By scanning the brains of adults who played Pokémon as kids, researchers learned that this group of people have a brain region that responds more to the cartoon characters than to other pictures. More importantly, this charming research method has given us new insight into how the brain organizes visual information.

For the study, published today in the journal Nature Human Behavior, researchers recruited 11 adults who were “experienced” Pokémon players — meaning they began playing between the ages of five and eight, continued for a while, and then played again as adults — and 11 novices. First, they tested all of the participants on the names of pokémon to make sure the pros actually could tell a Clefairy from a Chansey. Next, they scanned the participants’ brains while showing them images of all 150 original pokémon (in rounds of eight) alongside other images, like animals, faces, cars, words, corridors, and other cartoons. In experienced players, a specific region responded more to the pokémon than to these other images. For novices, this region — which is called the occipitotemporal sulcus and often processes animal images — didn’t show a preference for pokémon.

It’s not that surprising that playing many hours of Pokémon as a kid would lead to brain changes; looking at almost anything for long enough will do the same thing. We already know that the brain has cell clusters that respond to certain images, and there’s even one for recognizing Jennifer Aniston. The bigger mystery is how the brain learns to recognize different images. What predicts which part of the brain will respond? Does the brain categorize images (and therefore develop these regions) based on how animated or still they are? Is it based on how round or linear an object is?

The usual way to investigate this is to teach children (whose brains are still developing) to recognize a new visual stimulus and then see which brain region reacts. Study co-author Jesse Gomez, a postdoctoral fellow in psychology at the University of California at Berkeley, was inspired by this type of research on monkeys. But “it seems a little bit unethical to have a kid come in and trap them for eight hours a day and have them learn a new visual stimulus,” Gomez says. Teaching a new visual stimulus is a carefully controlled process. To make sure that you get clean data, you need to show all subjects the same picture with the same brightness and viewed from the same distance, and you need to show it over and over again.

The project seemed like a pipe dream until Gomez realized that pokémon, specifically the kind from the Game Boy games from the 1990s, would be perfect for this task. “I spent almost as much time playing that game as I did reading and stuff, at least for a couple of years when I was six and seven,” he says. For this generation, everyone saw the same images (black-and-white pokémon that didn’t move), and most people held the Game Boy about a foot away from their face, making this an ideal experiment.

The results support a theory called “eccentricity bias,” which suggests that the size of the images we’re looking at and whether we’re looking at it with central or peripheral vision will predict which area of the brain will respond. This particular region is associated with people looking directly at an image. Since nobody spent hours as a kid playing Pokémon on their Game Boy using just their peripheral vision, the theory checked out.

This isn’t the first time Gomez has studied the brain using pokémon. He’s also done scans of kids looking at pokémon, and he says that similar methods could be used when it comes to sound. When pokémon appear, they make a certain sound, and Gomez thinks it might be interesting to see whether there’s a “pokémon region” in the auditory part of the brain, too.