Language

How babies find words in a stream of sound: transitional probabilities

Rows of syllable chips with tall green bars inside words and short red bars at each word boundary, showing transitional probability dips
30seconds
The 30-second version

Babies hear speech as one unbroken smear, with no gaps between words, yet somehow they start picking out words long before they can say one.

One clue sits in the sound itself: inside a word, one syllable reliably follows another, while across a word boundary almost anything can come next. In 1996, eight-month-olds heard only two minutes of nonsense syllables and picked this up. Listen to the same stream yourself, watch the transitional probabilities appear, and cut it into words with a slider.

Deep dive · 4 min
Deep dive · 4 min

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