A meta-analysis of the impact of the inclusion and realism of human-like faces on user experiences in interfaces

The use of embodied agents, defined as visual human-like representations accompanying a computer interface, is becoming prevalent in applications ranging from educational software to advertisements. In the current work, we assimilate previous empirical studies which compare interfaces with visually embodied agents to interfaces without agents, both using an informal, descriptive technique based on experimental results (46 studies) as well as a formal statistical meta-analysis (25 studies). Results revealed significantly larger effect sizes when analyzing subjective responses (i.e., questionnaire ratings, interviews) than when analyzing behavioral responses such as task performance and memory. Furthermore, the effects of adding an agent to an interface are larger than the effects of animating an agent to behave more realistically. However, the overall effect sizes were quite small (e.g., across studies, adding a face to an interface only explains approximately 2.5% of the variance in results). We discuss the implications for both designers building interfaces as well as social scientists designing experiments to evaluate those interfaces.