The documentation of learning and memory months before birth is surprising. Some of this has been made possible by direct ultrasound observations of fetal behavior. Twins can be seen developing certain gestures and habits at twenty weeks gestational age which persist into their postnatal years. At one year of age, their favorite game was to take positions on opposite sides of a curtain, and begin to laugh and giggle as they touched each other and played through the curtain. When the baby kicks, they move to a different location and repeat the invitation.
Babies soon oblige by kicking anywhere on cue.
In a famous experiment by Anthony DeCasper and colleagues at the University of North Carolina, Greensboro, mothers read the Dr. Seuss story, The Cat In the Hat, at regular intervals before birth. At birth, babies were hooked up to recordings which they could select by sucking on a non-nutritive nipple. In a recent experiment, French mothers repeated a children's rhyme each day from week 33 to week 37 of gestation. Babies are leaning their native language before birth. This is made possible by the development of hearing as early as 16 weeks gestational age.