In the false-beliefs task, children observe big bird leave a toy in one location and cookie monster move the toy to a different location while big bird is somewhere else. when asked where big bird will think the toy is located, children with a fully developed theory of mind are likely to say that

Big Bird will think the toy is where he left it.

Theory of mind or as known for short ToM is the capacity to characteristic mental states, convictions, aims, wants, feelings, information, and so forth, to one’s own self, and to others, and to comprehend that others have convictions, wants, aims, and points of view that are unique in relation to one's own.