From Neurophilosophy:
If a rapid series of taps are applied first to your wrist and then to your elbow, you will experience a perceptual illusion, in which phantom sensations are felt along the skin connecting the two points that were actually touched. This feels as if a tiny rabbit is hopping along your skin from the wrist to the elbow, and is therefore referred to as the “cutaneous rabbit”. The illusion indicates that our perceptions of sensory inputs do not enter conscious awareness until after the integration of events occuring within a certain time window, and that the sensory events taking place at a certain point can be influenced by future events.
A group of Japanese researchers now shows that this illusion is not just confined to the body. In a new study published today in the Journal of Neuroscience, they report that the cutaneous rabbit can easily be induced to “hop out” of the body, so that the illusory sensations are perceived to originate not from the body itself, but from external objects that interact with it.
More here.
