Adaptation to Separate Kinematic and Dynamic Transformations in Children and Adults

Abstract

The question addressed in the present study is whether children and adults are able to combine and decompose separate kinematic (visual-feedback-shift) and dynamic (velocity-dependent force) transformations in goal-directed arm movements. A total of 64 participants (32 adults and 32 children) performed horizontal forearm movements using a single-joint arm manipulandum. When participants first learned kinematic and dynamic transformations separately, target error decreased in a subsequent combined transformation task. This effect was based on previous learning of the kinematic transformation. When they first learned the combined transformation, target error was smaller in the following kinematic-but not in the dynamic-transformation. No difference was found in adaptation performance between children and adults. The results suggest that there are two separate models for the kinematic and dynamic transformation and that a possible differentiation of kinematic and dynamic features of the motor task might already be present at age 11.

An overview of adaptive model theory: solving the problems of redundancy, resources, and nonlinear interactions in human movement control

“…In AMT the TDSG and the forward and inverse input/output relationships of the MCS, BM and E systems are modeled independently and in parallel. This has been shown experimentally for dynamic and kinematic systems (Krakauer et al 1999, Jansen-Osmann et al 2005. It cannot happen with feedback error learning (Kawato and Gomi 1992) where the learned model corresponds to the inverse of the entire plant.…”

“…As indicated earlier, reach and grasp behavior is well established experimentally as having at least two underlying control DFs. Also, subjects can perform a two DF visual pursuit tracking task with no greater a central time delay than required to perform a one DF task (Navon et al 1984, Oytam et al 1998, 2005. This is an important finding.…”