An uncanny game of trust: Social trustworthiness of robots inferred from subtle anthropomorphic facial cues

Modern android robots have begun to penetrate the social realm of humans. This study quantitatively probed the impact of anthropomorphic robot appearance on human social interpretation of robot facial expression. The “Uncanny Valley” theory describing the disturbing effect of imperfect human likenesses has been a dominant influence in discussions of human-robot social interaction, but measuring its effect on human social interactions with robots has been problematic. The present study addresses this issue by examining social responses of human participants to a series of digitally composed pictures of realistic robot faces that span a range from mechanical to human in appearance. Our first experiment provides evidence that an Uncanny Valley effect on social attractiveness is indeed a practical concern in the design of robots meant to interact socially with the lay public. In the second experiment, we employed game-theory research methods to measure the effect of subtle facial expressions in robots on human judgments of their trustworthiness as social counterparts. Our application of game-theory research methods to the study of human-robot interactions provides a model for such empirical measurement of human's social responses to android robots.