Poor arachnophobes -- it's bad enough that 3D movies can make it look like swarms of eight-legged freaks are pouring out of the screen, now Disney wants you to feel the creepy crawlies, too. In a presumed effort to one-up those "4D" chairs used at Shrek's castle down in Orlando, the company has been working on what it calls Tactile Brush -- a chair with an array of 12 vibrating coils that are able to simulate anything from the sensation of speeding around a race track to the delicate drip of rain on your back. Two techniques are used: apparent motion, which triggers two motors in quick succession to create the illusion of something moving over your skin, and phantom sensation, in which two stationary vibrations are felt as a single tingle between the two points. Disney researchers demoed Tactile Brush at the Conference on Human Factors in Computing Systems in Vancouver using a racing game, but hope to bring it to amusement park rides and movie theaters -...