Why we forget

In trying to remember the reasons why we forget I've probably forgotten some, but there are many reasons, some physical some mental and some between the two. 

1. Because the brain leaks.  I don't know if this is true but I think of the film called The Navigator, where a small boy is taken in an alien space craft only to find the space craft had momentarily kidnapped him to put maps in his head.  His brain was fallible and they crashed, because the maps leaked.

2. There isn't enough motivation.  But I'm not sure if this is a valid reason. You could be motivated with a golden pot to remember something but still not remember it.  It's all about a)storage, b) coding and c)retrieval.

3. The engram is not strong enough. One theory is for every memory a physical trace exists in the brain termed an engram.  If this physical trace is not excited enough by the process of remembering it fades away.

4. The memory is there but, it's a retrieval problem. In trying to remember something you may have to think around the item needed to remember. It's like a word you don't use much in your vocabulary but when you want to pull it out of memory it just doesn't pop up.  Otherwise known as being on-the-tip-of-your-tongue. Thinking about something can side step into the item needed. The Critical Incident Interview  (CIT) method is one way to help witnesses recall and event by focusing on a variety of factors which surround the event.

5. Repression. Likely an explanation with psychoanalytic origins.  The mind (unconscious mind) pushes a memory out of consciousness, because it doesn't like it and chooses not to think about it. This is a coping mechanism for unpleasant things. Psychoanalysis helps to bring these to the surface, a safe environment is necessary and a willingness to face something unpleasant.

6. Suppressed memory. I must admit to suppressing a memory once, this is something you consciously and willfully do.  It is chosen unlike repression which is not chosen.  I did this to remove from my memory the phone number of one of my first girlfriends.  I thought about it and made myself forget it, I wanted to get her and it out of my mind. I could not forget her but I sure as hell forgot her phone number and it didn't take too long either.  I suppose some items of memory can never be forgotten, but at least with the hindsight of maturity their meaning or pain diminishes a lot.

7. Poor memory cues.  Like the CIT method, a memory is still there but the issue is retrieval, because there is not a strong enough thread it can't get pulled out of your mind.  In open brain operations where patients have had their cortex stimulated they have been able to recall events they had long since completely forgotten.  This may suggest in fact everything which ever happens to an individual is stored as a memory in the brain.  The film Rain Man comes to mind, this was based on a real savant who could remember everything but knew the meaning of nothing. e.g. could recite a pack or multiple packs of shuffled cards with ease but not tell you the price of a hamburger in understanding the concept of money.

8. State related memory.  Sometimes it helps to be in the same emotional, psychological or physical state as the memory was created to recall it.  There is a Charlie Chaplin film where he makes friends with a millionaire drunk, but as Charlie was himself drunk at the time he only realises the drunk is his friend when intoxicated again.

Well these are most of the items which came to mind at the time of writing this BLOG, I've tried to put them into easy to understand terms because most of the technical terms I've forgotten, but can easily be picked up from an internet search or an enquiring mind.  I should of remembered to create a mnemonic, unfortunately the effort of doing mnemonics is still too much. Luckily my head is screwed on.