Signatures of contextual interference in implicit sensorimotor adaptation

Abstract

Contextual interference refers to the phenomenon whereby a blocked practice schedule results in faster acquisition but poorer retention of new motor skills compared to a random practice schedule. While contextual interference has been observed under a broad range of tasks, it remains unclear if this effect generalizes to the implicit and automatic recalibration of an overlearned motor skill. To address this question, we compared blocked and random practice schedules in a visuomotor rotation task that isolates implicit adaptation. In experiment 1, we found robust signatures of contextual interference in implicit adaptation: compared to participants tested under a blocked training schedule, participants tested under a random training schedule exhibited a reduced rate of learning during the training phase but better retention during a subsequent no-feedback assessment phase. In experiment 2, we again observed an advantage in retention following random practice and showed that this result was not due to a change in context between the training and assessment phases (e.g. a blocked training schedule followed by a random assessment schedule). Taken together, these results indicate that contextual interference is not limited to the acquisition of new motor skills but also applies to the implicit adaptation of established motor skills.

Keywords: contextual interference; error-based learning; motor learning; visuomotor adaptation.

Figure 1.

Contextual interference is observed in implicit sensorimotor adaptation. (a) Schematic of the clamped feedback task. The cursor feedback (black circle) follows a constant trajectory rotated relative to the target (Exp 1: 30°, 45°, and 60°; Exp 2: 45°), independent of the position of the participant's hand. Participants were instructed to always move directly to the target (blue circle) and ignore the visual clamped feedback. Left, middle and right panels display hand and cursor positions during the early, late and aftereffect phases of adaptation, respectively. (b, e, h) Mean time courses of hand angle in each experiment. The blocked training group is shown in black, and the random training group is shown in orange. Shaded error bars denote SEM. (c, f, i) Retention as a function of training schedule. (d, g, j) Retention delineated by the order of targets during the training phase (d, g) or by the order of targets during the no-feedback assessment phase (j). Dashed orange line denotes the mean retention over all three targets for the random training group. These targets were interleaved, and therefore do not have a specific order. Box plots show minimum, median, maximum and 1st/3rd IQR. Dots denote individuals. *p < 0.05.

Figure 2.

Comparing random and blocked training across all experimental conditions: (a) early adaptation, (b) late adaptation and (c) retention. Box plots show min, median, max and 1st/3rd IQR. *p < 0.05. Dots denote individuals (n = 360). Outlier individuals greater than 1st/3rd IQR are not shown.