Measuring motor awareness and metacognition at the start, middle, and end of a reaching movement

The ability to monitor our arm position during goal-directed behaviour allows us to bring our limb to a target as accurately as possible. Despite our success in executing accurate movements, some work suggests that individuals have limited access to information about their limb position. However, other evidence from metacognition research indicates that people have some access to details about their movements. In these studies, individuals are asked to rate their confidence after making judgements about their movements and tend to give higher confidence ratings when they are correct, showing some capacity for self-monitoring. These conflicting results suggest that we may not be able to monitor an entire movement from start to end. In the current study, participants (n = 50) made reaching movements toward targets on a screen. They were then visually presented with two movement paths: one being their actual trajectory and the other being a visually deviated version. Here, we manipulated the location that the deviation was implemented (i.e., start, middle, or end of the path). Participants were then asked to determine which trajectory was their own, while also rating their confidence in their response. Overall, accuracy was lower than expected. Nevertheless, accuracy was significantly lower when deviations occurred at the start of the reach, indicating that awareness of limb position is further reduced at the start of a movement. Additionally, participants were able to metacognitively monitor their movements because their confidence scaled with their accuracy in the task. Finally, differences in metacognitive processes between locations were found, with higher average confidence in the middle of a movement when accuracy was held constant. We conclude that people have a remarkable blindness to the properties of their own movements. As well, monitoring of a limb is significantly reduced at the start of a movement suggesting reduced attention to limb position at this time, possibly due to movement programming demands.