A new study shows that "infant-directed speech," often called "parentese," the speech style parents use to talk to their babies, which has simpler grammar, higher and exaggerated pitch, and drawn-out vowels, is effective for infants to learn foreign language.
"Our research shows that parentese helps babies learn language," said Naja Ferjan Ramirez, a research scientist at the University of Washington (UW) Institute of Learning & Brain Sciences (I-LABS), about the study published this week in Mind, Brain, and Education, a quarterly peer-reviewed academic journal.
For years, scientists and parents have touted the benefits of introducing babies to two languages, as bilingual experience has shown to improve cognitive abilities, especially problem-solving. For infants raised in households where two languages are spoken, that bilingual learning happens almost effortlessly. But how can babies in monolingual households develop such skills?
In the new study, researchers developed a play-based, intensive, English-language method and curriculum and implementing it in four public infant-education centers in Madrid, Spain.
Sixteen UW undergraduates and recent graduates served as tutors, undergoing two weeks of training at I-LABS to learn the teaching method and curriculum before traveling to Spain. Based on years of I-LABS research on infant brain and language development, the method emphasizes social interaction, play, and high quality and quantity of language from the teachers.
The European country's extensive public education system enabled the researchers to enroll 280 infants and children from families of varying income levels.
Babies aged 7 to 33.5 months were given one hour of English sessions a day for 18 weeks, while a control group received the Madrid schools' standard bilingual program. Both groups of children were tested in Spanish and English at the start and end of the 18 weeks. The children also wore special vests outfitted with lightweight recorders that recorded their English learning. The recordings were analyzed to determine how many English words and phrases each child spoke.
The children who received the UW method showed rapid increases in English comprehension and production, and significantly outperformed the control group peers at all ages on all tests of English.
By the end of the 18-week program, the children in the UW program produced an average of 74 English words or phrases per child, per hour; children in the control group produced 13 English words or phrases per child, per hour.
The findings indicate that babies from monolingual homes can develop bilingual abilities at this early age, Ferjan Ramirez said. "With the right science-based approach that combines the features known to grow children's language, it is possible to give very young children the opportunity to start learning a second language, with only one hour of play per day in an early education setting."
Follow-up testing 18 weeks later showed the children had retained what they learned. The gains were similar between children attending the two schools serving predominantly low-income neighborhoods and the two serving mid-income areas, suggesting that wealth was not a significant factor in the infants' ability to learn a foreign language.
Children's native language, namely Spanish, continued to grow as they were learning English, and was not negatively affected by introducing a second language.
"Science indicates that babies' brains are the best learning machines ever created, and that infants' learning is time-sensitive. Their brains will never be better at learning a second language than they are between 0 and 3 years of age," said co-author Patricia Kuhl, co-director of I-LABS and a UW professor of speech and hearing sciences.
Kuhl believes that the results of the study have the potential to transform how early language instruction is approached in the United States and worldwide.