Blinking is a small, often overlooked action in humans; however, scientists believe that integrating this behavior into robots holds significant importance.
In a laboratory at the Italian Institute of Technology in Genoa, BBC reporter Christine Ro sits across from a charming robot named iCub. Both of them tap sticks on a separate box in time with a light.
“This is the first time I’ve drummed along with a robot. I’m observing the robot, and I know it is observing me too,” Ro shared with BBC.
This drumming experiment is designed to test how a robot performing similar tasks affects human behavior. It is one of many experiments on human-robot interaction conducted by the CONTACT research group at the Italian Institute of Technology.
Ro’s gaze is drawn to iCub’s pale, heavy eyelids. She recalls the attention-grabbing noise each time the robot blinks after a few seconds. With its large eyes, iCub’s gaze is quite captivating.
“Although blinking is often thought to be merely a physiological reflex related to protecting and lubricating the eyes, it also plays a crucial role in interpersonal interaction,” said Helena Kiilavuori, a psychologist at the University of Tampere in Finland.
Signals
According to the BBC, humans blink to convey attention and emotions. As a form of non-verbal communication, this action reflects various things we may not be consciously aware of, such as who should continue speaking in a conversation.
Blinking is one of many social signals that humans continuously exchange, often without being aware of them. As a result, robot manufacturers have studied both the physical characteristics and psychological aspects of blinking behavior to understand why integrating this behavior into robots could be beneficial.
“Since blinking serves many important functions in human behavior, it can be assumed that a robot blinking would significantly enhance the perception of similarity. This could facilitate interaction between humans and robots,” Kiilavuori noted.
iCub – robot of the CONTACT research group at the Italian Institute of Technology. (Photo: BBC).
Indeed, the CONTACT group’s research with 13-year-old children and adults in Italy, published on Research Gate, shows that both groups preferred robots that could blink. Alessandra Sciutti, the lead researcher, pointed out that a robot that does not blink could make some people feel uncomfortable due to the feeling of being stared at.
People also believe that the more naturally a robot blinks, the smarter it appears. Intelligence plays a significant role in situations where humans rely on robots to gather information, such as in train stations.
However, despite the many benefits, integrating natural blinking capability into robots presents a technical challenge.
“Blinking is one of the most delicate movements in humans, so designing mechanisms to mimic this movement requires advanced technology, such as high-precision motors,” Kiilavuori explained.
“For example, robot manufacturers at Engineered Arts use expensive aerospace-grade motors and design their own control electronics,” she added.
David Hanson, founder of Hanson Robotics, also noted: “The speed of the motors that move the eyelids during blinking is indeed a challenge. Making the shape of the eye look natural when blinking while reducing friction between the eyelid and the artificial eye surface is also very difficult.”
Another issue is the trade-off between the speed and sound of the motors. According to Francesco Rea, a senior technician of the CONTACT group, iCub could use a quieter motor to reduce the noise when blinking, but the slower speed makes the robot appear sleepy.
Slow blinking also risks losing visual information because iCub’s camera is located behind its eyelids. “Missing 2 frames isn’t a big deal, but missing 10 frames would be a problem,” Rea stated.
Meanwhile, Kiilavuori added, “Another challenge is the precise timing of the blink.” This action can change based on different emotional states, for instance, a person may blink faster or slower when lying.
“Any timing discrepancy in a given context could make the robot appear odd and unsettling,” she remarked.
Opportunities
At Disney Research, robot manufacturers have collaborated with animators to develop a research prototype for realistic robot eye movements, aiming to design an expressive gaze system that allows filmmakers to easily control and convey subtle emotions.
With factors such as the arc of eyelid movement, “we can separate these individual behaviors, allowing us to focus on correcting aspects and small details,” said James Kennedy, a research scientist at Disney Research.
Making robots blink naturally like humans is a challenge. (Photo: BBC).
The Disney Research team has patented a sensor and control system for robot eye movements, including software that processes images captured by cameras in the robot’s chest and generates control signals for movements such as opening and closing eyelids.
Kennedy stated that the research is still experimental and has not yet been applied in Disney’s theme parks. “The goal is to select a single social signal and develop it as best as possible to create realistic movements and behaviors, thereby providing a foundation for human interaction,” he explained.
However, another common challenge is synchronizing humanoid robots’ blinking patterns with those of humans during conversations. This remains an intriguing problem for many robot manufacturers.
According to the BBC, blinking is just a small example of the many complex behaviors that make the interaction capabilities of robots appear less than truly natural, contrary to the exaggerated claims about the similarities between robots and humans.
In attempting to recreate such a small and often underestimated mechanism like blinking, we truly understand how complex and sophisticated it is. “And that presents a wonderful opportunity for us to explore and innovate,” Kennedy shared.