Have you ever walked into a hotel room, tossed your key card somewhere, and a few seconds later forgotten where you put it? The data just vanishes from the brain's hard drive. Why? Because our brains are simultaneously processing all kinds of information—what city or time zone am I in, how long until my appointment, when is it time to eat? With a limited capacity of our short-term memory, the location of the room card just doesn't make the cut.