Motor learning occurs over long periods of practice during which motor acuity, the ability to execute actions more accurately, precisely, and in less time, improves. Laboratory-based studies of motor learning are typically limited to a small number of participants and a time frame of minutes to several hours per participant. There is a need to assess the generalizability of theories and findings from lab-based motor learning studies on larger samples and time scales. In addition, laboratory-based studies of motor learning use relatively simple motor tasks which participants are unlikely to be intrinsically motivated to learn, limiting the interpretation of their findings in more ecologically valid settings (“in the wild”). We studied the acquisition and longitudinal refinement of a complex sensorimotor skill embodied in a first-person shooter video game scenario, with a large sample size (N = 7174, 682,564 repeats of the 60 s game) over a period of months. Participants voluntarily practiced the gaming scenario for up to several hours per day up to 100 days. We found improvement in performance accuracy (quantified as hit rate) was modest over time but motor acuity (quantified as hits per second) improved considerably, with 40–60% retention from 1 day to the next. We observed steady improvements in motor acuity across multiple days of video game practice, unlike most motor learning tasks studied in the lab that hit a performance ceiling rather quickly. Learning rate was a non-linear function of baseline performance level, amount of daily practice, and to a lesser extent, number of days between practice sessions. In addition, we found that the benefit of additional practice on any given day was non-monotonic; the greatest improvements in motor acuity were evident with about an hour of practice and 90% of the learning benefit was achieved by practicing 30 min per day. Taken together, these results provide a proof-of-concept in studying motor skill acquisition outside the confines of the traditional laboratory, in the presence of unmeasured confounds, and provide new insights into how a complex motor skill is acquired in an ecologically valid setting and refined across much longer time scales than typically explored.

We introduce a novel perspective on how the cerebellum might contribute to cognition, hypothesizing that this structure supports dynamic transformations of mental representations. In support of this hypothesis, we report a series of neuropsychological experiments comparing the performance of individuals with degenerative cerebellar disorders (CD) on tasks that either entail continuous, movement-like mental operations or more discrete mental operations. In the domain of visual cognition, the CD group exhibited an impaired rate of mental rotation, an operation hypothesized to require the continuous manipulation of a visual representation. In contrast, the CD group showed a normal processing rate when scanning items in visual working memory, an operation hypothesized to require the maintenance and retrieval of remembered items. In the domain of mathematical cognition, the CD group was impaired at single-digit addition, an operation hypothesized to primarily require iterative manipulations along a mental number-line; this group was not impaired on arithmetic tasks linked to memory retrieval (e.g., single-digit multiplication). These results, obtained in tasks from two disparate domains, point to a potential constraint on the contribution of the cerebellum to cognitive tasks. Paralleling its role in motor control, the cerebellum may be essential for coordinating dynamic, movement-like transformations in a mental workspace.

Our duration estimation flexibly adapts to the statistical properties of the temporal context. Humans and non-human species exhibit a perceptual bias towards the mean of durations previously observed as well as serial dependence, a perceptual bias towards the duration of recently processed events. Here we asked whether those two phenomena arise from a unitary mechanism or reflect the operation of two distinct systems that adapt separately to the global and local statistics of the environment. We employed a set of duration reproduction tasks in which the target duration was sampled from distributions with different variances and means. The central tendency and serial dependence biases were jointly modulated by the range and the variance of the prior, and these effects were well-captured by a unitary mechanism model in which temporal expectancies are updated after each trial based on perceptual observations. Alternative models that assume separate mechanisms for global and local contextual effects failed to capture the empirical results.

The cerebellum is recognized to play a critical role in the automatic and implicit process by which movement errors are used to keep the sensorimotor system precisely calibrated. However, its role in other learning processes frequently engaged during sensorimotor adaptation tasks remains unclear. In the present study, we tested the performance of individuals with cerebellar degeneration on a variant of a visuomotor adaptation task in which learning requires the use of strategic re-aiming, a process that can nullify movement errors in a rapid and volitional manner. Our design allowed us to assess two components of this learning process, the discovery of an appropriate strategy and the recall of a learned strategy. Participants were exposed to a 60° visuomotor rotation twice, with the initial exposure block assessing strategy discovery and the re-exposure block assessing strategy recall. Compared to age-matched controls, individuals with cerebellar degeneration were slower to derive an appropriate aiming strategy in the initial Discovery block but exhibited similar recall of the aiming strategy during the Recall block. This dissociation underscores the multi-faceted contributions of the cerebellum to sensorimotor learning, highlighting one way in which this subcortical structure facilitates volitional action selection.

13Various lines of evidence implicate the cerebellum as one node in a network of neural regions engaged in 14 controlled cognitive processes. Characterizing the functional role of the cerebellum within this network, 15 and in cognition more broadly, has proven elusive. Motivated by models of how the cerebellum helps 16 coordinate movement, we propose that the cerebellum contributes to cognitive tasks that involve the 17 transformation of mental representations along a continuous dimension. To test this hypothesis, we 18 compared tasks that entail the continuous transformation of a single visual representation or discrete 19 computations over a set of visual representations. We predicted that individuals with cerebellar 20 degeneration (CD) would be selectively impaired on the former. Consistent with this prediction, two 21 independent CD groups were impaired on a mental rotation task, with the estimated rate of rotation slower 22 105˚, 135˚]. In the second task of Experiment 1 (Figure 1), participants were tested on a memory scanning 105 task. On each trial, the participant viewed either a single, or a sequence of abstract, visual fractal stimuli 106 (sequence length/load = 2-5 stimuli), and, after a brief maintenance period, were asked to judge whether a 107 probe stimulus was a member of the previous sequence (match) or not (non-match). This task is thought to 108 require participants to scan through (serially or in parallel) a set of distinct representations held in working 109 memory. 110 111 5 112 Figure 1: Design. In the mental rotation experiment, participants judged if a letter stimulus was normal (e.g., "R", 113right key press) or mirror-reflected (e.g., "Я", left key press). On most trials, the stimulus was rotated relative to the 114 upright orientation (an example 135˚ trial is shown). The same mental rotation task was used in both Experiments 1 115 and 2. In the first working memory search task (Experiment 1), a sequence of stimuli (2-5 images) was initially 116 presented (1 s per image). After a maintenance period (3 s), a probe stimulus was presented, and the participant judged 117 whether it was a member of the sequence (right key) or not (left key). Sequences varied in length from one to four 118 items. In the second working memory search task (Experiment 2), a sequence of targets (2-5 items) was presented at 119 random locations on a ring (1 s per target). After a maintenance period (2 s), a probe target was presented, and the 120 participant indicated the ordinal position of the target within the sequence (1-5 on the keyboard). Responses in all 121 tasks were followed by feedback (1 s), and a 1 s inter-trial-interval (ITI). 123 124 125 RT effects 126Both mental rotation and working memory search are known to produce a near-linear relationship 127 between RT and the experimentally titrated independent variable, rotation magnitude or set size (i.e., load). 128Replicating these classic results, regression slopes on the RT data (correct trials only) for both the mental 129 rotation and search condi...