According to new research published in the journal NeuroReport, a month before they are born, fetuses can distinguish between someone speaking to them in English and Japanese.
Dr. Gustafson with a mother-to-be in the fetal biomagnetometer. Image credit: University of Kansas.
“Research suggests that human language development may start really early — a few days after birth,” said lead author Dr. Utako Minai, an associate professor at the University of Kansas.
“Babies a few days old have been shown to be sensitive to the rhythmic differences between languages.”
“Previous studies have demonstrated this by measuring changes in babies’ behavior; for example, by measuring whether babies change the rate of sucking on a pacifier when the speech changes from one language to a different language with different rhythmic properties.”
“This early discrimination led us to wonder when children’s sensitivity to the rhythmic properties of language emerges, including whether it may in fact emerge before birth.”
“Fetuses can hear things, including speech, in the womb. It’s muffled, like the adults talking in a ‘Peanuts’ cartoon, but the rhythm of the language should be preserved and available for the fetus to hear, even though the speech is muffled.”
“There was already a study that suggested fetuses could discriminate between different types of language, based on rhythmic patterns, but none using a magnetocardiogram.”
“The previous study used ultrasound to see whether fetuses recognized changes in language by measuring changes in fetal heart rate,” Dr. Minai said.
“The speech sounds that were presented to the fetus in the two different languages were spoken by two different people in that study. They found that the fetuses were sensitive to the change in speech sounds, but it was not clear if the fetuses were sensitive to the differences in language or the differences in speaker, so we wanted to control for that factor by having the speech sounds in the two languages spoken by the same person.”
Using a device called a fetal biomagnetometer, Dr. Minai and co-authors measured changes in fetal heart rate to assess discrimination of two rhythmically different languages (English and Japanese).
“The fetal biomagnetometer fits over the maternal abdomen and detects tiny magnetic fields that surround electrical currents from the maternal and fetal bodies. That includes heartbeats, breathing and other body movements,” said co-author Dr. Kathleen Gustafson, also from the University of Kansas.
“The device is more sensitive than ultrasound to the beat-to-beat changes in heart rate.”
“Obviously, the heart doesn’t hear, so if the baby responds to the language change by altering heart rate, the response would be directed by the brain.”
The study involved 24 American mothers-to-be (mean gestational age=35.5 weeks).
“Two-minute passages in English and Japanese were read by the same female bilingual speaker,” the authors said.
“Fetal magnetocardiography was recorded while the participants were presented first with passage 1, a passage in English, and then, following an 18 min interval, with passage 2, either a different passage in English or in Japanese.”
The fetal heart rates changed when they heard the unfamiliar, rhythmically distinct language (Japanese) after having heard a passage of English speech, while their heart rates did not change when they were presented with a second passage of English instead of a passage in Japanese.
“The fetal brain is developing rapidly and forming networks,” Dr. Gustafson explained.
“The intrauterine environment is a noisy place. The fetus is exposed to maternal gut sounds, her heartbeats and voice, as well as external sounds. Without exposure to sound, the auditory cortex wouldn’t get enough stimulation to develop properly.”
“This study gives evidence that some of that development is linked to language.”
“These results suggest that language development may indeed start in utero,” Dr. Minai added.
“Fetuses are tuning their ears to the language they are going to acquire even before they are born, based on the speech signals available to them in utero. Pre-natal sensitivity to the rhythmic properties of language may provide children with one of the very first building blocks in acquiring language.”
“We think it is an extremely exciting finding for basic science research on language. We can also see the potential for this finding to apply to other fields.”
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Utako Minai et al. 2017. Fetal rhythm-based language discrimination: a biomagnetometry study. NeuroReport, in press; doi: 10.1097/WNR.0000000000000794
