RIKEN Develops Expressive Android ― Has 17 Facial Muscles and Movement Similar to a Human

A joint research team led by Wataru Sato, leader of RIKEN's Psychological Process Research Team, and Takashi Minato, leader of the Guardian Robot Project's Interactive Robot Research Team, part of the RIKEN Information R&D and Strategy Headquarters, has developed an android that can make human-like facial expressions and has demonstrated its validity in psychological experiments. This is the first example of a robot that can elaborately reproduce the movements of human facial muscles and which has had its emotive validity rigorously verified in psychological experiments. The results were published in Frontiers in Psychology.

The joint research team developed an android head using human anatomical and psychological expertise, naming it Nikola. The validity of Nikola's facial expressions were then tested in three psychological experiments.

In the first experiment, Nikola produced 17 facial muscle movements, such as raising an eyebrow or the corner of its mouth. These movements were confirmed using a method for evaluating human facial muscle activity called facial action coding, which facial expression specialists use in psychological research. The results proved that all facial muscles had the same movement patterns as humans.

Next, Nikola was tested by 30 participants from the general public to see if they could recognize the emotions in photographs of the robot expressing six basic emotions (anger, disgust, fear, happiness, sadness, and surprise). The results showed that all emotions were appropriately recognized at statistically significant levels.

Third, a video was produced of Nikola showing the six basic emotional expressions at four different speeds (0.3 seconds, 0.5 seconds, 1 second, and 2 seconds), with the 30 participants evaluating the naturalness of each expression. Results showed that the effects of speed vary according to emotion, just as it does in human facial expressions. For example, faster expressions of surprise are seen as more natural, but slower expressions are more natural for sadness.

The findings are the first to demonstrate that androids can express emotions in spatial and temporal patterns similar to those of humans.

Nikola is expected to see use in future social psychology experiments examining emotional communication. In the past, such experiments could not be controlled because confederates (participants with pre-rehearsed behaviors) were relied on to make facial expressions, and methods that involved showing participants photographs of facial expressions had a low sense of reality. It is hoped that Nikola will allow for emotional communication to be examined using a controlled form of reality.

It has also been shown that warm communication can reduce stress and problematic behaviors in nursing care. The staffing shortage in this field means that if androids that can communicate emotionally, like Nikola, can be developed in the future, they will contribute to solving problems in society.