Limits...
Movement speed is biased by prior experience.

Hammerbeck U, Yousif N, Greenwood R, Rothwell JC, Diedrichsen J - J. Neurophysiol. (2013)

Bottom Line: Reduced speed variability was also associated with reduced errors in movement amplitude for the fast training group, which generalized nearly fully to a new movement direction.In contrast, changes in perpendicular error were specific to the trained direction.In sum, our results suggest the existence of a relatively stable but modifiable prior of preferred movement speed that influences the choice of movement speed under a range of task constraints.

View Article: PubMed Central - PubMed

Affiliation: Institute of Neurology, University College London, London, United Kingdom;

ABSTRACT
How does the motor system choose the speed for any given movement? Many current models assume a process that finds the optimal balance between the costs of moving fast and the rewards of achieving the goal. Here, we show that such models also need to take into account a prior representation of preferred movement speed, which can be changed by prolonged practice. In a time-constrained reaching task, human participants made 25-cm reaching movements within 300, 500, 700, or 900 ms. They were then trained for 3 days to execute the movement at either the slowest (900-ms) or fastest (300-ms) speed. When retested on the 4th day, movements executed under all four time constraints were biased toward the speed of the trained movement. In addition, trial-to-trial variation in speed of the trained movement was significantly reduced. These findings are indicative of a use-dependent mechanism that biases the selection of speed. Reduced speed variability was also associated with reduced errors in movement amplitude for the fast training group, which generalized nearly fully to a new movement direction. In contrast, changes in perpendicular error were specific to the trained direction. In sum, our results suggest the existence of a relatively stable but modifiable prior of preferred movement speed that influences the choice of movement speed under a range of task constraints.

Show MeSH
Comparison of changes in maximum speed variability (A–C) due to training. A: data from the fast training group before (open) and after (closed) training for movement times of 900, 700, 500, and 300 ms. B: slow training group measures. C plots prepost change scores of maximum speed variability.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4527989&req=5

Figure 6: Comparison of changes in maximum speed variability (A–C) due to training. A: data from the fast training group before (open) and after (closed) training for movement times of 900, 700, 500, and 300 ms. B: slow training group measures. C plots prepost change scores of maximum speed variability.

Mentions: Reduced variability of peak speed observed during training (Fig. 3B) was also evident when inspecting the pre- and posttraining performance. Interestingly, the reduction was specific to the trained speed. The fast training group reduced the variability of movement speed mostly for the higher speeds (Fig. 6A), whereas the slow group decreased it mostly for the lower speeds (Fig. 6B). This training-specific effect can be seen most clearly in the pre- to posttest difference plots (Fig. 6C). A two-factor rmANOVA confirmed that there was a highly significant GROUP × TARGET SPEED interaction [F(3,48) = 5.047, P = 0.004]. Between-group, post hoc t-tests on the reduction of movement-speed variability was significantly changed for the fast training group [t(16) = −2.570, P = 0.021] and showed a trend for the slow group [t(16) = −2.037, P = 0.059]. The combination of a training-dependent movement-speed bias and a specific reduction in speed variability suggests similar mechanisms as has been observed for training-induced changes in movement direction (Verstynen and Sabes 2011).


Movement speed is biased by prior experience.

Hammerbeck U, Yousif N, Greenwood R, Rothwell JC, Diedrichsen J - J. Neurophysiol. (2013)

Comparison of changes in maximum speed variability (A–C) due to training. A: data from the fast training group before (open) and after (closed) training for movement times of 900, 700, 500, and 300 ms. B: slow training group measures. C plots prepost change scores of maximum speed variability.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4527989&req=5

Figure 6: Comparison of changes in maximum speed variability (A–C) due to training. A: data from the fast training group before (open) and after (closed) training for movement times of 900, 700, 500, and 300 ms. B: slow training group measures. C plots prepost change scores of maximum speed variability.
Mentions: Reduced variability of peak speed observed during training (Fig. 3B) was also evident when inspecting the pre- and posttraining performance. Interestingly, the reduction was specific to the trained speed. The fast training group reduced the variability of movement speed mostly for the higher speeds (Fig. 6A), whereas the slow group decreased it mostly for the lower speeds (Fig. 6B). This training-specific effect can be seen most clearly in the pre- to posttest difference plots (Fig. 6C). A two-factor rmANOVA confirmed that there was a highly significant GROUP × TARGET SPEED interaction [F(3,48) = 5.047, P = 0.004]. Between-group, post hoc t-tests on the reduction of movement-speed variability was significantly changed for the fast training group [t(16) = −2.570, P = 0.021] and showed a trend for the slow group [t(16) = −2.037, P = 0.059]. The combination of a training-dependent movement-speed bias and a specific reduction in speed variability suggests similar mechanisms as has been observed for training-induced changes in movement direction (Verstynen and Sabes 2011).

Bottom Line: Reduced speed variability was also associated with reduced errors in movement amplitude for the fast training group, which generalized nearly fully to a new movement direction.In contrast, changes in perpendicular error were specific to the trained direction.In sum, our results suggest the existence of a relatively stable but modifiable prior of preferred movement speed that influences the choice of movement speed under a range of task constraints.

View Article: PubMed Central - PubMed

Affiliation: Institute of Neurology, University College London, London, United Kingdom;

ABSTRACT
How does the motor system choose the speed for any given movement? Many current models assume a process that finds the optimal balance between the costs of moving fast and the rewards of achieving the goal. Here, we show that such models also need to take into account a prior representation of preferred movement speed, which can be changed by prolonged practice. In a time-constrained reaching task, human participants made 25-cm reaching movements within 300, 500, 700, or 900 ms. They were then trained for 3 days to execute the movement at either the slowest (900-ms) or fastest (300-ms) speed. When retested on the 4th day, movements executed under all four time constraints were biased toward the speed of the trained movement. In addition, trial-to-trial variation in speed of the trained movement was significantly reduced. These findings are indicative of a use-dependent mechanism that biases the selection of speed. Reduced speed variability was also associated with reduced errors in movement amplitude for the fast training group, which generalized nearly fully to a new movement direction. In contrast, changes in perpendicular error were specific to the trained direction. In sum, our results suggest the existence of a relatively stable but modifiable prior of preferred movement speed that influences the choice of movement speed under a range of task constraints.

Show MeSH