Non-verbal signals in HRI: Interference in human perception

Abstract

Non-verbal cues of communication can influence the human understanding of verbal signals in human-human communication. We present two illustrative experimental studies showing how non-verbal cues can both interfere and facilitate communication when passing amessage to a user in HRI. In the first study, participants found that the cues enabling them to discriminate between two conditions: permissive or authoritative robots were mainly verbal. The verbal message was however unchanged between these two conditions and in this case, non-verbal cues of communication (gestures, posture, voice tone and gaze) substituted the neutral verbal message. The second study highlights the fact that verbal and nonverbal communication can facilitate the understanding of messages when combined appropriately. This study is based on a Stroop task of identifying the colour of the LEDs of a robot while the robot says words that are either facilitating, neutral or disturbing for the participant. These two studies put into perspective the importance of understanding interrelations between non-verbal and verbal signals in HRI.