The development of a Shared Mental Model (SMM) between team members and effective communication of the shared knowledge have been found to improve teamwork performance. In human-IVA heterogeneous teams, the communication required to develop a SMM is difficult as each party belongs to different worlds (i.e. real and virtual). Moreover, humans may differ in how they produce and perceive communication acts according to their personality traits. The influence of IVA personality, exhibited via verbal and non-verbal communication, on collaboration and development of a SMM within a human-IVA team has not been previously studied. In this paper, we explore the impact of IVA's with two different combinations of personality traits, i.e. extraversion and agreeableness, on the development of a SMM with human teammates. Additionally, this study investigated the influence of the match in the two personality traits between IVAs and humans on the development of a SMM. The results showed that agreeable IVAs positively impacted on the development of taskwork and teamwork SMMs; whereas extraversion did not influence development of the SMM. Moreover, when collaborating humans and IVAs had matching agreeableness personality traits there was a positive influence on the SMM between them and better performance outcomes.