What types of learning or reasoning are involved in forming a new communication system? To answer this question, this paper presents a computational model for forming a new communication system. The model was developed with ACT-R (Adaptive Control of Thought-Rational). In the model, two agents autonomously assign their roles to themselves. Agents also posses general learning mechanisms implemented in ACT-R. By incorporating imitative learning into these general learning mechanisms, this paper studies the role of imitation in the process of forming a new communication system. Finally, we compared the proposed model against a human experiment. The results of the simulation indicate that through imitation, after a short period of interaction, an isomorphic system is created. The result of the simulation also suggests the existence of imitation in the process of forming a human communication system.