This paper deals with simulations of real-time interactive character behavior. The underlying idea is to take into account principles from cognitive science, in particular, the human ability to anticipate and simulate the world behavior. For that purpose, we propose a conceptual framework where the entity possesses an autonomous world of simulation within simulation, in which it can simulate itself (with its own model of behavior) and the environment (with an abstract representation, which can be learnt, of the other entities behaviors). This principle is illustrated by the development of an artificial juggler, which predicts the motion of balls in the air and uses its predictions to coordinate its own behavior while juggling. Thanks to this model it is possible to add a human user to launch balls that the virtual juggler can catch whilst juggling. Copyright © 2011 John Wiley & Sons, Ltd.