Cockroaches can succumb to peer pressure, study finds
NEW YORK TIMES NEWS SERVICE
November 19, 2007
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.
Advertisement“We decided to join the two approaches,” said Jose Halloy, a biology researcher at the Free University of Brussels and lead author of a paper describing the research in Friday's issue of the journal Science.
Halloy and his colleagues worked with roaches because their societies are simple, egalitarian and democratic, with none of the social stratification that mark some other insect societies – no queen bees, no worker ants. “Cockroaches are not like that,” 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 6-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.
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, it was the robotic roaches who 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. The experiment would then test to see if newly hatched chicks would bond to the robot as if it were their mother.
The current research did not test whether the robots could lead the cockroaches to something they really disliked, like broad daylight or insecticide. Halloy said the results also apply only to cockroaches. “We are not interested in people,” he said.
»Next Story»
