Perceptual versus motor awareness of explicit contributions to visuomotor adaptation

The human brain is a master of adjustment. When you learn to drive a car with a different steering ratio, or when you put on a pair of glasses that shift your view of the world, your body eventually learns to compensate. This ability, known as adaptation, allows us to keep our movements accurate even when the rules of our environment change. But a lingering question in the study of how we move is whether we are consciously aware of these adjustments as they happen. Do we know, in our minds, that we are correcting for a shift? Or does the correction happen automatically, below the level of our conscious thought, while our mind remains unaware of the specific changes our muscles are making? Understanding the difference between what we feel is happening and what our body is actually doing helps scientists map the separate systems that control our perception and our actions.

In a recent experiment, researchers set out to test this gap between feeling and doing. They asked participants to reach for targets on a screen while wearing equipment that altered the visual feedback of their hand movements. Specifically, the researchers rotated the cursor representing the hand's position on the screen, forcing the participants to adjust their reaching angle to hit the target. The study involved two groups of people: one group faced a large rotation of 50 degrees, while the other faced a smaller rotation of 30 degrees. After the participants adapted to these shifts, the researchers used two different methods to measure their awareness. First, they asked the participants to report what they perceived about the rotation, essentially asking, "What did you see?" Second, they used a specific testing technique to measure motor awareness, which determined how much of the adjustment the participants could consciously control when asked to reach without the visual aid.

The results showed a clear split depending on the size of the rotation. For the group facing the large 50-degree shift, the participants' reported perception of the rotation matched their motor awareness. They knew they were seeing a shift, and their bodies showed they knew how to correct for it; the two types of awareness were linked and moved together. However, the story changed for the group facing the smaller 30-degree shift. These participants reported that they were aware of the visual rotation, yet their motor awareness was significantly lower. When tested on their ability to consciously control the correction in their reaching, they showed far less awareness than they claimed to have. Furthermore, for this smaller shift, there was no meaningful connection between what they said they saw and how their motor system actually responded.

These findings suggest that for small changes in our visual world, the way we perceive a shift and the way our body adapts to it are handled by different processes. The brain can register a visual change and tell us we are aware of it, while the motor system quietly makes the necessary adjustments without our conscious knowledge of the specific correction. The study indicates that perceptual awareness of a visuomotor rotation does not always translate into motor awareness during reaching tasks, particularly when the rotation is small. This implies that our conscious experience of an event and the automatic adjustments our body makes to navigate that event can operate on separate tracks, with one knowing more than the other.