Here is the full transcript of cognitive neuroscience professor Torkel Klingberg’s TEDx Talk: Improving Working Memory Capacity at TEDxNorrköping.
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Torkel Klingberg – Professor of cognitive neuroscience at the Stockholm Brain Institute
I’m sure most of you are familiar with the situation when you walk into a room, then you stare into the wall, and then you think, “Why did I walk into this room?” So you had a plan, right, just a few seconds ago, you had a plan of what to do next, but somehow you lost it.
So there is a special kind of memory that’s supposed to keep plans like that in mind, and it’s called working memory. It’s a very useful kind of memory. You use it not only to remember plans and instructions, but you also use it to keep in mind relevant information when you solve problems. So it’s very important for mathematical problem solving, and it is also closely related to attention. So one way to put that is you need to remember what to focus on.
I’m going to illustrate that by testing your working memory here. So your task here is to remember where this person is pointing so that you can point at the same boxes in the same order, OK?
OK, so now you’re keeping information in working memory, four positions, so that you can do something based on that information, right? Easy enough. Let’s have another one. So the same task: remember where this person points. Any volunteers here, in the first row? So that’s a bit harder. So this illustrates the key problem here, and the key problem is that working memory is limited. Capacity to store information is limited.
If I were to test you, you would remember roughly seven items here. This has been termed “the magic number seven”. It’s thought to be a very important limit on information processing ability of the human brain. But, some of you might remember eight, some of you might remember only six, so, that’s normal. But when you get an unusually low working memory, you run into problems. So children with low working memory capacity, they have problems remembering instructions, what to do next, they are inattentive, they fail in mathematics, they struggle with reading comprehension.
So I said, “We have a problem, and I think I have, a partial, at least, solution.” So I started to study the neuroscience of working memory about 20 years ago, to understand what’s the neural basis for working memory, and what’s the neural basis for these capacity limitations. One finding from our and others’ research is that this is not a global problem all over the brain, but it seems to be restricted to a set of bottleneck areas in the brain and the connections between them. So here seems to be that the processing ability of these regions is also constituting the limitations of working memory.
But on the other hand, we know that the brain is plastic. It can change with training. It can change with experience. For example, if you look at musicians, violinists, you see the brain areas controlling the fingers — they change as a result of practice.
So why wouldn’t you be able to change these regions as well? I teamed up with some computer game programmers to make a program where — a computer program where children could train working memory. So we want them to train on tasks similar to the one that I showed you here, to do that for at least 45 minutes — that’s about how long, time they can manage — and do that five times a week for five weeks. That’s again about as long as they could manage to do this.
Using computer-game-like design made it slightly more motivating. We also could use the computer program to adapt the difficulty level, so it’s close to the capacity limit. That’s a similar principle to when you do physical training. It’s when you’re close to your limits that you can actually change.
Then, we wanted to test the effect of this and we did that in roughly the same way you go about when you want to try out a new drug. You have people randomized to either receiving the treatment — which is the working memory training in this study — or a placebo, which was a computer program where difficulty level was not adapted to the limit of the subjects.
And then you have psychological tests, measuring working memory capacity of the children before and after. So this was a very simplistic idea. This was a neuroscientist stumbling into the field of working memory and treating working memory as a muscle, rather than some magical black box. But it worked.
So when we looked at the test results, we could see that children doing the training, they have actually improved their working memory capacity by roughly 20% to 15%, and this has been replicated many times now. So the magic number seven isn’t so magic, after all.