“I don’t know”: Ignorance and question-asking as engines for cognitive development 

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 nonverbal 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. 

Paul Harris is a developmental psychologist with interests in the development of cognition, emotion and imagination. For many years, he taught at Oxford University where he was a Professor of Developmental Psychology and a Fellow of St John’s College. In 2001, he moved to Harvard University where he holds the Victor S. Thomas Professorship in the Graduate School of Education. His latest book is: ‘Trusting what you’re told: How children learn from others’ (Harvard University Press, 2012).