints continue to influence reachability judgments despite tool-use experience. Together, these findings suggest a dissociation between body representation and perceived reaching distance, with each exhibiting distinct temporal dynamics following tool-use training. More broadly, the results demonstrate that virtual tool-use can induce changes that transfer to subsequent physical assessment, highlighting virtual environments as a valuable framework for investigating body representation plasticity and tool embodiment.