Saturday 16 November 2002

Pic of the day: A photograph from this spring. But can I remember this spring? Uh, eh ... it was like all the other springs recently, wasn't it?

Why we forget

Yeah, the summer's gone
But a lot goes on forever
And I can't forget, I can't forget
I can't forget but I don't remember what

Leonard Cohen, I can't forget from the album I'm your man.

From time to time, popular science magazines and books go wild about the capacity of the human brain. It is as if nothing is impossible, least of all remembering everything in our life. This is backed up with case stories of a few people who seem able to remember impossible amounts of useless detail. And yet most of us forget almost everything we learn. Why, oh why?

First off, memory may have survival value, but it doesn't increase in proportion to how much we can remember. It is essential in a modern society to remember a lot of skills, and master a language or two. But not to remember the exact clothes people wore on any particular day. It may impress that special someone, but it won't give you any "evolutionary benefit" unless you're already good-looking.

Second, forgetting may actually make it easier to get to the stuff you really need to know. After all, we have a limited attention. This varies much less than recall. We can only be aware of so many things at any one time. If we have a pretty good idea of what we need to know, forgetting the rest actually makes our day easier.

Small children can learn random facts with ease. Then again, small children don't know what will be important and what not. As we grow older, we have a pretty good idea about what we need to know, and can safely forget those things that don't fit in. It makes for a more streamlined mental process. Then again, it is my personal opinion that most people take this too far. They lose the childlike sense of wonder, the ability to ask "Why? Why? Why?" and to believe two seeming contradictions. Older people tend to stay within their circle. Christians read Christian books and newspapers and go to church on Sunday. Non-Christians do none of the above. Same goes for political parties, for those so inclined. Painters don't compose. We specialize – because life is too short. A shame, isn't it? Especially when we specialize so much that we eventually stop living while still alive.

***

We can think of memory as having 3 stages. First there is the immediate memory, where we store a phone number we're only going to call once. It is commonly said that this memory can only hold 7 items, but each of these can be a pointer to a fairly complex memory or concept. So unless you are mathematically inclined you may have to mumble under your breath to call an 8-digit number. (And indeed, the phone numbers here in Norway have 8 digits, and people do call wrong number a lot. I don't know if this is intentional to get some extra revenue – we are not more than 9.999.999 people here and won't be for a few more centuries, it seems.)

After the immediate memory comes the short-term memory. It is probably caused by electrochemical activity in the brain, because unlike long- term memory it is erased in whole or in part by electroshock therapy or severe concussion. Contrary to earlier belief, it now seems that we don't remember everything we see, hear, smell, taste and touch. It doesn't even make it to the short-term memory. We only remember what we have noticed, what we have been aware of. This is not so big a loss as it would seem: The things we notice tend to be the new ones, or the action. Things that just stand there don't get noticed, especially if we have seen them before. Why remember the same things over and over again?

Somewhat to the disappointment of a lot of people, it turns out that most super witnesses make up the intricate details they report. Even if you have eidetic memory ("photographic memory"), you still only remember what you focus on. Again this usually works well enough, because we tend to use stereotypes when we fill in. And stereotypes are usually true, which is why they became stereotypes in the first place. But sometimes it can go horribly wrong. In the USA, for instance, if there is a racial mix at the scene of crime, it is not uncommon to swap the colors of the implicated to fit with the stereotypes. Intriguingly, this tendency is no less among the ethnic minorities there. I suspect the same would happen in any other country with racial / ethnic differences.

***

It seems that all of our short term memory is indeed stored as long term memory; but not all is indexed. People with severe damage to the hippocampus are unable to remember things that happened after that damage. However, with electrical stimulation of the brain there can be brought forth memories regardless of whether they are before or after. Sadly, electrical stimulation only causes random memories. We have no idea whatsoever as to how the brain indexes its memories! This would be truly useful. But it does not seem to follow any neat system.

We know a bit about how we can remember a fact or incident better. Since education is so important these days, there has been a lot of study on this. For most people, the key element is repetition. Repeating a fact after 20 minutes, 1 day, 1 week and 1 year should do. If that's not enough, you may want to double it, adding 40 minutes, 2 days, 2 weeks and 2 years. Though how you will remember to repeat something after 2 years if you don't remember it already is quite beyond me. ^_^

Other ways to remember better is to get plenty of sleep (dreams do wonders to connect memories, and memories live by connection). Drinking coffee also seems to help, not to remember old news but to burn in new ones. This is probably because coffee strengthens awareness, and awareness determines how much we put into short term memory in the first place. But this is pure speculation on my part. It would be interesting to give people coffee 20 minutes after they study and compare to those who get the coffee first. I'm not volunteering, though, because I react rather badly to coffee. Perhaps some of my readers?

***

The key to memories seems to be this, that they live by connection. A memory that is connected to active memories is itself recharged, as if some of the energy flows over from the memories that surround it. A memory that is cut out of the loop, withers and dies. And we do this a lot to our memories. It is a habit, and one that serves most of us well. Many memories float around in the subconscious. If they are internally connected to each other, they may make up a "complex", a kind of primitive miniature personality, especially if they have an emotional component. These complexes may show up as characters in our dreams (or novels), or as voices in our heads if we are unlucky. If we have a strained relationship with a complex (for instance, it is banned from our personality because it did not fit our self-image) there can be a tug-of-war with the memories. The complex may claim some memories and we know they are there, but we cannot for our life get to them. Yes, the complexes do that to spite you.

When we grow old, we start to forget a lot. But intriguingly, we also start to remember things from our childhood that we thought we had forgotten. My pet theory is that this is evolution in action: The elders of the tribe were the library, until writing was invented. By remembering their childhood, they created a continuation of memory across generations. They would even remember what their own grandparents had remembered ... making memory not just a function of the body, but of the society as well. And in many ways, it still is. You forget not just for yourself, but for the benefit of all. Remember this.

(No, I did not forget to put up this entry. I played DAoC all day and all night.)