August 2014
Volume 14, Issue 10
Free
Vision Sciences Society Annual Meeting Abstract  |   August 2014
We know our own movement errors, but we hardly correct for then: An instance of optimal behavior
Author Affiliations
  • Marc Ernst
    Bielefeld University, Cognitive Neuroscience & CITEC
  • Loes van Dam
    Bielefeld University, Cognitive Neuroscience & CITEC
Journal of Vision August 2014, Vol.14, 837. doi:10.1167/14.10.837
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      Marc Ernst, Loes van Dam; We know our own movement errors, but we hardly correct for then: An instance of optimal behavior. Journal of Vision 2014;14(10):837. doi: 10.1167/14.10.837.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Random errors are omnipresent in sensorimotor tasks due to perceptual and motor noise. The question is, whether humans are aware of their random errors on a trial-by-trial basis? The appealing answer would be 'no' because it seems intuitive that humans would otherwise immediately correct for their movement errors online, thereby increasing sensorimotor precision. However, here we show the opposite (van Dam & Ernst, PLoS One, 2013). Participants pointed to visual targets with varying degree of feedback. After movement completion participants indicated whether they believed they landed left or right of target. Surprisingly, participants' left/right-discriminability was well above chance, even without visual feedback (Experiment 1). Only when forced to correct for the error after movement completion did participants loose knowledge about the remaining error, indicating that random errors can only be accessed offline (Experiment 2). When correcting, participants applied the optimal correction gain, a weighting factor between perceptual and motor noise, minimizing end-point variance. Together these results show that humans optimally combine direct information about sensorimotor noise in the system (the current random error), with indirect knowledge about the variance of the perceptual and motor noise distributions. Yet, they only appear to do so offline after movement completion, not while the movement is still in progress, suggesting that during movement proprioceptive information is less precise.

Meeting abstract presented at VSS 2014

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