my subject today is learning. and in that spirit, i want to spring on you all a pop quiz. ready? when does learning begin? now as you ponder that question, maybe you're thinking about the first day of preschool or kindergarten, the first time that kids are in a classroom with a teacher. or maybe you've called to mind the toddler phase when children are learning how to walk and talk and use a fork. maybe you've encountered the zero-to-three movement, which asserts that the most important years for learning are the earliest ones. and so your answer to my question would be: learning begins at birth.
well today i want to present to you an idea that may be surprising and may even seem implausible, but which is supported by the latest evidence from psychology and biology. and that is that some of the most important learning we ever do happens before we're born, while we're still in the womb. now i'm a science reporter. i write books and magazine articles. and i'm also a mother. and those two roles came together for me in a book that i wrote called "origins." "origins" is a report from the front lines of an exciting new field called fetal origins. fetal origins is a scientific discipline that emerged just about two decades ago, and it's based on the theory that our health and well-being throughout our lives is crucially affected by the nine months we spend in the womb. now this theory was of more than just intellectual interest to me. i was myself pregnant while i was doing the research for the book. and one of the most fascinating insights i took from this work is that we're all learning about the world even before we enter it.
when we hold our babies for the first time, we might imagine that they're clean slates, unmarked by life, when in fact, they've already been shaped by us and by the particular world we live in. today i want to share with you some of the amazing things that scientists are discovering about what fetuses learn while they're still in their mothers' bellies.
first of all, they learn the sound of their mothers' voices. because sounds from the outside world have to travel through the mother's abdominal tissue and through the amniotic fluid that surrounds the fetus, the voices fetuses hear, starting around the fourth month of gestation, are muted and muffled. one researcher says that they probably sound a lot like the the voice of charlie brown's teacher in the old "peanuts" cartoon. but the pregnant woman's own voice reverberates through her body, reaching the fetus much more readily. and because the fetus is with her all the time, it hears her voice a lot. once the baby's born, it recognizes her voice and it prefers listening to her voice over anyone else's.
how can we know this? newborn babies can't do much, but one thing they're really good at is sucking. researchers take advantage of this fact by rigging up two rubber nipples, so that if a baby sucks on one, it hears a recording of its mother's voice on a pair of headphones, and if it sucks on the other nipple, it hears a recording of a female stranger's voice. babies quickly show their preference by choosing the first one. scientists also take advantage of the fact that babies will slow down their sucking when something interests them and resume their fast sucking when they get bored. this is how researchers discovered that, after women repeatedly read aloud a section of dr. seuss' "the cat in the hat" while they were pregnant, their newborn babies recognized that passage when they hear it outside the womb. my favorite experiment of this kind is the one that showed that the babies of women who watched a certain soap opera every day during pregnancy recognized the theme song of that show once they were born. so fetuses are even learning about the particular language that's spoken in the world that they'll be born into.