Surgically implanted devices that allow paralyzed people to speak can also eavesdrop on their inner monologue.
That’s the conclusion of a study of brain-computer interfaces (BCIs) in the journal Cell.
The finding could lead to BCIs that allow paralyzed users to produce synthesized speech more quickly and with less effort.
But the idea that new technology can decode a person’s inner voice is “unsettling,” says Nita Farahany, a professor of law and philosophy at Duke University and author of the book: The Battle for Your Brain.
“The more we push this research forward, the more transparent our brains become,” Farahany says, adding that measures to protect people’s mental privacy are lagging behind technology that decodes signals in the brain.
From brain signal to speech
BCI’s are able to decode speech using tiny electrode arrays that monitor activity in the brain’s motor cortex, which controls the muscles involved in speaking. Until now, those devices have relied on signals produced when a paralyzed person is actively trying to speak a word or sentence.