I keep bumping-into this article from 2014 in various places, so I’ll go ahead and share a link in case anyone else has an interest in this sort of thing. My favorite line is “[a]rtificial ‘spectres’ were conjured up by an experiment which proved so disconcerting for participants that two begged for it to stop.”
About the images below: “To manifest their ghosts, the scientists set up a robot device that allowed volunteers to control the movements of a jointed mechanical arm with their index fingers.The movements were relayed to another robot arm behind them which touched their backs.When both the finger-pushing and back-touching occurred at the same time, it created the illusion that the volunteers were caressing their own backs.That felt weird enough to the blindfolded participants. But something a lot stranger happened when the back-touching was delayed and about 500 milliseconds out of sync with the finger movements.Suddenly the volunteers felt as if they were being watched, and touched, by one or more ghostly presences.At the same time, they had the disconcerting sensation of drifting backwards, towards the unseen hand.When questioned, several reported a strong feeling of invisible people being close to them. On average, they counted two, with up to four being reported…”
camcdaniel.com 