Linnunsalo, S., et al. (2024).
Biological Psychology, 108858.
Abstract
Eye contact with a human and with a humanoid robot elicits attention- and affect-related psychophysiological responses. However, these responses have mostly been studied in adults, leaving their developmental origin poorly understood. In this study, 114 infants (6–8 months old) viewed direct and averted gaze directions of a live human and an embodied humanoid robot while their heart rate deceleration (attention orienting), skin conductance (affective arousal), and facial muscle activity (affective valence) were measured. In addition, a non-humanoid object (a vase) was used as a control stimulus. Infants’ attention orienting was stronger to averted versus direct gaze of a human and a robot, but indifferent to the averted versus direct orientation of the non-humanoid object. Moreover, infants’ attention orienting was equally intensive toward a human and a robot, but less intensive toward a non-humanoid object. Affective arousal was insensitive to gaze direction and did not differ between the human, the robot, and the non-humanoid object. Facial muscle responses showed sensitivity to the gaze direction of a human and of a robot but not to the orientation of the non-humanoid object. These results suggest that infants recognize the attentional and affective/affiliative significance not only in a human’s gaze but also in a robot’s gaze.
Highlights
• We investigated infants’ psychophysiological responses to eye contact.
• Infants viewed direct and averted gaze of a live human and of a humanoid robot.
• Heart rate deceleration, skin conductance and facial electromyography were measured.
• Responses were sensitive to the gaze direction of a human and of a humanoid robot.
Here are some thoughts:
This research explores how infants aged 6 to 8 months respond to eye contact from both humans and humanoid robots, highlighting the importance of eye contact in early social development. The study found that infants recognize the social significance of eye contact not only from human faces but also from humanoid robots, indicating an early ability to engage socially. Interestingly, while infants looked longer at both the human and robot stimuli compared to a non-interactive vase, their looking times did not differ between direct and averted gazes, suggesting they were equally engaged by both.
The researchers observed that infants’ heart rates slowed more in response to averted gazes, which may signal an emerging capacity for joint attention—an essential component of social skills. Additionally, facial muscle activity revealed that infants’ cheek muscles, associated with smiling, were more active during direct eye contact, while eyebrow muscles linked to concentration showed increased activity with averted gazes. This pattern suggests that infants may interpret eye contact as a positive social cue while simultaneously focusing on where others are looking.
Involving 114 infants, the study presented them with a human, a humanoid robot named Nao, and a vase, using live stimuli to enhance realism. Researchers recorded infants’ reactions through eye-tracking, heart rate measurements, and facial muscle activity. The findings indicated that infants respond similarly to the eye contact of humanoid robots and humans, suggesting that even at a young age, they may interpret robotic social cues similarly to human interactions. However, the study also noted that emotional arousal related to eye contact might develop later as infants gain more social experience.
Despite these insights, the study had limitations, particularly concerning the use of a vase as a control stimulus, which lacked eyes. This raises questions about whether infants' responses were driven solely by the robots' human-like features or their social behaviors. These findings are significant as humanoid robots become increasingly integrated into caregiving and educational settings, underscoring the need to understand how infants perceive and interact with these artificial agents.
