Ever get that tingly creeping feeling that someone is behind you, only to turn around and discover there's nothing there? That's called "Feeling of Presence," and it doesn't mean you're getting trailed by a ghoul. It can be a symptom of many neurological conditions, which is why scientists custom-built a robot to induce that very feeling by following people around and tapping them.
The appropriately-named "Phantom Omni" induces hallucinatory sensations that can make people feel like they're in a crowded room when they're really alone, or that they're moving backwards when they're actually standing still. It works by manipulating sensorimotor signals to create "the strange sensation that somebody is nearby when no one is actually present and cannot be seen," according to a paper published by the researchers.
Now, you're probably wondering why anyone would create a robot that basically exists to give people a bad case of heebie-jeebies. They're hoping they can use this research to help people with neurological and psychiatric issues, since putting people in sessions with this type of robot might help them learn to regulate their responses to similar symptoms that arise from their conditions. The thinking is that if a person learns how to downplay their reaction to a hallucinatory feeling with the robot, they'll be able to do it when it hits them out in the world. [Washington Post - Scientific American]