Effects of adapting to user pitch on rapport perception, behavior, and state with a social robotic learning companion

Social robots such as learning companions, therapeutic assistants, and tour guides are dependent on the challenging task of establishing a rapport with their users. People rarely communicate with just words alone; facial expressions, gaze, gesture, and prosodic cues like tone of voice and speaking rate combine to help individuals express their words and convey emotion. One way that individuals communicate a sense of connection with one another is entrainment, where interaction partners adapt their way of speaking, facial expressions, or gestures to each other; entrainment has been linked to trust, liking, and task success and is thought to be a vital phenomenon in how people build rapport. In this work, we introduce a social robot that combines multiple channels of rapport-building behavior, including forms of social dialog and prosodic entrainment. We explore how social dialog and entrainment contribute to both self-reported and behavioral rapport responses. We find prosodic adaptation enhances perceptions of social dialog, and that social dialog and entrainment combined build rapport. Individual differences indicated by gender mediate these social responses; an individual’s underlying rapport state, as indicated by their verbal rapport behavior, is exhibited and triggered differently depending on gender. These results have important repercussions for assessing and modeling a user’s social responses and designing adaptive social agents.