The development of hand preference in infant reaching is marked by several
lateral fluctuations. This study investigated whether similar lateral fluct
uations were present in infants' spontaneous, nonreaching, and freely perfo
rmed movements. We collected reaching and nonreaching movements kinematics
in 4 infants that we followed longitudinally during their 1st year. In thei
r 4th year we assessed the direction of their hand preference. We found tha
t lateral biases in spontaneous, nonreaching movements in the 1st year show
ed several shifts that were similar to those observed in reaching. Despite
these shifts, all 4 infants traversed a short period of right-handedness. T
his right-handedness matched the direction of their hand preference at 3 ye
ars of age. We propose that shifts in the development of hand preference in
the 1st year are linked to successive reorganizations of the motor system.
These reorganizations take place as infants learn to sit, crawl, and walk.
(C) 1999 John Wiley & Sons, Inc.