Brit: Does this sound familiar? You get up to grab your phone, or a cup of tea, or something else, in the other room, but once you’re there, you have absolutely no idea why.

Were you distracted? Sure, maybe. But it could also be because you walked through a doorway. Yup.

According to psychologists at the University of Notre Dame, something as simple as walking through a doorway can make you forget things! They found this out by testing undergrads in the lab. They asked students to place six blocks of various shapes and colors in a shoebox, cover it with a lid, and then carry the box across one big room, or into another room.

There, the students were quizzed about the contents of their boxes. Had they carried a yellow sphere? What about a green cube?

Now, most people could remember the objects most of the time, but when participants had walked through doorways, their performance was consistently worse. Something about doorways seemed to make them forget. This happens not only with real doors, but in virtual environments, too, and even when people are asked simply to imagine crossing a threshold.

It’s called the location updating effect, or more simply, the doorway effect. You might think this is just a case of context. Like, if you walk back into the original room, maybe that can help you remember. But the Notre Dame scientists tested this, and that didn’t make participants any less forgetful.

The forgetting wasn’t just about being in a different room. The act of walking through the doorway was the culprit. So what’s going on?

The best explanation has to do with how our brains process events. After all, you can only think about so many things at once. Working memory, our neural representation of what’s currently happening, is limited. So the best way for our brains to deal with everything is to break it into chunks.

According to this theory—known as the Event Segmentation Theory—our brains create representations of events called event models, which let us predict what might come next at any given moment.

Like, if you see someone tie one shoe, it’s a pretty safe bet that the next thing they’re going to do is tie the other one. But these event models need to be updated, as the circumstances around you change. Once someone’s done tying their shoes, for example, having that model in your head isn’t very useful.

That’s where doorways—and other so-called event boundaries—come in. Doorways are a sign that something’s changed, and maybe you need to refresh. The problem is that when your brain updates this status report, that old information isn’t as accessible—even if you still need it.

Psychologists also think people might have a hard time remembering things—like those colored blocks in the experiments—because they create two event models with those objects, one for each room. So, when it comes time to retrieve the information about what’s in the box, or what you went into the other room to find, the two models compete and interfere with each other. But this whole system that your brain has for processing things still is useful—even if it sometimes leaves you in the kitchen, wondering why you’re there.

That’s because, more often than not, passing through a door does mean that a new event is beginning, which means that it’s okay to dump all the information about the old event. So this kind of forgetting might be annoying, but isn’t really a bad thing. And it’s not a sign that you’re getting old or developing dementia.

Scientists actually checked this, and the doorway effect was just as strong in college students as it was in a group of older people. In fact, event boundaries like doorways sometimes might even help you remember. In a different experiment, the same Notre Dame psychologists challenged students to remember a list of words that was read aloud, half in one spot, and the other half in another room, or the same distance away within the same room.

The test subjects remembered more of the words when they crossed through a doorway than when they just moved to another part of the room. Here, the doorway was beneficial: by divvying up the words in two separate event models, the brain can structure the information better, and take more of it in.

So, if you end up in your kitchen baffled by why you’re there, don’t worry. Your brain made a tiny mistake. In the grand scheme of things, it’s doing things just right.

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