This reminds me of the book Phantoms in the Brain by one http://en.wikipedia.org/wiki/Vilayanur_S._Ramachandran http://en.wikipedia.org/wiki/Vilayanur_S._Ramach

This reminds me of the book Phantoms in the Brain by one http://en.wikipedia.org/wiki/Vilayanur_S._Ramachandran http://en.wikipedia.org/wiki/Vilayanur_S._Ramachandran in which he describes a similar experiment. It's a great read by the way. Anyway, as I recall, watching someone tap and stroke a model body part, say a nose, in a non predictable pattern, whilst an unseen hand replicates the touches exactly on your own nose, can result in an overwhelming sensation that the model, though yards away from you, is actually your own nose. Always meant to try it out, it sounds great fun. I don't know if the Wired article or the experiment itself has glossed over this first stage - before the delay is introduced - but perhaps if the first step has already introduced the spooky feeling of your back being an arms length in front of you (maybe to a milder degree than if it had looked like a back), then when you start feeling your back (still in front of you) being touched when you can clearly see noone is touching it, this could naturally lead to a feeling of an invisible actor?