Perfecting a robot that bridges the gap will call for advances in almost every facet of modern robotics: artificial intelligence, machine vision, mechanical and electrical design, signal processing.

But if CAPTCHAs are broken it might not be a bad thing, because it would signal a breakthrough in machine vision that would, for example, make automated book-scanners far more accurate.

It transmits a signal and the machine on the other end spits out a copy.