From Nature:
A brain implant can decode a person’s internal chatter — but the device works only if the user thinks of a preset password1.
The mind-reading device, or brain–computer interface (BCI), accurately deciphered up to 74% of imagined sentences. The system began decoding users’ internal speech — the silent dialogue in people’s minds — only when they thought of a specific keyword. This ensured that the system did not accidentally translate sentences that users would rather keep to themselves. The study, published in Cell on 14 August, represents a “technically impressive and meaningful step” towards developing BCI devices that accurately decode internal speech, says Sarah Wandelt, a neural engineer at the Feinstein Institutes for Medical Research in Manhasset, New York, who was not involved in the work. The password mechanism also offers a straightforward way to protect users’ privacy, a crucial feature for real-world use, adds Wandelt.