The rat’s movements translated into rotations of the ball, which were then translated into movement inside the iconic first-person shooter. Half a decade later, Tóth’s setup has received a major upgrade, giving the daring demon-slaying rats an entirely newfound level of immersion. For one, this strictly isn’t an advanced brain computer interface (BCI) experiment that involves scanning the rat’s brain waves. “While advanced training wasn’t completed due to time constraints, initial data showed promising engagement with the system,” the website notes. However, the rats may need a break every once in a while, as the “impact of prolonged VR exposure on rat well-being needs further research.”More on the experiment: Scientist Who Trained Rats to Play “Doom II” Says He May Start Twitch Channel