The doorway effect suggests that there's more to the remembering than just what you paid attention to, when it happened, and how hard you tried. Instead, some forms of memory seem to be optimized to keep information ready-to-hand until its shelf life expires, and then purge that information in favor of new stuff. Radvansky and colleagues call this sort of memory representation an “event model,” and propose that walking through a doorway is a good time to purge your event models because whatever happened in the old room is likely to become less relevant now that you have changed venues. That thing in the box? Oh, that's from what I was doing before I got here; we can forget all about that. Other changes may induce a purge as well: A friend knocks on the door, you finish the task you were working on, or your computer battery runs down and you have to plug in to recharge.
Why would we have a memory system set up to forget things as soon as we finish one thing and move on to another? Because we can’t keep everything ready-to-hand, and most of the time the system functions beautifully. It’s the failures of the system—and data from the lab—that give us a completely new idea of how the system works.
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