Psychology Distinguished Lecture, Dr. Paul Harris, Harvard University

Children often acquire information by listening to other people. However, the extent to which children understand this process of information transmission and actively exploit it to fill gaps in their knowledge has not been systematically investigated. I review evidence that toddlers exhibit various expressive behaviors when faced with knowledge gaps. They look toward an available adult, they convey ignorance via non-verbal gestures (flips/shrugs) and increasingly produce verbal acknowledgements of ignorance (“I don’t know”). They also produce comments and questions about what their interlocutors might know. Nevertheless, children are slow to empirically check what an interlocutor claims even when it runs counter to their own intuitions.