Scientists have found a way to trick the body's senses into thinking a flat surface is actually sharp or pointed. Their findings will be presented next month at the IEEE International Symposium on Robot and Human Interactive Communication in Hatfield, England.

This new touch interface appears to show that it's possible to fool our sense of touch into feeling very fine and detailed sensations of pressure without pushing down against the skin. A virtual knife edge could bring an added sense of realism to touch-based haptic systems, such as those used in surgical simulators.

The goal of this field of touch technology, which is often called haptics, is to be able to simulate any shape, texture, or sensation, says Gabriel Robles-De-La-Torre, a neuroscientist and computer engineer based in Mexico City, who founded the International Society for Haptics and led the research. It's an important step toward developing haptic "displays," he says.

Sile O'Modhrain, an expert in haptics formerly at Queen's University of Belfast, Northern Ireland, agrees. She says the work should make haptics feel more realistic. "It's a way of improving the perceptual quality of the rendering of surfaces."

Although theoretically it may be possible to design a machine that could change its actual texture and shape to simulate a wide range of shapes and textures, such a mechanism would be unfeasibly complex and large. Instead, researchers like Robles-De-La-Torre have been exploring ways to exploit our sensory system's ability to be deceived.

"It's just a way of taking advantage of human perception," says Vincent Hayward, an electrical and computer engineer who works on haptics at McGill University in Montreal. It is somewhat similar to the illusion we experience when our eyes perceive a wide range of colors on a video display, even though the image consists of just three different colored pixels, he says.