The haptic interface is a new device that allows operators to interact with computer simulations in three dimensions. When they slip a finger into a sleeve, they can move a small ball on the screen inward and outward as well as up and down and back and forth. If they encounter a virtual object on the screen, like the crank in the video, they can "feel" it because the interface resists further movement much as it had encountered a physical object. Operators also can turn the crank or slow it down by exerting force on appropriate surfaces. Another demonstration of a haptic interface is the rocket ship ride at the end of the article.