Tilted trials: Assessing performance with varying angle perturbations in visuomotor adaptation task

Objectives: This study examined how varying angular perturbations in a visuomotor adaptation task (VMAT) influence implicit and explicit motor learning. The goal was to assess whether implicit adaptation can compensate for limitations in explicit learning, particularly in the context of neurological rehabilitation. The study was designed to map the implicit and explicit learning processes in response to a specific perturbation angle in a VMAT using mean directional errors and adaptation as outcome variables. Materials and Methods: Participants performed reaching tasks under visuomotor rotations of different angles (30°, 45° and 60°), presented in block sequences. Performance was measured using mean directional errors and adaptation levels, reaction time (RT) and movement time (MT). The design allowed for the distinction between implicit and explicit learning based on changes in performance across blocks. Results: As expected deterioration in performance was observed (as indicated by mean directional errors) on exposure to altered perturbation during each block. Participants struggled to adapt for smaller angle (the RT and MT failed to improve across block), as they used sensory feedback rather than relying on implicit strategy. Partial adaptation was observed until block 2 for sequences with smaller angles presented together. Small angles (30° and 45°) showed no improvement, indicating that magnitude of movement is critical for precise motor control. Conclusion: This approach is especially important for tasks that require explicit knowledge of subsequent actions. The study highlights the importance of visual representations of hand position in motor learning, and its findings could be applied to specialized rehabilitation training.