Language discrimination by newborns: Teasing apart phonotactic, rhythmic, and intonational cues

Speech rhythm has long been claimed to be a useful bootstrapping cue in the very first steps of language acquisition. Previous studies have suggested that newborn infants do categorize varieties of speech rhythm, as demonstrated by their ability to discriminate between certain languages. However, the existing evidence is not unequivocal: in previous studies, stimuli discriminated by newborns always contained additional speech cues on top of rhythm. Here, we conducted a series of experiments assessing discrimination between Dutch and Japanese by newborn infants, using a speech resynthesis technique to progressively degrade non-rhythmical properties of the sentences. When the stimuli are resynthesized using identical phonemes and artificial intonation contours for the two languages, thereby preserving only their rhythmic and broad phonotactic structure, newborns still seem to be able to discriminate between the two languages, but the effect is weaker than when intonation is present. This leaves open the possibility that the temporal correlation between intonational and rhythmic cues might actually facilitate the processing of speech rhythm. Key-words: newborn speech perception language discrimination rhythm intonation prosody bootstrapping. Language acquisition is a field notorious for its bootstrapping problems: in essence, it seems impossible to explain how each component of language is learnt without appealing to previous knowledge of other components. How does the child learn syntax? By relying on his/her knowledge of words, their meaning, and the meaning of whole sentences, as revealed by observation (this is semantic bootstrapping; Pinker, 1984). But how does the child learn the meaning of words? You have to assume some notions of syntax (this is syntactic bootstrapping; Gleitman, 1990). These apparent paradoxes have raised interest in the study of the raw input available to the child, i.e., the speech signal, and of how much information can be extracted thereof. In this line, Gleitman and Wanner (1982) had already long ago suggested that prosody (rhythm, intonation) might play an important role in the acquisition of syntax (this was prosodic bootstrapping). Prosody has also been shown to be an impor