LEARNING TO REACH - A MATHEMATICAL-MODEL

This article presents a mathematical model of the development of reach ing that assumes that the major problem facing infants is their lack o f lower level motor control and that infants learn to adjust their rea ching strategies as a consequence of their previous experience and to match their current level of control. The model hypothesizes that infa nt reaches are a series of submovements, with the goal being to get th e hand to tile target in the face of errors in executed submovements. To relate actual infant reaches to this model, reaching data were deco mposed into submovements, using a polynomial fitting algorithm that as sumed minimum-jerk submovements. The model makes quantitative predicti ons about the course of development that are supported by existing res ults. The validity of the model's underlying assumptions was assessed by comparing the directional variability of the submovements with the variability assumed in the model.