Error processing in implicit correction during visually and memory-guided reaching movements.

Motor adaptation allows us to adjust our precise movements to maintain accuracy. The implicit motor correction is one of the main processes in adaptation, yet its underlying mechanisms are not fully understood. To elicit the implicit adaptation, the nervous system must properly estimate the cause of the errors. Recent studies have reported that there is a difference in the adaptation between the visually guided and memory-guided tasks. However, it remains unclear which aspects of the task conditions influence this difference. We hypothesized that the task conditions modulate the error processing. Therefore, this study attempted to test this hypothesis, examining the responses to various error sizes in the visually guided and memory-guided tasks. We observed the implicit single-trial motor correction to the clamped feedback, which was presented at a fixed location relative to a target, not the actual hand location. Our results showed a significant interaction between the error size and the task conditions. The applied relevance estimation model and the perceptual error adaptation model revealed differences in the uncertainty of sensorimotor integration across task conditions. This difference is likely to be caused by the higher cognitive demands of the memory-guided task. Therefore, our findings suggest that the error processing could be dissociated by the task conditions, which influence motor adaptation.NEW & NOTEWORTHY Implicit adaptation, which is an unconscious process in motor adaptation, has typically been investigated using the visually guided reaching task. To clarify this, we examined the relevance of error in the memory-guided reaching task, driven by internal representation, compared with the visually guided task. Our results revealed that the error processing could be dissociated by the task conditions, suggesting that the task context changes how the brain treats errors.