Infants attend to speech, even before birth, preferring what they heard in utero over another language. In the first months, they can identify certain sounds as the same. (Other species also display categorical perception of sounds.) By 7 to 8 months, infants can identify recurring sequencies of both nonsense syllables and real words. Measures used include high-amplitude sucking, head-turn preferences, and visual fixation. In segmenting speech, infants face two problems: variation in speakers’ word uses, and which sounds to group as the same. They can also recognize a few words. By 9 to 10 months, infants attend more to distinctions in the ambient language than distinctions outside that language, and appear sensitive to legal clusters of sounds that begin and end syllables. They also prefer the prosodic stress patterns of the ambient language and so can use multiple cues to possible word-boundaries. By age three and later, children manage to recognize words even when spoken in another dialect or with a foreign accent. Their recognition of words at age three shows their representations in memory are adultlike, and not based on their own productions. They store representations of words in memory for recognizing words from other speakers, and as targets for their own production.

Infants attend to speech, even before birth, preferring what they heard in utero over another language. In the first months, they can identify certain sounds as the same. (Other species also display categorical perception of sounds.) By 7 to 8 months, infants can identify recurring sequencies of both nonsense syllables and real words. Measures used include high-amplitude sucking, head-turn preferences, and visual fixation. In segmenting speech, infants face two problems: variation in speakers’ word uses, and which sounds to group as the same. They can also recognize a few words. By 9 to 10 months, infants attend more to distinctions in the ambient language than distinctions outside that language, and appear sensitive to legal clusters of sounds that begin and end syllables. They also prefer the prosodic stress patterns of the ambient language and so can use multiple cues to possible word-boundaries. By age three and later, children manage to recognize words even when spoken in another dialect or with a foreign accent. Their recognition of words at age three shows their representations in memory are adultlike, and not based on their own productions. They store representations of words in memory for recognizing words from other speakers, and as targets for their own production.