Visuomotor rotations are frequently used to study the different processes underlying motor adaptation. Explicit aiming strategies and implicit recalibration are two of these processes. Various methods, which differ in their underlying assumptions, have been used to dissociate the two processes. Direct methods, such as verbal reports, assume explicit knowledge to be verbalizable, where indirect methods, such as the exclusion, assume that explicit knowledge is controllable. The goal of this study was thus to directly compare verbal reporting with exclusion in two different conditions: during consistent reporting and during intermittent reporting. Our results show that our two conditions lead to a dissociation between the measures. In the consistent reporting group, all measures showed similar results. However, in the intermittent reporting group, verbal reporting showed more explicit re‐aiming and less implicit adaptation than exclusion. Curiously, when exclusion was measured again, after the end of learning, the differences were no longer apparent. We suspect this may reflect selective decay in implicit adaptation, as has been reported previously. All told, our results clearly indicate that methods of measurement can affect the amount of explicit re‐aiming and implicit adaptation that is measured. Since it has been previously shown that both explicit re‐aiming and implicit adaptation have multiple components, discrepancies between these different methods may arise because different measures reflect different components.

One persistent curiosity in visuomotor adaptation tasks is that participants often do not reach maximal performance. This incomplete asymptote has been explained as a consequence of obligatory computations within the implicit adaptation system, such as an equilibrium between learning and forgetting. A body of recent work has shown that in standard adaptation tasks, cognitive strategies operate alongside implicit learning. We reasoned that incomplete learning in adaptation tasks may primarily reflect a speed-accuracy tradeoff on time-consuming motor planning. Across three experiments, we find evidence supporting this hypothesis, showing that hastened motor planning may primarily lead to under-compensation. When an obligatory waiting period was administered before movement start, participants were able to fully counteract imposed perturbations (Experiment 1). Inserting the same delay between trials – rather than during movement planning – did not induce full compensation, suggesting that the motor planning interval influences the learning asymptote (Experiment 2). In the last experiment (Experiment 3), we asked participants to continuously report their movement intent. We show that emphasizing explicit re-aiming strategies (and concomitantly increasing planning time) also lead to complete asymptotic learning. Findings from all experiments support the hypothesis that incomplete adaptation is, in part, the result of an intrinsic speed-accuracy tradeoff, perhaps related to cognitive strategies that require parametric attentional reorienting from the visual target to the goal.

Visuomotor rotations are frequently used to study cognitive processes underlying motor adaptation.Explicit aiming strategies and implicit recalibration are two of these processes. A large body of literature indicates that these two processes are dissociable and perhaps even independent components. Various direct and indirect methods have been used to dissociate the two processes.Discrepancies have been found between these different methods. They may arise for different reasons, but one reason may be that the different measures reflect different components of explicit and implicit knowledge. They may also be because of effects of the measurements themselves on the amount of explicit and implicit learning. The goal of this study was to directly compare verbal reporting, a direct measure of explicit knowledge, with indirect measures. We thus compared three different measures in two different conditions: during consistent reporting and during intermittent reporting. Our results show that our two conditions lead to a dissociation between the measures. In the consistent reporting group, all measures showed similar results. However, in the intermittent reporting condition, verbal reporting showed less explicit and more implicit knowledge than our two indirect methods. Verbal reporting seems to be insensitive to the changes in explicit knowledge caused by reporting. These findings suggest that verbal reporting reflects different components of explicit knowledge than those reflected in our indirect measures. A more sophisticated approach, including multiple components of explicit knowledge, may be necessary in order to fully understand motor adaptation. New and noteworthyExplicit and implicit processes during adaptation to visuomotor rotations can be captured using different types of measures. Here, we show that different methods may capture different processes and moreover, measurement may confound estimates of explicit and implicit knowledge. We suggest that at least two explicit components -one that is verbalizable and the other controllable -exist which can be captured by using the report and the AI, respectively.Reporting affects explicit knowledge in visuomotor rotations

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20One persistent curiosity in visuomotor adaptation tasks is the fact that participants often 21 reach a learning asymptote well below full compensation. This incomplete asymptote has been 22 manipulating the planning time, we asked participants to continuously report their movement 34 aim. We show that emphasizing explicit re-aiming strategies also leads to full asymptotic 35 learning, supporting the idea that prolonged motor planning may involve a parametric rotation 36 of aiming direction whose premature termination yields incomplete asymptotic learning 37 (experiment 3). Findings from all experiments support the hypothesis that incomplete 38 adaptation is, in part, the result of an intrinsic speed-accuracy tradeoff, perhaps related to 39 cognitive strategies that require parametric attentional reorienting from the visual target to the 40 goal. 41 42