Rhesus monkeys accept a naturalistic-looking monkey avatar as a member of the same species and encounter it with their species-specific facial expressions. They ignore unrealistic avatars.
If you want to learn more about the social interaction of monkeys, you have to present them facial expressions of their fellow members under controlled conditions, it is not possible with videos of real monkeys alone.
Therefore neuroscientists from the research groups of Professor Peter Thier and Professor Martin Giese from the HIH and the Werner Reichardt Center for Integrative Neurosciences at the University of Tübingen have developed a monkey avatar that meets these requirements.