We recently posted a litigation guide on our website. On of the topics we cover is how you can help your case, be it an insurance claim or a lawsuit, by preserving evidence. By that, we mean that the accident scene as it exists at the time of the accident won't last in its condition for very long. To show the insurance company or a jury exactly what happened, you can do things like get witness's contact information before they drive away, take pictures of your vehicle and the accident scene before tow trucks come or the cars drive away.
This article in the Atlantic reminded me of why it's so important to document everything, including the accident scene, as you are involved and the dangers of trying to recall this information after the fact. The article discusses three levels of "ability" of the human mind to map. The first, most basic level, is landmarks. Landmarks aren't necessarily mapped landmarks, but personal landmarks to you. For example, you know you need to turn right into your neighborhood because you always go over that speed bump, then pass one street, then you make your left. Those two clues are your landmarks. The second level is routes. Once you master your personal landmarks, you can say, I'll go from that stop sign to the speed bump, pass the street, then I'll be at my destination. You can even offer these directions to others. Beyond the routing ability is the surveying ability. This is when your mind can produce a comprehensive map of the whole area.
This survey level of information is what is most helpful in describing a scene to an insurance company or jury. But it's also the hardest for us to do naturally. So, the lesson: document your accident scene and preserve evidence to help yourself remember details you might not otherwise recall.