Research
A new study in Science Robotics shows that people become more suspicious of a humanoid robot that makes errors, especially when the robot is an expressive conversation partner. The finding matters because it challenges the simple assumption that social cues like gestures and eye contact always build trust in human-robot interaction.
The researchers, from Drexel University, the United States Air Force Academy, and George Mason University, had 50 people hold conversations and make joint decisions with the commercial humanoid robot Pepper, which is designed to be expressive and recognize emotions. Sometimes the robot gave sound advice; sometimes it made conversational mistakes, interrupting people or pushing illogical suggestions. For some participants, the robot was animated, using gestures, eye contact and nods; for others, it stayed motionless.
When people interacted with an expressive robot that violated interaction norms, their oxytocin levels increased.
The team measured four things: brain activity, levels of the hormone oxytocin, self-reported trust, and observations of the robot’s influence on participants’ decisions. They found that when people interacted with an expressive robot that violated interaction norms, their oxytocin levels increased. Oxytocin is popularly known as the “love hormone” for its role in social bonding, so the straightforward prediction is that it declines when a partner disappoints you. Instead, the higher a person’s oxytocin during an expressive robot’s errors, the less they trusted the robot and the less often they took its advice. The hormone was tracking with suspicion, not affection.
Errors damaged trust and diminished the robot’s influence on decisions, particularly when the robot was expressive. The study highlights that expressiveness can backfire when a robot behaves awkwardly, and it suggests that physiological markers like oxytocin can reveal the subtle dynamics of trust in human-robot interaction.
Source: Robohub