External events are just that.
For definitions sake, an event that happens in proximity of the observer is an event that the observer personally observes. So this is not meant to be a riddle or anything but it's important to be clear since we're using common English words in slightly different ways. Pretty basic but the distinction will become important in later posts.
This could be anything from a conversation (uninvolved) to a gunshot intending to kill the observer. Events on their own are ubiquitous and range from inconsequential to life threatening. Inconsequential in the sense that though the observer has no real concern or buy in.
A type of “a tree falls in the forest” concept. If the observer is nowhere near the tree she is not affected by this event. There are no experiences or emotional impact. Now, let's say she is in range of this tree fall. Let's say she is in the immediate vicinity, literally there when the tree is falling. She has never experience something like this in her life. The event will be new to her brain (or, to her). Though she may not be in danger or feel particularly uneasy she will be observing this for the first time. Simultaneously, she will lean on her historical collection of data (memory) for familiar experiences and her brain will provide input (or perspective) based on this data (memories). If there are no similar experiences in memory, the brain is going to struggle with identifying the experience and may provide false information. Remember this is taking place while the tree is falling. We're looking at a combination of brain function and memory retrieval .
Now, during this process we have to recognize that before an event occurs memories have been formed in the past that will influence the memories formed immediately after this event is over. In other words, if you experience something terrifying your brain will create a retelling of what happened shortly after the event has occurred (since our brain likes patterns) so that you can identify or categorizing what exactly transpired. That's not very different from how you learn. The event could also be identified as a traumatic, the event does not become an experience until the event is observed with perspective. Your current experience is strongly based on your historical perspective or memories. for you math nerd out there (event + observation) x (perspective + new observation) = experience.
So, there is a lot of detail skipped here but more post to follow. Thanks for reading. Please leave some comments and questions and I'll respond as soon as possible. :)