Invariant errors reveal limitations in motor correction rather than constraints on error sensitivity

• Published in: Communications biology 2018-03, Vol.1 (1), p.19, Article 19
• Main Authors: Kim, Hyosub E., Morehead, J. Ryan, Parvin, Darius E., Moazzezi, Reza, Ivry, Richard B.
• Format: Article
• Language: English
• Subjects: 631/378/116/2396; 631/378/2632; 631/378/2632/1368; Adaptation; Biology; Biomedical and Life Sciences; Error correction & detection; Learning; Life Sciences; Sensorimotor system; Visual perception
• ISSN: 2399-3642; 2399-3642
• DOI: 10.1038/s42003-018-0021-y

Implicit sensorimotor adaptation is traditionally described as a process of error reduction, whereby a fraction of the error is corrected for with each movement. Here, in our study of healthy human participants, we characterize two constraints on this learning process: the size of adaptive corrections is only related to error size when errors are smaller than 6°, and learning functions converge to a similar level of asymptotic learning over a wide range of error sizes. These findings are problematic for current models of sensorimotor adaptation, and point to a new theoretical perspective in which learning is constrained by the size of the error correction, rather than sensitivity to error. Kim et al. report a study of implicit sensorimotor adaptation using task-irrelevant clamped visual feedback and find that learning is constrained primarily by the size of the error correction rather than sensitivity to error. The results present a challenge to current models of adaptation and suggest a new framework to guide new models of this process.