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.