cutaneous rabbit illusion

IEEE did an article on a new technology from phillips: a jacket with 64 little actuators in it that let you feel a movie or tv show. for instance, in a frightening scene it can make you feel like a shiver is running up your spine. the question came up about how only having 4 actuators for the entire length of your arm is enough, and the article references the 'cutaneous rabbit illusion' as the answer. my interest was piqued so i went to good ole wikipedia. it turns out that if your wrist is tapped several times rapidly and then your inner elbow is tapped several times, your brain tricks you into thinking you are being tapped at every point along your forearm - like a rabbit running up your arm. using this, four actuators can create the illsuion of being touched along the entire arm. neat.