In the Sally-Anne test, a child watches as Sally takes a marble and hides it in her basket. She then "leaves" the room and goes for a walk. While she is away, Anne takes the marble out of Sally’s basket and puts it in her own basket. When Sally returns the child is asked "Where will Sally look for her marble?" To pass, the child must recognize that Sally has not seen Anne move the marble, although the child herself has, and therefore should predict that Anne will look for it in the box where Anne left it. This folk psychology of reasoning about one another’s mental states is known as ‘Theory of Mind’. While most humans six and older have this capability it is extraordinarily difficult for computers to replicate this form of recursive reasoning about hidden states. In the DARPA ASIST project Prof. Mike Lewis and fellow researchers are not only attempting to reason about a single actor’s mental states but about that of an entire team including recursive beliefs about one other’s beliefs.