" " Why do we often forget our reason for coming into a room once we go through the doorway? erhui1979/Getty Images

"There are things you know about, and things you don't, the known and the unknown, and in between are the doors." Keyboardist Ray Manzarek was explaining to a reporter how his band The Doors got its name. But that in between space can apply to more than just a rock group name.

We've all had the experience of getting up to do something, only to arrive in another room scratching our heads as to why we ever got up from the couch to begin with. It's such a common conundrum that University of Notre Dame Psychology professor Gabriel Radvansky and his colleagues set out to research it. Their findings were published in 2011 in the Quarterly Journal of Experimental Psychology.



The researchers learned that walking through doorways is a mental "event boundary" of sorts, one that divides our experiences in a subconscious way. So, when you're sitting at your kitchen table and you decide to retrieve your coffee mug from the living room, the act of passing through a doorway causes compartmentalization of the tasks in your mind — and you forget the very reason that caused you to set out on your short-circuited mission in the first place.

The Notre Dame team used both live and computer-based experiments to test these concepts. In the virtual environment, test subjects picked up shapes on a table, carried them to another room, and then swapped them for a different object. They repeated this process in a similarly sized environment where there was no doorway.

When the scientists compared results from the two scenarios, they saw that subjects tended to forget things much more frequently in the environment that featured — you guessed it — doors.

Then, they set up a similar test in a real-world setting. Subjects picked up an object, concealed it in a box, and then either walked across a room or through a doorway to another room. (Both distances were the same.) Again, the doorways seemed to increase forgetfulness.

Wait, what were we talking about? Oh yes, the doors.

The studies seem to indicate that our brains use certain boundaries as markers of sorts, and doorways cause us to process one task and file it away as "done." Most of the time this is a good thing since we can't possibly remember everything at one time. But it does present a problem if we haven't found our car keys just yet and are looking around for them.