Primate social cognition involves the ability of group members to recognize and effectively communicate with each other. They do this through a variety of facial expressions, which can be studied using objective measurement tools that enable cross-species comparisons. Facial expressions provide information about the motivation of signalers and enable others to predict the behavior and intentions of group members. By comparing the form and function of facial expressions across species, general assumptions about the underlying emotional meaning of these signals can be deduced. Some chimpanzee facial expressions show a similar form and emotional meaning with human expressions.