When is a lab rat not a lab rat? When it's a robot that looks like a lab rat and is designed to make the other rats depressed for research purposes, of course.
Anyway, this is the scenario at Waseda University's Taknishi Lab in Japan, where a team led by Hiroyuki Ishii has created a robotic rat to make the lives of real rats miserable. The researchers aren't simply being cruel. They are stressing out the rats to study their chemistry when external stimuli induce fear and pain. This process previously involved things like forcing rats to swim and artificially altering their genetic makeup, so perhaps the robotic method isn't such a bad idea.
Rats are often used to stand in for humans in the lab, and studying depression in rats can lead to methods for treating depression in humans. The scientists published an account of their work on the Waseda Rat 3 (WR-3) in the journal Advanced Robotics (registration required).
Scientists at Waseda University's Taknishi Lab in Japan created the Waseda Rat-3 robot as part of their research into depression. The robot was used to harass real lab rats to induce depression.
(Source: Waseda University)
The Waseda researchers have been exploring robot-rat interaction for some time, having already created the WR-1, WR-2, and WR-4 to perform various lab functions, according to the lab's website.
In their paper, the researchers said they designed the WR-3 to "interact with a rat in the manner of interactions between rats." The robot is the size of a mature rat and has 14 active degrees of freedom, most of which are used to imitate typical rat motions, such as rearing or grooming. Servo motors drive leg actuation, while shape memory alloy wires control the pitch and yaw in the WR-3's neck. A servo motor drives a waist joint, and the robot has two active locomotion wheels in its hips.
Scientists also programmed the WR-3 with three different behavior algorithms (chasing, continuous attack, and interactive attack), giving the robot three ways to terrorize rats. Two test blocks of 12 immature rats each were used to test the WR-3. The researchers said they believed chasing caused more fear than pain, so they focused their attention on the more stressful continuous attack and interactive attack modes.
In the continuous attack mode, the WR-3 attacked the lab rats for five days straight. In the interactive attack mode, the rats were attacked upon movement. The idea was to see if the rats who suffered depression as a result of the harassment would be less mobile. The rats were then given a rest period and subjected to further testing, which found that rats that had been previously harassed were more traumatized by further harassment.
The researchers said they eventually want to test a similar method on humans. I think it might be challenging to find people who don't mind having a robot chase them around for several days.