title: Estimating the implicit component of visuomotor rotation learning by constraining movement preparation time.
abstract: When sensory feedback is perturbed, accurate movement is restored by a combination of implicit processes and deliberate reaiming to strategically compensate for errors. Here, we directly compare two methods used previously to dissociate implicit from explicit learning on a trial-by-trial basis:1) asking participants to report the direction that they aim their movements, and contrasting this with the directions of the target and the movement that they actually produce, and2) manipulating movement preparation time. By instructing participants to reaim without a sensory perturbation, we show that reaiming is possible even with the shortest possible preparation times, particularly when targets are narrowly distributed. Nonetheless, reaiming is effortful and comes at the cost of increased variability, so we tested whether constraining preparation time is sufficient to suppress strategic reaiming during adaptation to visuomotor rotation with a broad target distribution. The rate and extent of error reduction under preparation time constraints were similar to estimates of implicit learning obtained from self-report without time pressure, suggesting that participants chose not to apply a reaiming strategy to correct visual errors under time pressure. Surprisingly, participants who reported aiming directions showed less implicit learning according to an alternative measure, obtained during trials performed without visual feedback. This suggests that the process of reporting can affect the extent or persistence of implicit learning. The data extend existing evidence that restricting preparation time can suppress explicit reaiming and provide an estimate of implicit visuomotor rotation learning that does not require participants to report their aiming directions.NEW & NOTEWORTHYDuring sensorimotor adaptation, implicit error-driven learning can be isolated from explicit strategy-driven reaiming by subtracting self-reported aiming directions from movement directions, or by restricting movement preparation time. Here, we compared the two methods. Restricting preparation times did not eliminate reaiming but was sufficient to suppress reaiming during adaptation with widely distributed targets. The self-report method produced a discrepancy in implicit learning estimated by subtracting aiming directions and implicit learning measured in no-feedback trials.
authors.affiliation: Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, Building 26B, The University of Queensland, Brisbane, Queensland, Australia; and l.leow@uq.edu.au.
authors.forename: Li-Ann
authors.identifier: 0000-0002-9655-3181
authors.initials: LA
authors.lastname: Leow
authors.affiliation: Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, Building 26B, The University of Queensland, Brisbane, Queensland, Australia; and.
authors.forename: Reece
authors.initials: R
authors.lastname: Gunn
authors.affiliation: Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, Building 26B, The University of Queensland, Brisbane, Queensland, Australia; and.|School of Psychology and Speech Pathology, Curtin University, Bentley, Western Australia, Australia.
authors.forename: Welber
authors.identifier: 0000-0002-2472-7955
authors.initials: W
authors.lastname: Marinovic
authors.affiliation: Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, Building 26B, The University of Queensland, Brisbane, Queensland, Australia; and.
authors.forename: Timothy J
authors.identifier: 0000-0003-0761-1819
authors.initials: TJ
authors.lastname: Carroll
mesh_terms: D000223:Adaptation, Psychological / Q000502:physiology; D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D056228:Feedback, Sensory; D005260:Female; D006225:Hand / Q000502:physiology; D006801:Humans; D007858:Learning / Q000502:physiology; D008297:Male; D009043:Motor Activity / Q000502:physiology; D012399:Rotation; D013997:Time Factors; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult
keywords: compensatory strategies; explicit learning; implicit learning; motor learning; visuomotor rotation