Friday, November 16, 2007

Led by Robots, Roaches Abandon Instincts

"Many a mother has said, with a sigh, “If your friends jumped off a cliff, would you jump, too?”

The answer, for cockroaches at least, may well be yes. Researchers using robotic roaches were able to persuade real cockroaches to do things that their instincts told them were not the best idea.

This experiment in bug peer pressure combined entomology, robotics and the study of ways that complex and even intelligent patterns can arise from simple behavior. Animal behavior research shows that swarms working together can prosper where individuals might fail, and robotics researchers have been experimenting with simple robots that, together, act a little like a swarm.

“We decided to join the two approaches,” said José Halloy, a biology researcher at the Free University of Brussels and lead author of a paper describing the research in today’s issue of the journal Science.

Dr. Halloy and his colleagues worked with roaches because their societies are simple, egalitarian and democratic, with none of the social stratification seen in some other insect societies — no queen bees, no worker ants. “Cockroaches are not like that,” Dr. Halloy said. “They live all together.”

They also have weak eyes, which allowed the researchers to create a robotic roach that resembles a miniature golf cart more than an insect. In the roach world, however, looking right is not as important as smelling right, and the scientists doused the machines with eau de cockroach sex hormones.

They set up a cockroach arena one yard in diameter. Two six-inch-wide plastic discs were suspended over it, providing the dark shelters that cockroaches prefer to congregate in. But one disc was darker and a more likely cockroach hangout.

When 16 cockroaches were placed in the arena, they naturally gravitated toward the darker disc, following what the researchers believe is an internal calculation of the amount of light and the number of other roaches, finding comfort in company.

Dr. Halloy then replaced four of the cockroaches with four robots equipped with sensors to measure light and the proximity of other robots. When the robots emulated the real roaches, the group continued to seek the dark and crowded place.

When the four robotic roaches were reprogrammed to prefer the lighter disc, however, the real roaches followed them about 60 percent of the time, in essence deferring their own judgment as the preference grew more popular. (The other 40 percent of the time, the robotic roaches succumbed to peer pressure and headed for the darkest place.)

“It’s a cascade of imitation, so a small effect can become quite large,” said Stephen Pratt, a professor of life sciences at Arizona State University. “This one is a real step forward. They’ve developed these theories about what kinds of individual behavior rules would have to follow to generate a collective intelligence. I thought it was very gratifying they could get the roaches to do what they normally would not do.”

The scientists plan to extend their research to higher animals. The next creation: a robotic chicken, which will look a little like a ball on tank treads with loudspeakers. Newly hatched chicks, which bond to the first thing they see, will do so with the robot as if it were their mother. The researchers say they hope to explore the chicks’ behavior with the false mother as leader.

The current research did not test whether the robots could lead the cockroaches to something they really disliked, like broad daylight or insecticide. The results also apply only to cockroaches, Dr. Halloy said. “We are not interested in people,” he said."

My question is...why did the programmed roaches follow the real roaches 40 percent of the time????

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