In China, the government is mining data from some employees’ brains by having them wear caps that scan their brainwaves for anxiety, rage, or fatigue. Lest you think other countries are above this kind of mind-reading, police worldwide have been exploring “brain-fingerprinting” technology, which analyzes automatic responses that occur in our brains when we encounter stimuli we recognize. The claim is that this could enable police to interrogate a suspect’s brain; his brain responses would be more negative for faces or phrases he doesn’t recognize than for faces or phrases he does recognize. The tech is scientifically questionable, yet India’s...