Do you ever find yourself entering a room to do something, and then almost instantly, you can’t remember what you were there for?

It happens to me usually at least once a day, sometimes more. I often think that I’m either prematurely going senile, I’m on my 11th consecutive year of pregnancy brain or I’ve just plain old lost the plot.

I even walk into rooms that have a specific purpose like the laundry and can’t remember why I’m there. Usually, it’s to check to see if the machine has finished its cycle or whatnot, but I can stand there baffled for a few minutes before I remember what I’m doing. Same with things like opening the fridge door and forgetting why, or wandering around looking for my keys before I forget what I was looking for.

It seems that there’s a scientific explanation for this, which makes me feel a teensy bit better about my brain. In fact, it might be that the doorway you walked through is to blame.

Scientists have dubbed it “the doorway effect”. Walking through a door way from one room to another can empty your mind and cause you to forget.

It’s not that doorways have magical powers that can cause temporary amnesia in those who walk through them, of course. It does have to do with our brains and the way we handle short-term memory.

Researchers studying memory found that participants experienced a divide in their memory, quite literally, when they walked through a door. Crossing from one side of a doorway to another causes us to put a literal mental block in our brains and we dump about 25% of our short-term memory.

As we go about our daily business, our attention shifts between different “levels” such as goals and ambitions, plans and strategies, and the lowest “levels” where our solid actions take place. If things are going well, when we are in familiar situations, our attention stays where we need it to be and everything goes swimmingly. This is how we do things like drive places, seemingly on autopilot, changing gears, indicating, and doing all of those things while maybe we’ve also been deep in thought at the same time.

“The doorway effect” happens when our attention moves between these “levels” and relies on our memories to help us in the new environment we have walked in to.

We have episodic memories, generally. If you think back on things, you’ll notice that memories don’t always function as a clear narrative – a story from start to finish – but they’re usually split up into segments. Therefore, when we walk through a door, our brains see that we’re in a new place and adjust accordingly.

So, you were in the bedroom, and you thought you’d go put the kettle on in the kitchen, but when you got there, you couldn’t remember what you were there for. So you unstack the dishwasher, then walk back to the bedroom where you remember you were going to get yourself a cuppa.

Entering the new environment caused your brain to erase the old model of thinking (being in your bedroom) to make way for a new environment (being in the kitchen). The hastily thought up plan is quickly forgotten when the context changes.

Other scientists have named this experience, the “location-updating effect.” A bit like when your GPS or Siri has to update itself after you ignore its recommendations, your brain has to as well.

It’s not just doorways that this happens in, it can be anywhere where we have to switch quickly between one thing and another.

This explains why you sit down to pay bills in internet banking, but you get distracted by something more interesting in another browser tab, and then you click on another link, and another, end up watching Youtube for a bit, and two hours later, you remember you were supposed to be paying bills. Don’t pretend I’m the only one this happens to.

So next time it happens, don’t beat yourself up about it, it’s just your brain doing what it’s supposed to. Phew.