This study aimed to investigate the joint contributions of appearance and type of mind attributed to agents on the uncanny valley (UV) effect. We conducted an experiment in an ecologically valid virtual reality environment, where participants engaged in a conversational game. The setup was intended to increase the validity of the results and provide a more comprehensive understanding of the UV effect. The study used a \(2\times2\) experimental design, manipulating both the agent’s appearance (robot or human) and the identity behind the character (artificial intelligence or a user’s mind). The final sample consisted of 116 participants. Self-reported eeriness and likability, as well as, electrodermal and heart activities were measured. It was found that the appearance of the agent was crucial in determining users’ perceptions of humanlikeness and feelings of eeriness, but the type of mind attributed to the agent did not significantly affect feelings of eeriness. Additionally, the interaction between appearance and type of mind attributed to the agent influenced behavioral realism, which, in turn, affected likability. People perceive other users with more humanlike avatars and artificial intelligence presented as robots as more realistic and, thus, more likable. We discuss the possibility that difficulties with emotion recognition and feelings of eeriness are attributed to the inability to recognize emotion, which we identified as a possible cause for uncanny ratings. Our results suggest that cues related to the ability to experience do not increase feelings of eeriness themselves, but rather a violation of the expectancy regarding these cues increases feelings of eeriness. Our study provides insight into the factors that contribute to human-robot interactions and highlights the importance of appearance in designing effective and likable artificial agents.
