A Robot with Style: Can Robotic Attitudes Influence Human Actions?

The style of an action, i.e. the way it is performed, has a strong influence on interaction between humans. The same gesture has different consequences when it is performed aggressively or kindly, and humans are very sensitive to these subtle differences in others' behaviors. In this work we investigated how to endow a humanoid robot with behaviors expressing different vitality forms, by modulating robot action kinematics and voice intonation. Drawing inspiration from human voice and motion, we modified a passing action and a passing voice command performed by the robot to convey an aggressive or kind attitude. In a series of experiments we demonstrated that the humanoid was consistently perceived as aggressive or kind. Human behavior changed slightly in response to the different robot attitudes and was characterized by faster responses to robot utterances than to robot actions. The opportunity of humanoid behavior to express vitality enriches the array of nonverbal communication that can be exploited by the robots to foster seamless interaction. Such behavior might be crucial in emergency and in authoritative situations in which the robot should instinctively be perceived as assertive and in charge, as in case of police robots or teachers.