The Memory Density Perception

As an adult, you write down very little memory because your brain has figured out a pretty good model of the world. But if something really novel happens, that's when your brain writes something down and says, Whoa, wait a minute, I'm surprised. So it is true that things that are novel generally seem to last longer. However, it should be noted that when things are actually life threatening, you have essentially an emergency response memory system that kicks into gear. And this is underpinned by a part of the brain called the amygdala. The point of memory is to make sure that you write down stuff that is important and specifically life threateningly important.