Dissertation

TEXT PAULA HEINO, PHOTO VESA-MATTI VÄÄRÄ

Babies learn as they sleep

Newborn babies can learn to discriminate speech sounds even in their sleep. They cannot, however, yet distinguish between natural and synthetic sounds. Learning while sleeping seems to be particularly effective in infancy, when sleep is decidedly different than it is in adulthood.

Olga Martynova worked on her dissertation in Turku for 3 years. “I’m going back to St. Petersburg now. I'm thinking of becoming a qualified psychologist, but the future is still open,” says Olga, who has a husband and a two-year- old son in the city, which celebrates its tricentenary.

This last summer, Olga Martynova, M.Sc., completed her doctoral dissertation in psychology at the University of Turku. She had previously studied biology at St. Petersburg State University in Russia.

Martynova conducted her research at the Centre for Cognitive Neuroscience in cooperation with Turku University Central Hospital. The hospital provided a laboratory for the research team in its neonatal unit. Permission to study the newborn babies was obtained from the parents. As part of the research, babies less than a week old had a small electrode cap placed on their head for a few hours in order to record changes in their EEG. The newborns were divided into groups, and certain sounds were repeatedly played to some of them at night when they were sleeping. This stage of the research provided a reliable database and took about two months to complete. In all, the study included 80 newborn babies

Initially, Martynova began her research in Docent Marie Cheour's team, but when Cheour moved to the United States to work as a researcher, Professor Heikki Hämäläinen became Martynova's advisor. The results of the study were reported in Nature.

A RELIABLE METHOD

From the standpoint of speech and language acquisition theories, it is vital to know how newborn babies discriminate between sounds and learn speech. The aim of Martynova’s dissertation was to study whether newborn babies and adults discriminate in different ways between speech sounds and whether newborn babies can also discriminate between sounds while sleeping. Research on speech acquisition is important, so that in the future speech impediments in young children can be treated.

The method used in the study is called mismatch negativity (MMN). This can be used as a reliable tool in research on newborn speech discrimination in all sleep stages as well as when the baby is awake. Mismatch negativity is an event-related potential (ERP) that provides an objective means of evaluating auditory discrimination.

LEARNING BY PRACTICE

Martynova’s doctoral dissertation demonstrates that sleeping newborn babies can be ‘trained’ to discriminate between speech sounds. In addition, the results show that newborn babies, unlike adults, probably process natural and synthetic sounds similarly. On the basis of the results, one can assume that newborn babies not only learn speech, but also hear other ambient sounds in their sleep.

In conclusion, the infant brain is not yet so specialised that it can process speech in the same way as the adult brain, but it begins to practise this effectively soon after birth.

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