Doctors have used a brain-reading device to hold simple conversations with “locked-in” patients in work that promises to transform the lives of people who are too disabled to communicate. The groundbreaking technology allows the paralysed patients – who have not been able to speak for years – to answer “yes” or “no” to questions by detecting telltale patterns in their brain activity. Three women and one man, aged 24 to 76, were trained to use