Rats Learn To Play DOOM In This Automated VR Arena

Rat playing DOOM

When we run an article with “DOOM” in the title, it’s typically another example of getting the venerable game running on some minimalist platform. This DOOM-based VR rig for rats, though, is less about hacking DOOM, and more about hacking the rats.

What started as a side project for [Viktor Tóth] has evolved into quite a complex apparatus. At the center of the rig is an omnidirectional treadmill comprised of a polystyrene ball about the size of a bowling ball. The ball is free to rotate, with sensors detecting rotation in two axes — it’s basically a big electromechanical mouse upside down. The rat rides at the top of the ball, wearing a harness to keep it from slipping off. A large curved monitor sits right in front of the rat to display the virtual environment, which is a custom DOOM map.

With the VR rig built, [Viktor] worked on automating the training. A treat dispenser provides the proper motivation, while powered drive wheels engage with the ball to nudge the rat if it gets stuck in the virtual world. [Viktor] says he has trained three rats — [Romero], [Carmack], and [Tom] — to walk down a straight hallway using this automated method. As for the meat of the game — shooting monsters — [Viktor] has that covered too, with a sensor that detects when a rat rears up on its hind legs to register a shot.

Total training time to get the rats to the point seen in the video was about six weeks, and [Viktor] reports the whole thing cost him about $2000. That’s a lot of time and money, but the results are pretty interesting. If you’re more interested in minimalist DOOM builds, we understand — check out DOOM on a lightbulb, or a thermostat, or even a GPS.

[via IGN]

Thanks to [my son Tom] for the tip!

29 thoughts on “Rats Learn To Play DOOM In This Automated VR Arena

  1. I have four rats, so am very aware how intelligent they can be, especially if food is involved.
    Awesome setup and the experiment does not seem too stressful for the rat.

    However I am not sure, if the rat was trained to ‘run straight in Doom’ or simply ‘run on the treadmill’ to receive the reward. In the video, the rat does not seem to focus on the monitor but on the treat dispenser. This could be tested without the monitor, whether the behavior is still the same.
    Still an impressive setup that could be used for further training.

    1. I agree. I thought the same thing when watching. I think variables need to be eliminated. The treat tubes need to be stashed out of sight until the goal is reached. With the setup he has, an extra servo wouldn’t be too much work. Then put in some twists and turns. Maybe make the screen move around the ball to make those turns more natural for a rat. We don’t really need to get the rats to strafe just because they’re playing Doom. Then we’d really know if they’re navigating of just eating snacks while scurrying further into the dispenser when the snacks stop.

  2. Looking into this made me slightly nostalgic, as I’ve cared for a dozen rats when I was younger. I’ve studied the material but never got past teaching them small tricks, but always wondered if I could teach them to solve a Rubik’s cube, If only good enough to fake it. In the end, I decided the animals would be better off if I didn’t keep them as a pet.

    It’s clear there went a lot of time and thought into designing and building the mechanical and electrical systems. I like the design of how ball movement is detected and enlarged with motors. However, the experiment side is slightly lacking the knowledge of training small rodents. For example: Rats don’t see very well with their eyes, and heavily rely on their whiskers, sense of smell, and hearing. This might require a different setup over a large curved screen, where a couple of LEDs might be more suitable. But in general, just start easy and teach the pets a few tricks and then upgrade to a few wooden T-mazes before attempting to play Doom. Maybe you can incorporate hearing and transmit ultrasound from different directions or at different pitches.

    I can recommend the ratbehavior website and Shadows The Rat on YT. Both pages are very insightful, even if you don’t own a rodent yourself. Also have a look at DeepSqueak an AI to determine the mood of the rodents by listening to the ultrasound.

    1. i was thinking the same don’t rats have a huge blind spot in front of them? if so a flat screen is really not optimal.
      also i believe their color and contrast perception is different you might need to adapt the doom output to more suit our furry friends if you want better results.

    1. Judging from my rats: Pee on the ball whenever they want, they might be to stressed in the harness to actually poop. If not it will fall down whatever direction the ball is spinning next. Should not be an issue for short and supervised sessions.

    2. Absolutely yes. My company custom made a similar rodent VR system a few years ago for a neuroscience lab and it was always covered in rodent pee. I’m kinda glad they didn’t renew their support contract, so we don’t have to go touch it anymore (though they are still using the apparatus last I heard, which is good!)

  3. > it’s basically a big electromechanical mouse upside down.

    You mean a trackball?! Do HaD readers not know that word anymore? Or just [Dan Maloney]? ;-)

    If the intention was to make it easier for the younger touch-screen generations you may need to explain what a computer mouse is, too. :-)

  4. It would be neat if they had indeed trained a rat to play Doom, but nothing in the attached video suggests that the rat is in any way interacting with the screen at all. It’s just running on its trackball and getting its sugary reward.

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