Virtual environments have been widely utilized in motor neuroscience and rehabilitation as they afford tight control of sensorimotor conditions and readily afford visual and haptic manipulations. However, typically studies have only examined performance in the virtual testbeds, without asking how performance in the virtual environment compares to behavior in the real world. To test that, this study compared throwing in a virtual and real set-up where the task parameters were precisely matched. Even though the virtual task only required a single-joint arm movement, similar to many simplified movement assays in motor neuroscience, throwing accuracy and precision was significantly better in the real task; only after three days did the performance reach same levels. To gain more insight into the structure of the learning process, movement variability was decomposed into deterministic and stochastic contributions to distinct stages of learning by using the TNC method: Tolerance was optimized first and was higher in the virtual environment, suggesting that more familiarization and exploration is needed in the virtual task. Covariation and noise showed far fewer and only contributes late in the real task, indicating that subjects reached the stage of fine-tuning of variability only in the real task. These results showed that while the tasks were precisely matched, the simplified movements in the virtual environment required more practice to be successful. These findings resonate with the reported problems in transfer of therapeutic benefits from virtual to real environments and alert that the use of virtual environments in research and rehabilitation needs more caution.
Back to Reality: Differences in Learning Strategy in a Simplified Virtual and a Real Throwing Task