Using a Robotic Third Thumb can impact how the hand is represented in the brain, finds a new study led by UCL researchers.
People equipped with an additional, robotic thumb learned to control it with their toes – but prolonged used may come at a cost of their brains being less certain about how their hands work.
Danielle Clode at University College London and her colleagues gave 36 people a prosthetic thumb that wrapped around their wrist and sat underneath their little finger. All were right-handed, and wore the device on their dominant hand.
The third thumb’s movement was controlled by sensors attached to the user’s big toes, and communications were sent using wireless technology affixed at the wrist and ankle. By wiggling each toe, the augmented humans could move the thumb in different directions and clench its grip.
Paulina Kieliba said: “Our study is the first one investigating the use of an augmentation device outside of a lab. It is the first augmentation study carried over multiple days of prolonged training, and the first to have an untrained comparison group. The success of our study shows the value of neuroscientists working closely together with designers and engineers, to ensure that augmentation devices make the most of our brains’ ability to learn and adapt, while also ensuring that augmentation devices can be used safely.”
For five days, participants were encouraged to use the robotic Third Thumb can impact how the hand is represented in the brain, finds a new study led by UCL researchers. both in laboratory settings and in the wider world. “One of the goals of the training was to push the participants about what was possible and train them in unique new ways of handling objects,” says Clode.
The additional thumb could cradle a cup of coffee while the same hand’s forefingers held a spoon to stir in milk, for instance, while some participants used the thumb to flick through pages of a book they were holding in the same hand. The average user wore the thumb for just under 3 hours a day.
“Technology is advancing, but no one is talking about whether our brain can deal with that,” says team member Paulina Kieliba, also at UCL.
“In our augmented population, on the right hand, the representation of individual fingers collapsed on each other,” says Kieliba – meaning the brain perceived each finger as more similar to each other than it did before the experiment. A week later, 12 of the participants returned for a third brain scan, where the effect of the brain changes had begun to wear off.
Designer Dani Clode (UCL Institute of Cognitive Neuroscience and Dani Clode Design), who was part of the core research team, said: “Our study shows that people can quickly learn to control an augmentation device and use it for their benefit, without overthinking. We saw that while using the Third Thumb, people changed their natural hand movements, and they also reported that the robotic thumb felt like part of their own body.”