While your fingers are in firmly in control of hand-held devices, they're guided strictly by your eyes -- and Microsoft thinks that's a waste of your sense of touch. Researcher Hong Tan found that using so-called haptics to add tactile sensations to screens can have some concrete benefits. For instance, by adding a keyboard-like "click" feeling to a Surface keyboard cover, one study showed that subjects could type faster and more accurately on it. Other potential uses include enhanced interfaces that let you feel resistance when you move a folder on the screen, or the ability to feel "textures" like rough cloth on a screen. Several methods can be used to create such feedback. One way is to put a material that bends when charged under a screen to simulate a click, while another uses electrostatic vibration to put a cushion of air under your finger, making a surface feel smooth or sticky.