Ghost Illusion Created with New Robot

"Sometimes, people report having felt a strange, unseen presence around them and may attribute it to a ghost. Now in a new study, scientist describe how the "ghost" is an illusion made by the brain.

The robot was made in two parts, one part was in front of the participant and the other part behind. The participants were given blindfolds and earphones for the experiment. The participants reached out in front of themselves and tapped a button on the robot, triggering the robot behind them to reproduce the participants arm movement, and touch their backs. This created the illusion that the participants were reaching out in front of them and touching their own backs."

http://m.livescience.com/48649-ghost-illusion-created-with-new-robot.html