The Effect of a Humanoid Robot?s Emotional Behaviors on Users? Emotional Responses: Evidence from Pupillometry and Electroencephalography Measures

The design of humanoid robots? emotional behaviors has attracted many scholars? attention. However, users? emotional responses to humanoid robots? emotional behaviors which differ from robots? traditional behaviors remain well understood. This study aims to investigate the effect of a humanoid robot?s emotional behaviors on users? emotional responses using subjective reporting, pupillometry, and electroencephalography. Five categories of the humanoid robot?s emotional behaviors expressing joy, fear, neutral, sadness, or anger were designed, selected, and presented to users. Results show that users have a significant positive emotional response to the humanoid robot?s joy behavior and a significant negative emotional response to the humanoid robot?s sadness behavior, indicated by the metrics of reported valence and arousal, pupil diameter, frontal middle relative theta power, and frontal alpha asymmetry score. The results suggest that humanoid robot?s emotional behaviors can evocate users? significant emotional response. The evocation might relate to the recognition of these emotional behaviors. In addition, the study provides a multimodal physiological method of evaluating users? emotional responses to the humanoid robot?s emotional behaviors.