i.kurtzer (2000.09.12.1430)
I just read a wonderful journal article "The functional significance of arm
movements in neonates" van der Meer et al (1995) Science, vol 267, pp
693-695. They show that the seemingly undirected armwaving of newborns is
controlled to keep the hand within the visual field. The child laid supine
and wore cuffs to the wrist. The cuff connnected to a pulley that applied a
force directed towards the toes. The infant could either see its arm by
orienting its head, thereby not seeing the contralateral arm, or see its
contralateral arm by a video monitor on the side it faced, or see neither
arm by having occluders on the side of the head. When the arm was in view,
either directly or by video monitor, the mean position was independent of
the applied forces, up to 25% of the weight of the arm. That is, the
infants kept their hand within their visual field. Further, the arm was
moved back in forth in large amplitudes. Instead, when the arm was out of
view it was no longer waved and its mean position was increasingly towards
the toes as more weights were added.
enjoy
i.