A new study has provided the first evidence that infants as young as 15 months can identify objects they have learnt about from listening to language even if the object remains hidden.
Developmental scientists from Northwestern University and Harvard University in the US reported their findings in PLOS One on 23 April 2025.
They said their study provided new insight for the developmental origins of human capacity to learn about things that are not perceptually present. It began to address how, and how early, the human mind can create mental representations of objects and events never witnessed directly.
It highlighted the power of language in infants’ daily lives, they said. In listening to conversations and book-reading, infants often heard words that they did not yet understand, and that they could not ‘map’ immediately to an object or event, the researchers said.
Their results showed that by 15 months, infants spontaneously used the linguistic context in which a new word occurred to build a gist of its meaning that supported subsequent learning.
Professor Sandra Waxman, the study’s senior author, said many people believed that success in word learning required the infant to ‘map’ a new word to an object that is physically present (e.g., “Look at the kumquat”).
“But in the natural course of a day, it is very common for us – and for infants – to hear words when the objects to which they refer to are not available to our immediate perception,” she told Northwestern University.
“We’re asking whether infants, too, can use the conversational contexts in which a word occurs to begin to learn their meaning.”
Waxman is the Louis W. Menk Professor of Psychology, director of the Infant and Child Development Center and an Institute for Policy Research Fellow at Northwestern. The study’s co-author is Dr Elena Luchkina, a former postdoctoral fellow at Northwestern, now a research scientist at Harvard.
They engaged 134 infants, 67 each at 12 months and 15 months in a three-part task. They presented infants with words they understood, paired with an image of the object to which it referred such as an apple, banana and grapes.
Next, infants heard a new word while the image of the novel object such as a kumquat was hidden from their view.
Finally, two novel objects appeared – a kumquat and a whisk – and infants were asked, “where is the kumquat?”
Fifteen-month-olds, but not 12-month-olds, looked longer at the fruit than the whisk. Although they had never seen any object paired with that novel word, 15-month-olds used the context clues to identify which object was most likely to be the one to which the novel word referred.
“The study shows that even babies who are just beginning to say their first words learn from the language they hear, even if the objects or events being discussed are not present,” Prof Waxman said on the Northwestern University website.
“Babies take in what they hear, and even if no object is present, they form a mental representation, or ‘gist’ of the new word’s meaning, one that is strong enough for them to use later when its referent object does appear.”
She suggested that at 12 months, infants may not yet know enough of the familiar words they heard in the context to begin to form a gist of the new word’s meaning.
