Pneumatically operated Nikola aids in the study of emotions

Researchers from the RIKEN Guardian Robot Project in Japan have created Nikola, an android child who demonstrates six basic emotions through a series of pneumatic actuators.

six emotional expressions assessed in the second experiment (Image: RIKEN)

The new study conducted by Wataru Sato, published in Frontiers in Psychology, tested how well people could identify six facial expressions — joy, sadness, fear, anger, surprise, and disgust — that were generated by moving artificial muscles on Nikola’s face. According to RIKEN, this is the first time that the quality of emotion expressed by androids has been tested and verified for these six emotions.

Inside Nikola’s face are 29 pneumatic actuators that control the movements of artificial muscles. Six other actuators control the movements of the head and the eyeball. Pneumatic actuators are controlled by air pressure, making movements quiet and smooth.

The team arranged the actuators according to the Facial Action Coding System (FACS), which has been widely used to study facial expressions. Previous research has identified many facial actions – such as “raising cheeks” and “puckering lips” – that include typical emotions such as happiness or disgust, and researchers have incorporated these action units into the design. by Nikola.


According to RIKEN, studies of emotions, particularly how people respond to emotions, have been problematic. It’s hard to do a properly controlled experiment with live people interacting, but looking at photos or videos of people is less natural and the reactions aren’t the same.

“The hope is that with androids like Nikola, we can have our cake and eat it too,” Sato said in a statement. “We can control every aspect of Nikola’s behavior, and at the same time study live interactions.”

A person certified in FACS notation was able to identify each unit of facial action, indicating that Nikola’s facial movements look exactly like those of a real human. A second test showed that audience members recognized the six prototypical emotions in Nikola’s face with varying degrees of accuracy. RIKEN said it was because Nikola’s silicone skin was less elastic than real human skin and couldn’t form wrinkles very well. This makes emotions like disgust harder to identify because the unit of action for nose wrinkles could not be included.

“In the short term, androids like Nikola can be important research tools for social psychology or even social neuroscience,” Sato said. “Compared to human confederates, androids are good at controlling behaviors and can facilitate rigorous empirical investigation of human social interactions.”

The ultimate goal of Guardian robot project is to build an android that can help people, especially those with physical needs who might live on their own. “Androids capable of emotionally communicating with us will be useful in a wide range of real-life situations, such as elderly care, and can promote human well-being,” Sato said.

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