Health sciences students often practice and are evaluated on interview and exam skills by working with standardized patients (people that role play having a disease or condition). However, standardized patients do not exist for certain vulnerable populations such as children and the intellectually disabled. As a result, students receive little to no exposure to vulnerable populations before becoming working professionals. To address this problem and thereby increase exposure to vulnerable populations, we propose using virtual humans to simulate members of vulnerable populations. We created a mixed reality pediatric patient that allowed students to practice pediatric developmental exams. Practicing several exams is necessary for students to understand how to properly interact with and correctly assess a variety of children. Practice also increases a student's confidence in performing the exam. Effective practice requires students to treat the virtual child realistically. Treating the child realistically might be affected by how the student and virtual child physically interact, so we created two object interaction interfaces - a natural interface and a mouse-based interface. We tested the complete mixed reality exam and also compared the two object interaction interfaces in a within-subjects user study with 22 participants. Our results showed that the participants accepted the virtual child as a child and treated it realistically. Participants also preferred the natural interface, but the interface did not affect how realistically participants treated the virtual child.

Mixed reality (MR) combines virtual elements with the real, physical world. Virtual elements can be more dynamic - easily moving around or changing appearance. Physical elements are more static but improve immersion and presence. The combination of the two creates dynamic, immersive MR environments. However, individual entities in MR environments, e.g. an object or a character, are typically either purely physical or purely virtual. We propose using both virtual and physical elements in a hybrid virtual-physical entity. We implemented this idea with a hybrid virtual human and ran several user studies. These studies helped us develop guidelines for implementing hybrid entities.

The concepts of immersion and presence focus on the environment in a virtual environment. We instead focus on embodied conversational agents (ECAs). ECAs occupy the virtual environment as interactive partners. We propose that the ECA analogues of immersion and presence are physicality and social presence. We performed a study to determine the effect of an ECA's physicality on social presence and eliciting realistic behavior from the user. The results showed that increasing physicality can elicit realistic behavior and increase social presence but there was also an interaction effect with plausibility.