The researchers, who published their results in the journal Science, showed that when they shortened one of the robot's legs, it responded by shifting its gait more effectively when using an internal model than when the robot had no internal model.

But some remain unconvinced that there is a genuine benefit to using internal models in this way. It is unlikely that cockroaches have internal models of themselves, says Inman Harvey, a roboticist at the University of Sussex, in Brighton, UK. "And yet if a cockroach's leg comes off, it manages to change from a six-legged gait to a five-legged one," he says. It may turn out that in engineering terms, there is an advantage, but that has yet to be shown, Harvey says.

According to Bongard, having a self model is the only way that he and his colleagues can internally rehearse new behaviors before actually trying them out in reality. In real situations, the robot itself is changing all the time. "The strength of the motors and the reliability of the sensors gently degrade over time, and the robot would need to discover and update this information on its own," Bongard says. And this couldn't be done reliably by a human operator because it would involve such subtle information and would have to be done continuously.

"Self modelling is important," says Igor Aleksander, a neural-systems engineer at Imperial College London, UK. In order to plan its actions, a robot does need to know where it is and what its limbs are up to. However, the danger, Aleksander says, is to read too much into this and start attributing some form of consciousness to the robot.

Bongard agrees and says that this sort of self-awareness should not be confused with consciousness. The ability to build up an understanding of one's own body seems sufficient to explain a lot of human behavior, without having to resort to the mysterious concept of consciousness, he says.