What the [beep]? Six-month-olds link novel communicative signals to meaning

Over the first year, infants tune into the signals of their native language and begin to link them to meaning. Here, we ask whether infants, like adults, can also infer the communicative function of otherwise arbitrary signals (here, tone sequences) and link these to meaning as well. We examined 6-month-olds' object categorization in the context of sine-wave tones, a signal that fails to support categorization at any point during their first year. However, before the categorization task, we exposed infants to tones in one of two vignettes. In one, the tones were produced by an actor in a rich communicative exchange; in the other, infants heard the very same tones, but these were uncoupled from the actors' activity. Infants exposed to the communicative vignette successfully formed object categories in the subsequent test; those exposed to the non-communicative vignette failed, performing identically to infants with no prior exposure to this novel signal. This reveals in 6-month-old infants a remarkable flexibility in identifying which signals in the ambient environment are communicative and in linking these signals to core cognitive capacities including categorization.