Like human faces, infants are predisposed to pay attention to words. Now a new study shows that they learn concepts from them from a very early age. In the study, in which 46 three-month-old infants were shown a series of pictures of fish that were paired either with words (e.g., "Look at the toma!") or beeps (carefully matched to the words for tone and duration), those who heard the words subsequently showed signs of having formed the category “fish”, while those who heard the tones did not. Categorization was assumed when infants shown a picture of a new fish and a dinosaur side-by-side, looked longer at one picture than the other.
(2010). Categorization in 3- and 4-Month-Old Infants: An Advantage of Words Over Tones.
Child Development. 81(2), 472 - 479.