A fetus’s heart leaps up not because he hears Wordsworth’s immortal verse but because he recognizes his mother’s voice. While research has shown newborns prefer their mother’s voice to that of a woman unknown to them, a Canadian study is the first to confirm this preference in unborn children. Led by Dr. Barbara Kisilevsky, a Queen’s University professor of nursing in Kingston, Ont., a team of psychologists at Queen’s and obstetricians at Zhejiang University in China monitored 60 at-term fetuses. They observed a marked acceleration in fetal heart rates in response to two-minute audiotapes in which the pregnant moms read out a poem. Their heart rates slowed down at the sound of a female stranger reading the same poem. In Kisilevsky’s view, these findings show that fetuses are capable of sustained attention and memory formation. She also believes that their experiences in the womb help forge the mother-newborn attachment and lay the ground for a child’s speech perception and language skills.