Rabbit Chase

A New Wearable Gadget uses Sensory Illusion
What makes the amBX jacket (pictured left) so exciting? At first glance, the gaming accessory appears to be a nice, lightweight instrument of ubiquitous computing (we won't go too far into the faults or merits of Star Trek-inspired aesthetic here).

Its array of actuators produce physical sensations in the wearer that correspond with specific emotions. As one of the researchers explains, "We want people to feel Bruce Lee's anxiety." (we also won't go too far into the faults or merits of forced empathy.)

What is REALLY interesting, though, is a trick that the jacket designers have used to reduce the number of actuators involved - a trick called the Cutaneous Rabbit Illusion.

The designers were trying to figure out how to simulate a sensation such as a "tingle running up the spine". How could a group of vibrating motors create the illusion of a continuous sensation? The problem was one of resolution, so it could be avoided by embedding a very high density of actuating points, but would then result in a bulky garment requiring lots of power.

They did their haptics homework, and came across a peculiar physiological phenomenon that would solve the problem. In 1972, researchers at Princeton University found that by tapping someone's elbow and wrist, their mind produces the feeling that the taps are running between those two points.

The taps feel like tiny bunnies hopping up along the arm, hence the Rabbit Illusion. amBX researchers found that they could space actuators 15cm apart in the sleeve, and produce the sensory illusion of a continuous series of actuators along it. In the end, the jacket is quite thin, hosting merely 64 sensors around the torso, and able to run on AA batteries.

Sometimes, finding what is truly innovative about a new product can be a challenge. When that product is marketed as "wearable electronics", uniqueness is easily confused with its general novelty. For the amBX jacket, true innovation lies in the cross-disciplinary research that uncovered a strange fact about the human body.

See the IEEE Spectrum article about the amBX jacket, Jacket Lets You Feel the Movies , the amBX website and scientific articles on the Cutaneous Rabbit Phenomenon.