Northwestern University researchers have found how words impact babies’ cognition.

Three-month-olds were shown a series of pictures that were paired with made-up words or sounds. The babies that heard the words looked at similar images for a longer amount of time: They remembered the object.

“For infants as young as 3 months of age, words exert a special influence that supports the ability to form a category,” said Susan Hespos, one of the authors of the study, which was published in the March/April edition of Child Development. “These findings offer the earliest evidence to date for a link between words and object categories.”

Added co-author Sandra Waxman, “We suspect that human speech, and perhaps especially infant-directed speech, engenders in young infants a kind of attention to the surrounding objects that promotes categorization. We proposed that over time, this general attentional effect would become more refined, as infants begin to cull individual words from fluent speech, to distinguish among individual words and kinds of words, and to map those words to meaning.”