Have you ever been sitting minding your own business when a smell suddenly transports you back in time to a place you'd almost forgotten and a scene from the past replays in your mind in amazing detail? Did you then stop to wonder just how you were able to recall so much from so long ago?
The human capacity for memory is immense. As I've already mentioned in this series, we can remember the key identifiers for thousands of faces and that's just one of the things we keep in our memories. We store images and events from the past in minute detail; vast amounts of information on a wide range of subjects we learnt at school or picked up through work; languages; songs; books - the list goes on and on. The average person stores memories over a period of sixty years or more. If you were to try to express that in terms of computer storage, the number of bytes required would blow your mind.
Of course, storing huge amounts of data isn't the whole story. It's worth nothing if you can't get at it and the data retrieval mechanism in the human mind makes Google look slow and horribly inaccurate.
The human memory works most effectively by association (i.e. attaching the whole event to a significant object or sense). That's how that smell triggered off a long forgotten memory. It works with songs, pictures, sounds, tastes - all sorts of things. This is also how you remember things with mnemonics. One of the techniques for improving your memory and recall is to think of a number of ordinary objects (rooms in your house, for example) and picture one of them with each thing you want to remember. Then, to later recall it, you only need think of the associated object.
That technique works very well and gives us some of our strongest memories but it certainly isn't the way we remember everything. For example, how is it that I know that the capital of Mongolia is Ulan Bator? I've never been there and don't have any strong connections with the fact but, nevertheless, I can remember it easily. Having heard it repeated a few times, I now find it's one of those pieces of trivia that I simply know.
Memory is one of the most mysterious processes that goes on inside us but at the same time it is one of the most important. I happen to think it is also the basis for our intelligence and is therefore indispensable.