Researchers have suggested that even before infants begin to talk in sentences, they pay careful attention to the way a new word is used in conversations.
And thus they learn new words from the information in sentences. For example, if you take an infant to the zoo and say, "Look at the gorilla" while pointing at the cage, the infant may not know what exactly is being referred to. However, if you say, "Look! The gorilla is eating," the infant can use the word that they do know-"eating"-to conclude that "gorilla" must refer to the animal and not, for example, the swing she is sitting on.
The zoo scenario mirrors the method the researchers used for their experiment. First, infants at ages 15 and 19 months were shown several pairs of pictures on a large screen.
Each pair included one new kind of animal and a non-living object. Next, the objects disappeared from view and infants overheard a conversation that included a new word, "blick." Finally, the two objects re-appeared, and infants heard, for example, "Look at the blick."
Lead author Brock Ferguson, a doctoral candidate in psychology at Northwestern, said that after overhearing this new word in conversation, infants who hear a helpful sentence such as 'the blick is eating' should look more towards the animal than the other, non-living object.
He said that they show that by 19 months, they do just that. In contrast, if infants heard the new word in an unhelpful sentence such as 'the blick is over here' during the conversation, they don't focus specifically on the animal because, after all, in this kind of sentence, 'blick' could mean anything.
The researchers said infants usually hear a new word for the first time under much more natural and complex circumstances such as the zoo example described.