'Clap your hands' or 'take your hands'? One-year-olds distinguish between frequent and infrequent multiword phrases.

Although words are often described as the basic building blocks of language, there is growing evidence that multiword sequences also play an integral role in language learning and processing. It is not known, however, whether children become sensitive to multiword information at an age when they are still building knowledge of individual words. Using a central fixation paradigm, the present study examined whether infants between 11 and 12 months (N = 36) distinguish between three-word sequences (trigrams) with similar substring frequencies but different multiword frequency in infant-directed speech (e.g., high frequency: 'clap your hands' vs. low frequency: 'take your hands'). Infants looked significantly longer at frequent trigrams compared to infrequent ones. This provides the first evidence that infants at the cusp of one-word production are already sensitive to the frequency of multiword sequences, and suggests they represent linguistic units of varying sizes from early on, raising the need to evaluate knowledge of both words and larger sequences during development.