The effects of working memory resource depletion and training on sensorimotor adaptation

Abstract

We have recently demonstrated that visuospatial working memory performance predicts the rate of motor skill learning, particularly during the early phase of visuomotor adaptation. Here, we follow up these correlational findings with direct manipulations of working memory resources to determine the impact on visuomotor adaptation, a form of motor learning. We conducted two separate experiments. In the first one, we used a resource depletion strategy to investigate whether the rate of early visuomotor adaptation would be negatively affected by fatigue of spatial working memory resources. In the second study, we employed a dual n-back task training paradigm that has been shown to result in transfer effects [1] over five weeks to determine whether training-related improvements would boost the rate of early visuomotor adaptation. The depletion of spatial working memory resources negatively affected the rate of early visuomotor adaptation. However, enhancing working memory capacity via training did not lead to improved rates of visuomotor adaptation, suggesting that working memory capacity may not be the factor limiting maximal rate of visuomotor adaptation in young adults. These findings are discussed from a resource limitation/capacity framework with respect to current views of motor learning.

Figure 1

Schematic depiction of the basic design of Experiment 1.

Figure 2

Spatial working memory performance across each block (group mean ± SE). The spatial working memory fatigue index was calculated by subtracting mean performance across blocks 1–6 from mean performance across blocks 7–14.

Figure 3

Visuomotor adaptation task performance for participants who underwent spatial working memory resource depletion (group mean ± SD). Blocks 1 and 2 were performed under veridical visual feedback, whereas Blocks 3–7 were performed under 30° clockwise rotation of the display about the center of the screen.

Figure 4

Correlation between the rate of early adaptation and spatial working memory accuracy difference score assessing the fatiguing of spatial working memory resources (r= −.42, p= .023).

Figure 5

Figure 5A. Mean performance over the course of training for the NB group (average level of n reached during each session). 5B: Mean performance over the course of training for the KT group (average number of questions answered correctly in each training session).

Figure 6

Visuomotor adaptation task performance for training participants (group mean ± SD). Blocks 1 (baseline) and 12–13 (after-effects) were performed under veridical visual feedback, whereas Blocks 2–11 (adaptation) were performed under 30° clockwise rotation of the display about the center of the screen. Pre refers to performance prior to training, Post refers to performance afterwards. NB: n-back task training group, KT: knowledge training group.