We investigated the effects of facial similarity between users and embodied agents under different experimental conditions. Sixty-four undergraduates interacted with two different embodied agents: in one case the agent was designed to look somewhat similar to the user, and in the other case the agent was designed to look dissimilar. We varied between subjects how helpful the agent was for a given task. Results showed that the facial similarity manipulation sometimes affected participants' responses, even though they did not consciously detect the similarity. Specifically, when the agent was helpful, facial similarity increased participantsi ratings of involvement. However, when exposed to unhelpful agents, male participants had negative responses to the similar-looking agent compared to the dissimilar one. These results suggest that using facially similar embodied agents has a potential large downside if that embodied agent is perceived to be unhelpful.

In the near future, human-like social robots will become indispensable for providing support in various social tasks, in particular for healthcare (e.g., assistance, coaching). The perception of realism, in particular human-like features, can help facilitate mediated social interaction. The current study investigated the effects of form realism on engagement with and use intentions of social robot embodiments. We have defined (perceived) form realism as the result of the appraisal of features that are perceived as realistic contrasted with those appraised as unrealistic. To test the effects of form realism, we applied the model of interactively perceiving and experiencing fictional characters (I-PEFiC). I-PEFiC explains how users respond to interactive, fictional, humanoid characters, on social robots. In a within-subjects design, participants (N = 29; \(M_{age}\) = 28.8 years, age range 18–56 years) interacted with three different robots built from LEGO Mindstorms, which differed in their degree of designed form realism. Each robot presented itself as a physiotherapy assistant and requested the participant to do several exercises. Results of a structured questionnaire indicated that form realism only played a modest role in the perception of electro-mechanical robots. Instead, the perception of affordances appeared to be crucial for determining engagement and intentions to use social robots.