Researchers, in Multimodal Interaction Systems, devote substantial effort to the integration of external stimulus and signal, to the internal representation of this information and to the response generation. Nevertheless, they focus less effort on how to integrate studies in Cognitive Psychology regarding the human interaction subject. Therefore, it becomes interesting to evaluate the assumption that a dialog model based on known human factors should outcome better perception of the interaction process by the users. This paper presents an experimental approach to implement multimodal interaction systems where the main innovative aspect is related to the dialogue managing, that is based on the working memory model proposed by Baddeley and Hitch. A computational model was proposed and two different prototypes were built. The obtained results were found to be positive and it indicates relevant flexibility aspects together with an encouraging feedback from users.