elaboration

As an FYI, this post is not about anyone who would be reading this post. A while back someone was telling me about a documentary that he had seen on a cable channel. I recalled that this person had described this documentary before. I also recalled that I had seen the documentary. What was funny was that this person got a lot of the general points about the documentary correct, especially when considering everything that a person could distinguish visually in the documentary. At the same time, this individual got a good chunk of the data that the narrator relayed wrong.

I am not trying to judge. I think I do the same thing, perhaps even unknowingly. I am just intrigued by how the brain not only allows this sort of thing to happen, it really encourages the behavior.

Humans take in a staggering amount of data during the day. Some people are better at remembering it than others. Unless a person has a very specialized condition, his or her subconscious brain is going to have to make the choice about what data is important and what data can be dropped (or at least rendered difficult to access). This is why a typical person can read even a short story and miss many of the major details in that story.

What interests me most, though, is not that the brain does not allow ready access to all of the data that we have taken in. I am actually blown away by the fact that the brain is prone to fill in the gaps on the stuff that we don't remember. If I do not remember some of the elements of a story that are important to the plot, for example, I am prone to subconsciously create my own elements when explaining that story to fill in the gaps in my memory. I may or may not consciously know that I just mentally filled in a gap in my memory with concocted data, but it isn't difficult to convince myself that what I added to the story was actually already there from the beginning.

I think this tendency is why eyewitness testimony is notoriously unreliable. A victim or bystander can become convinced that some specific individual was the person who committed a crime because that individual has specific features that are similar to the actual perpetrator, and the witness just mentally filled in the gaps on some of the other features that his or her brain decided were too unimportant to store. It's possible I am remembering this all wrong, though.