This paper describes how certain forms of multimedia can be combined with the principles of a cognitive theory in order to improve human-computer interaction. An animated, speech-driven agent has been developed in order to simulate a human expert. However, the main focus of this research is on adapting a theory of human plausible reasoning in order to render the agent's interaction with the user more human-like, The agent uses this reasoning while watching the user "over the shoulder" so that it can decide on the advice that Jits the user better. The evaluation of the interface revealed that human-computer interaction can successfully be improved by the adaptation of such an animated, speech-driven agent, when it can reproduce human reasoning.