A baby still in the womb can tell the difference between its mother's voice and that of a stranger, writes Philip Fine.
A Canadian-Chinese study may help confirm the theory that the foundation for language acquisition is laid before birth.
Sixty near-term foetuses were played two different recordings and then monitored for their reactions. Expectant mothers had been asked to read the Mandarin equivalent of a Mother Goose tale for two minutes, which was later played near their bellies and at the same decibel level of a phone conversation, in between two two-minute silences. A stranger's voice reading the same poem was also played.
The researchers found that when exposed to its mother's voice, the average heart rate of the babies sped up by a sustained five beats a minute, and slowed by a sustained four beats a minute when the voice was unfamiliar.
Researchers from Queen's University in Kingston, Ontario, and the Zhejiang University School of Medicine in Hangzhou province said the results suggested that foetuses are not only capable of remembering and recognising characteristics of their mother's voice but that in utero speech processing may be using higher brain functioning than previously thought.
Earlier research has shown that foetuses are able to discriminate between sounds and a change in the gender of the speaker, but no research has recorded such a markedly different response to the novel and familiar, in this case, mother and stranger.
Lead author Barbara Kisilevsky said a foetus sets up a form of self-protection for its own pending vulnerabilities. "Here we have a human baby, born into the world completely helpless. Its heart rate changes when it hears its mother's voice before birth," she said, suggesting that "the organism is setting up an attachment for after birth". The study was published in the journal Psychological Science .