Lost in Seattle

Ray’s school sometimes hosts “Parent Education Evenings” whereupon the mommies and daddies assemble to discuss topics or listen to lectures about some aspect of child education.

Last night’s event was fascinating. It featured Dr. Patricia Kuhl who is the Co-Director of the Institute for Learning and Brain Sciences at the University of Washington, and who studies early language and brain development.

Dr. Kuhl discussed a recent experiment she conducted that was designed to determine how many distinct phonemes an infant can detect. Each language, she explained, uses only a small subset of all the possible sounds humans can utter. Infant brains use a sort of statistical analysis on all the speech data they take in and their brains start to develop structures to understand and differentiate only the most frequently-occurring sounds. By around 12 months of age, babies have largely become “language specialists” and begin to lose their ability to differentiate sounds from foreign languages.

The experiment itself involved placing an infant near a loudspeaker that was emitting a repetitive stream of syllables — for example, “la, la, la, la.” The baby was distracted by a researcher opposite the speaker. After a few minutes, the speaker changed to emit a different sound — e.g. “ra, ra, ra, ra” — and after a moment, lights illuminated the inside of the speaker and revealed a mechanical monkey playing cymbals (which, of course, I would find absolutely terrifying). This was repeated, and shortly the infant would learn to look behind her at the speaker whenever the sound changed so she could see the funny monkey.

The experiment demonstrated that infants can detect differences between virtually all sounds, but as they age they gradually lose the ability to differentiate sounds that are not common to their native language. Dr. Kuhl referred to the “She-She Test,” which used two tonally-distinct phonemes from Mandarin that even she couldn’t tell apart but which her Chinese research assistants insisted were as distinct as “ra” and “la” to their ears. Babies raised in English-speaking households can initially tell the difference between “shé” and “shè”, but lose the ability over time. Babies raised in Mandarin-speaking households can initially tell the difference between “ra” and “la,” but gradually lose that ability over time as well.

Interestingly, Dr. Kuhl went on to demonstrate that exposing a baby from an English-speaking household to just twelve 20-minute sessions of someone speaking to them in Mandarin improved the baby’s ability to differentiate Mandarin phonemes almost to the level of infants raised in Mandarin-speaking households, and vice versa.

What I found most fascinating, however, was that she conducted the same experiment replacing the actual foreign-language-speaking human with a video or audio recording of the same person saying roughly the same things, and discovered that babies’ abilities did not improve at all compared to a control group. In other words, kids acquire language from personal interaction and speech but cannot do so via technology-mediated means (i.e. television or audiotapes).

So much for Muzzy.