Published in Alex Holcombe's blog
Author Alex O. Holcombe

At first, I was underwhelmed by this one. But what it does is demonstrate the existence of stretch receptors in our system for the sensation of touch. Running an object (like a stick, or a pen) along the fine teeth of a comb, causes successive teeth of the comb to deflect laterally. There is no appreciable up-and-down component to the teeth’s movement, just the side-to-side movement.