The power of illusion can help learn new moves

Researchers at Tokyo Metropolitan University have shown that visual aids that create the illusion of movement, such as a screen placed in front of the hand showing hand movement, can improve motor performance and early stages of learning engine. Compared to third-person observation of movements, functional near-infrared spectroscopy data also showed greater changes in brain activity in regions associated with motor learning.

Findings like this could inform new treatment strategies for hemiplegic stroke patients. The study is published in the journal Scientific reports.

The visual-motor illusion (VMI) is the curious illusion of watching your body move even though it is still. Imagine having a tablet screen placed in front of your hand. Your hand is hidden behind the tablet and it does not move. Now imagine the screen playing a video of your hand moving; your eyes tell you that your hand is moving, but it’s not moving at all.

This troubling situation is instantly resolved if you place the screen elsewhere; looking at the screen now simply involves action observation (AO). Previous work has already shown that VMI and AO lead to different responses in the brain, but the broader implications of VMI remain unclear.

Now, a team of scientists led by Assistant Professor Katsuya Sakai from Tokyo Metropolitan University has shown that VMI can improve motor performance and motor learning at an early stage. The volunteers were given a specific task: rolling two metal balls in one hand.

After some initial testing, a visual aid was used showing hands performing this exact action. One group had the visual aid placed in front of their hand to invoke VMI, while another group simply watched the same video normally. Performance could be measured by the number of complete rolls handled by people.

Although both groups showed improvement, the VMI group showed greater improvement than the AO group, immediately after showing the video to the volunteers and one hour afterward. This not only shows an improvement in performance, but also emphasizes that early learning has also improved, i.e. the changes can persist.

To understand what’s happening in the brain, the team used functional near-infrared spectroscopy, a non-invasive technique that tracks activity in specific parts of the brain using external probes. They were able to discover key differences between AO and VMI volunteers in parts of the brain associated with learning new movements.

Importantly, these changes persisted for an hour after the visual stimuli, consistent with what they saw while performing the task. This was also consistent with the group’s previous findings showing how connectivity in parts of the brain responsible for motor execution was improved by VMI.

The team notes that there is still much work to be done. For example, these results come from a study on healthy individuals, and there is not yet an assessment of medium and long-term motor performance. However, the lessons learned from this study highlight a unique strategy to improve motor performance and learning, which could one day be applied to the rehabilitation of hemiplegic stroke patients and guide the development of new treatments.