Tuesday, January 16, 2007

wait, what did you just say?

Remember this sequence: 1 cherry 45 chair

If you remembered everything that ever happened, and perceived everything on this earth there was to perceive, you would be either or both: completely crazy, or a super human.

Your brain is very good at filtering out things. White noise (fans in the room, industrial lighting, your nagging in-laws), light, sensations (that pebble in your shoe you got 3 miles ago but weren't able to get out, the tag that itches), and even individual words.

Without looking, what was the very first word I wrote? What was the last sentence of that clause. Can't remember? Can you remember the context of that sentence?

This is known as working memory. It's kind of like the RAM in a computer (or, RAM is kind of like this, since we've been around much, much longer). It's a cache of random bits that you actively hold in your head. How does this apply to my Div3? You generally do not remember the words of a sentence, rather the sentence as a whole.

But what if that sentence doesn't make sense? Ah, here's where it gets complicated.

There is ample data that suggests those who can remember more items in their working memory (words, numbers, shapes, locations are all things you hold in your memory) are better comprehenders of language. They can untie linguistic knots such as: "The horse raced past the barn fell." Or "He was kind of spooked out so he went to the closet where his baseball equipment was. He saw a bat, it was brown and flying about the ceiling." I, of course, am copying this all from my own memory, so it probably doesn't matter.

What was the first sentence of that last paragraph?

Working memory has rapid, rapid decay. What was that sequence I asked you to remember at the top of this entry?

Oddly, there is weird evidence that suggests that the more you use it, the better you get. In my own experiments, the average college student figures out tricks to remember things more and more as we go along. But that's a whole other story.

There are three parts of the working memory system, as it stands. There have been variations and violations, but this is a theory that is generally well supported, and there has been neurological evidence that supports it, as well. One is the articulatory loop, the other the visuo-spatial sketchpad. These go into the central executive. The central executive does things like hold onto it, process it by retrieving things from other parts of memory (definitions of obscure words, whatever the last phrase might have said). The visuo-spatial sketch pad holds objects themselves in working memory: where you just put the keys down, the order of the piles of index cards in front of you).

1 cherry 45 chair


Working memory improves from childhood to adulthood. Look at babies' difficulty with object permanence (playing peak a boo is hilarious to a baby, for instance) compared with an adults complex knowledge of where everything in their life is located. This, of course, degrades after around age 21. But it peaks at 18, and plateaus until a graduale drop-off.

So in conclusion, working memory is essentially incredibly short-span memory. Short term memory is longer than WM. WM only holds about 6-7 items, and degrades as the brain's resources are drawn.

For further information, read:
Baddeley, AD (1986) Working Memory. Oxford Press, England.

More detail to follow, especially on development of working memory.

4 comments:

Shauna said...

So working memory is like RAM if you have the faultiest. computer. EVER.

I understand the second sentence (though it took me a little while - didn't the working memory thing you piloted on me say I was just average?) but how does the first one work? Is it missing a comma?

Moose said...

oh erik more brain games please

Nemo85 said...

Shauna-

It's mostly like RAM. You were an expected average at the time. There is now a very broad curve, and the average has been lowered to about 80%, pushing you well above. But I haven't calculated that out. Since piloting, I've controlled for syllables and fixed a few things. My research assistant is currently figuring all that out.

Shauna said...

I'm so jealous of your research assistant! It's nice to know I'm above average.