One of the most sophisticated abilities young children possess is recognizing the mental states of others.
From about the second year onward, infants and children can understand that other people's actions reflect invisible states like wanting, pretending, and believing. We call this commonsense ability, "theory of mind." We are interested in the nature of this early competence.
Naturally, there are limits on the sorts of mental state problems young children can solve. We are also interested in how these limitations change between infancy and four years of age and beyond. We devise simple tests of reasoning to probe the nature of these changes.