Since Fujitsu's prototype Haptic Sensor Tablet revealed yesterday is all about touch, describing it will be like trying to explain how a steak tastes. But here goes: It works by emitting ultrasonic vibrations below the touchscreen, which can be pulsed with varying force on any region of the screen. Those oscillations actually push your finger off the surface of the tablet and, depending on the strength, can give different tactile sensations. For instance, a high-pressure layer of air can reduce friction, making the surface of the screen seem slippery. By contrast, rapidly varying the pulses can make the display seem rough or even bumpy.

At least, that's the theory. After trying it, we found some illusions like the slippery surface to be very convincing. Different textures could also exist on different regions of the screen at a resolution of several pixels. That made other simulations, like the clicking of a combination lock or DJ app volume control uncannily accurate. But the rough-texture test felt more like the screen was just sticky, and the bumpy experience was even less convincing. When touching the crocodile skin, for instance, it just felt like I was moving my finger over slippery and then clingy patches. When using it, there's also an unnatural, mildly disconcerting buzzing sensation. All said, though, it was still a lot of fun, and it's hard to see how you could get much more realistic than that with a smooth, 2D surface (as opposed to the popup overlay on the Tactus display, for instance). There's a video after the fold showing it in action, but we apologize for the occasionally poor sound quality -- as you'll see, each time the haptics activated, it messed up our camera's microphone.

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Fujitsu Haptic Sensory Tablet hands-on