With a tap on the back, researchers create ghostly sensation

Lab illusion probes supernatural experiences, hallucinations

volunteer wearing virtual reality headgear

GET BACK  A volunteer wears virtual reality headgear while hooked up to an apparatus that uses back taps to induce a feeling of an unseen person standing nearby.

Alain Herzog/EPFL

Using well-timed back taps supplied by an odd contraption, scientists have figured out how to induce the weird sensation that someone is standing nearby when not a soul is there.