They look like Tupperware containers with a tangle of circuitry inside them, but prepare to be amazed. These are autonomous Neuro-Evolving Robotic Devices (NERDs)—nobody is controlling them with a remote. They are programmed to swim and to move toward a light source, but that’s it. When they are released simultaneously in a tank of water, each NERD swims to the light, where they cluster and bump into each other chaotically. But within a minute or two, they are somehow all swimming in the same direction, circling the light. In trial after trial, the NERDs exhibit this coordinated behavior.
“We stumbled upon this sort of serendipitously,” says Josh de Leeuw ’08, now in a doctoral program in cognitive science at Indiana University but previously a post-baccalaureate fellow in Professor of Biology John Long’s lab at Vassar. “We built these robots for a different experiment—one that didn’t work out so well. But one of the things we observed was patterns of behavior that were more coordinated than we thought they should be, given what the robots were programmed to do. So, we decided to investigate that further.”
de Leeuw, Long, and psychology professor Ken Livingston, who also collaborated on the project, were looking for answers to the basic question, What’s the mechanism that causes fish to school, or birds to flock, or insects to swarm? “There’s been lots of work on this—biologists observing real organisms and also people creating computer models that exhibit this kind of coordinated behavior,” de Leeuw says. “One of the assumptions that most of these models operate under is that there is a social mechanism at work here, that if you’re an individual agent in a group, you have to be able to detect other agents in the group. We wanted to challenge that and see what would happen if you couldn’t detect your neighbors.”
They built 10 NERDs programmed to swim on the surface of the water in a tank and to track a light source, but they were blind to each other. “We used a light source as a metaphor for food, some sort of goal that the robot is trying to achieve. So, each robot in the tank is trying to get closer to the light source. And what we find, not surprisingly, is that they all cluster around the light source. And some are traveling clockwise, and some are traveling counter-clockwise, and they’re bumping into each other. But after just a few minutes, their behavior becomes remarkably coordinated and they all end up traveling in the same direction.”
“What’s really cool about this is that what appears to be a very social act—this coordinated behavior that we see in biological agents—may be explainable at least in part by what we’re calling asocial mechanisms.” Long and de Leeuw are not arguing that coordinated behavior in biological agents doesn’t rely on social mechanisms—there is ample evidence that it does—but they are suggesting that the asocial mechanism may play a role in producing the social behavior.
Long and de Leeuw hope to have the results published in the near future. And then they’d like to investigate this more systematically. “We happened to choose this one particular system because we had already built these robots for another purpose, and this was the size tank we had available. So, we made a lot of choices, and they just happened to work. Now, we want to try to produce this behavior in a lot of different contexts and see when we get coordination and when we don’t.” They plan to build a computer simulation that will enable them to test lots of different variations and then take what they learn from those simulations and reproduce it in a robotic system.
de Leeuw presented their findings at the 2013 Annual Meeting for the Society for Integrative and Comparative Biology. “I had the video up on the screen, and I prefaced it by saying roughly what was going to happen. And then I watched people’s faces as they were watching the video, and it was really cool to see that ‘wow’ moment when the robots suddenly coordinated. People’s eyes widened a bit.”
--Julia Van Develder
NERDs photos courtesy of Josh de Leeuw; portrait ©Vassar College-John Rizzo