This paper presents a novel method for evaluating the impact of animated interface agents with affective and empathic behavior. While previous studies relied on questionnaires in order to assess the user’s overall experience with the interface agent, we will analyze users ’ physiological response (skin conductance and electromyography), which allows us to estimate affect-related user experiences on a moment-by-moment basis without interfering with the primary interaction task. As an interaction scenario, a card game has been implemented where the user plays against a virtual opponent. The findings of our study indicate that within a competitive gaming scenario, (i) the absence of the agent’s display of negative emotions is conceived as arousing or stress-inducing, and (ii) the valence of users ’ emotional response is congruent with the valence of the emotion expressed by the agent. Our results for skin conductance could also be reproduced by assuming a local rather than a global baseline.

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. Author Keywords Computer-mediated communication, quantitative methods, meta-analysis, embodied agents, realism. ACM Classification Keywords H5.m. Information interfaces and presentation (e.g., HCI):