“Leap before you look”: Conditions that suppress explicit, knowledge-based learning during visuomotor adaptation.

Abstract

When learning a novel visuomotor mapping (e.g., mirror writing), accuracy can improve quickly through explicit, knowledge-based learning (e.g., aim left to go right), but after practice, implicit or procedural learning takes over, producing fast, natural movements. This procedural learning occurs automatically, whereas it has recently been found that knowledge-based learning can be suppressed by the gradual introduction of the novel mapping when participants must make fast movements and visuomotor perturbations are small (e.g., 30°rotations). We explored the range of task instructions, perturbation parameters, and feedback that preclude or encourage this suppression. Using a reaching task with a rotation between screen position and movement direction, we found that knowledge-based learning could be suppressed even for an extreme 90°rotation, but only if it was introduced gradually and only under instructions to move quickly. If the rotation was introduced abruptly or if instructions emphasized accuracy over speed, knowledge-based learning occurred. A second experiment indicated that knowledge-based learning always occurred in the absence of continuous motion feedback, evidenced by the time course of learning, the aftereffects of learning when the rotation was abruptly removed, and the outcome of formal model comparison between a dual-state (procedural and knowledge-based) versus a single-state (procedural only) learning model of the data. A third experiment replicated the findings and verified that the knowledge-based component of the dual-state model corresponded to explicit aiming, whereas the procedural component was slow to unlearn. Public Significance StatementSome situations require adaptation to a novel mapping between visual directions and motor directions, such as when attempting to cut one's own hair in the mirror. Prior results established that slowly learned procedural adaptation to a novel visuomotor mapping is automatic and always occurs. More recent results established that explicit, knowledge-based learning (e.g., a learned strategy to move left for a rightward target or to move south for a target located due east) can be suppressed by introducing the novel mapping gradually. The current study replicates this finding and demonstrates that this suppression can occur even for visuomotor remappings of large magnitude (a rotation of 90°). Importantly, it also establishes that this suppression does not occur when task instructions emphasize accuracy nor in the absence of continuous online visual feedback during motor actions.