What autocorrelation tells us about motor variability: insights from dart throwing

PLoS One. 2013 May 17;8(5):e64332. doi: 10.1371/journal.pone.0064332. Print 2013.

Abstract

In sports such as golf and darts it is important that one can produce ballistic movements of an object towards a goal location with as little variability as possible. A factor that influences this variability is the extent to which motor planning is updated from movement to movement based on observed errors. Previous work has shown that for reaching movements, our motor system uses the learning rate (the proportion of an error that is corrected for in the planning of the next movement) that is optimal for minimizing the endpoint variability. Here we examined whether the learning rate is hard-wired and therefore automatically optimal, or whether it is optimized through experience. We compared the performance of experienced dart players and beginners in a dart task. A hallmark of the optimal learning rate is that the lag-1 autocorrelation of movement endpoints is zero. We found that the lag-1 autocorrelation of experienced dart players was near zero, implying a near-optimal learning rate, whereas it was negative for beginners, suggesting a larger than optimal learning rate. We conclude that learning rates for trial-by-trial motor learning are optimized through experience. This study also highlights the usefulness of the lag-1 autocorrelation as an index of performance in studying motor-skill learning.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Analysis of Variance
  • Biomechanical Phenomena
  • Humans
  • Learning / physiology*
  • Male
  • Middle Aged
  • Models, Theoretical*
  • Motor Skills / physiology*
  • Psychomotor Performance*
  • Sports / physiology*

Grant support

This research was supported by the Netherlands Organisation for Scientific Research (http://www.nwo.nl/, NWO Grant 453-08-004). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.