A Hessian-based decomposition characterizes how performance in complex motor skills depends on individual strategy and variability.

In complex real-life motor skills such as unconstrained throwing, performance depends on how accurate is on average the outcome of noisy, high-dimensional, and redundant actions. What characteristics of the action distribution relate to performance and how different individuals select specific actio...

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Autores principales: Paolo Tommasino, Antonella Maselli, Domenico Campolo, Francesco Lacquaniti, Andrea d'Avella
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Publicado: Public Library of Science (PLoS) 2021
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spelling oai:doaj.org-article:a295cb74a1cc471b9938ce760dc5f8da2021-12-02T20:15:44ZA Hessian-based decomposition characterizes how performance in complex motor skills depends on individual strategy and variability.1932-620310.1371/journal.pone.0253626https://doaj.org/article/a295cb74a1cc471b9938ce760dc5f8da2021-01-01T00:00:00Zhttps://doi.org/10.1371/journal.pone.0253626https://doaj.org/toc/1932-6203In complex real-life motor skills such as unconstrained throwing, performance depends on how accurate is on average the outcome of noisy, high-dimensional, and redundant actions. What characteristics of the action distribution relate to performance and how different individuals select specific action distributions are key questions in motor control. Previous computational approaches have highlighted that variability along the directions of first order derivatives of the action-to-outcome mapping affects performance the most, that different mean actions may be associated to regions of the actions space with different sensitivity to noise, and that action covariation in addition to noise magnitude matters. However, a method to relate individual high-dimensional action distribution and performance is still missing. Here we introduce a decomposition of performance into a small set of indicators that compactly and directly characterize the key performance-related features of the distribution of high-dimensional redundant actions. Central to the method is the observation that, if performance is quantified as a mean score, the Hessian (second order derivatives) of the action-to-score function determines how the noise of the action distribution affects performance. We can then approximate the mean score as the sum of the score of the mean action and a tolerance-variability index which depends on both Hessian and action covariance. Such index can be expressed as the product of three terms capturing noise magnitude, noise sensitivity, and alignment of the most variable and most noise sensitive directions. We apply this method to the analysis of unconstrained throwing actions by non-expert participants and show that, consistently across four different throwing targets, each participant shows a specific selection of mean action score and tolerance-variability index as well as specific selection of noise magnitude and alignment indicators. Thus, participants with different strategies may display the same performance because they can trade off suboptimal mean action for better tolerance-variability and higher action variability for better alignment with more tolerant directions in action space.Paolo TommasinoAntonella MaselliDomenico CampoloFrancesco LacquanitiAndrea d'AvellaPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 16, Iss 6, p e0253626 (2021)
institution DOAJ
collection DOAJ
language EN
topic Medicine
R
Science
Q
spellingShingle Medicine
R
Science
Q
Paolo Tommasino
Antonella Maselli
Domenico Campolo
Francesco Lacquaniti
Andrea d'Avella
A Hessian-based decomposition characterizes how performance in complex motor skills depends on individual strategy and variability.
description In complex real-life motor skills such as unconstrained throwing, performance depends on how accurate is on average the outcome of noisy, high-dimensional, and redundant actions. What characteristics of the action distribution relate to performance and how different individuals select specific action distributions are key questions in motor control. Previous computational approaches have highlighted that variability along the directions of first order derivatives of the action-to-outcome mapping affects performance the most, that different mean actions may be associated to regions of the actions space with different sensitivity to noise, and that action covariation in addition to noise magnitude matters. However, a method to relate individual high-dimensional action distribution and performance is still missing. Here we introduce a decomposition of performance into a small set of indicators that compactly and directly characterize the key performance-related features of the distribution of high-dimensional redundant actions. Central to the method is the observation that, if performance is quantified as a mean score, the Hessian (second order derivatives) of the action-to-score function determines how the noise of the action distribution affects performance. We can then approximate the mean score as the sum of the score of the mean action and a tolerance-variability index which depends on both Hessian and action covariance. Such index can be expressed as the product of three terms capturing noise magnitude, noise sensitivity, and alignment of the most variable and most noise sensitive directions. We apply this method to the analysis of unconstrained throwing actions by non-expert participants and show that, consistently across four different throwing targets, each participant shows a specific selection of mean action score and tolerance-variability index as well as specific selection of noise magnitude and alignment indicators. Thus, participants with different strategies may display the same performance because they can trade off suboptimal mean action for better tolerance-variability and higher action variability for better alignment with more tolerant directions in action space.
format article
author Paolo Tommasino
Antonella Maselli
Domenico Campolo
Francesco Lacquaniti
Andrea d'Avella
author_facet Paolo Tommasino
Antonella Maselli
Domenico Campolo
Francesco Lacquaniti
Andrea d'Avella
author_sort Paolo Tommasino
title A Hessian-based decomposition characterizes how performance in complex motor skills depends on individual strategy and variability.
title_short A Hessian-based decomposition characterizes how performance in complex motor skills depends on individual strategy and variability.
title_full A Hessian-based decomposition characterizes how performance in complex motor skills depends on individual strategy and variability.
title_fullStr A Hessian-based decomposition characterizes how performance in complex motor skills depends on individual strategy and variability.
title_full_unstemmed A Hessian-based decomposition characterizes how performance in complex motor skills depends on individual strategy and variability.
title_sort hessian-based decomposition characterizes how performance in complex motor skills depends on individual strategy and variability.
publisher Public Library of Science (PLoS)
publishDate 2021
url https://doaj.org/article/a295cb74a1cc471b9938ce760dc5f8da
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