A robotic "sixth finger" that can be worn on the hand next to the pinky has been created by researchers studying how brains react to new and independent body parts.
Researchers at the University of Electro-Communications in Japan and French National Centre for Scientific Research co-developed the artificial appendage, first embarking on the project in 2016.
Electrical signals from muscles are first measured by four sensors attached to the forearm. The signals are then transferred to a motor to control the robotic finger.
"We know that we can move our own body with our brain, but when a new body part is formed, can the brain adapt? We thought this was an interesting question," Yoichi Miyawaki, a professor at the University of Electro-Communications told Reuters.
"We were interested in how the brain will accept it (the sixth finger) or change, rather than using it for convenience," he said.
Although their research is primarily focused on the brain's reaction to an extra body part, they say the sixth finger can enhance daily human activities such as typing on a computer keyboard or carrying more objects.
Miyawaki said if this technology develops further, the concept of normality may no longer exist.
"There may come an era where people can choose to have five (fingers) one day, and six (fingers) the next. Glasses are a good example. It has become an accessory, but it's got a function," he said.
"You think, what is normal and what is a handicap? Would you be handicapped if you are not normal?"