GUEST: Memory & Declarative Information (Dr. John Medina).
Excerpted and transcribed from Dr. John Medina’s keynote lecture.
“We live in a multi-cultural world. Does that mean we also have a multi-cultural brain?”
2010 PNAIS Fall Educator’s Conference October 8, 2010 at Catlin Gable School
The following is from Dr. Medina’s Q&A session after his main address it was in response to a question from the audience about the value of reading a textbook chapter once.
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The question is, if you read a chapter once, is it any good? What do we do with the clutter situation in this case?
There are many memory gadgets within the brain that only partially work with each other. So if you ever attend a conference by a non-brain scientist and they say “this is how memory works,” I want you to run out of the room, okay? Or at least stop your ears.
Because memory systems are not understood as a single unit. There’s no hard drive in the brain for memory...there are twelve different memory gadgets within the brain that exist, that operate in a semi-independent fashion. Where you learn to ride a bicycle is not in the same place that you learned that the Battle of Hastings took place in 1066. Those are separate memory systems..
So, we have to talk about one memory system. Let’s talk about reading a chapter. Being able to read a chapter and regurgitate it isn’t what education is about. But it’s a simple figure that can be measured in a laboratory. It’s called declarative information. The Battle of Hastings in 1066 is about something you can declare. Six times seven is 42 is something you can declare. It’s used a lot in classrooms. What do we know about the declarative memory system within the pantheon of twelve memory systems? Here it is:
You can hold seven pieces of declarative information for 30 seconds. If you don’t repeat it, the brain will toss it. You have 30 seconds to hold it. This is called immediate memory. If you don’t repeat it within 30 seconds, it will go away. If you do repeat it within 30 seconds, it goes through another buffer, where it will reside for approximately two hours. It will now reside in your head for two hours. So if you pass the 30 second mark, it will now go into this buffer called working memory. If you don’t repeat it within two hours, the brain will chuck it again! It will get rid of it! Most of human learning is controlled forgetting, which is why forgetting is as as much a part of the process as active learning is.
If you don’t repeat it within two hours, it will go away. If that’s the case, homework is not review, if it is way past the two hour mark. Homework is new learning, as far as the brain is concerned with declarative information.
If that were the case, it begs a great question for brain scientists and education professionals whenever we get together. You know what I do? I take a standard 60-minute lecture in high school - say there are normally six periods in this school, where you have 1-2-3-4-5-6 hours of unrepeated, declarative, firehosed information!
Instead, what if we did this: what if we busted that 60 minutes up into three 20-minute segments and then repeated each those 20-minute chunks every two hours throughout the course of the day? Over and over and over again, where there was constant repetition. Where you captured not only that 30-second gauntlet, but the two-hour gauntlet. Would that work? Would that obviate the need for homework?
Tons of standardized testing has occurred throughout the land. Most brain scientists go, “And what is this based on again?” No matter what we do, we ask that question a lot. If that’s the case with declarative information - you have 30 seconds, you have two hours...notice what I was saying, if you do repeat it within two hours, you have recruited it for long-term storage so that you might need it for a standardized test. But note that I said recruited. I didn’t say sorted. The question I will ask rhetorically is:
How long does it take after you’ve gone through 30 seconds, and you’ve gone through two hours, and all the repetition has occurred, how long does it take for that declarative memory trace to fully consolidate into the brain, such that it is infinitely retrievable, and not subject to corruption at retrieval? How long does it take?
Does it take a day? Does it take a week? Does it take a month? I will tell you how long it takes. Now this is declarative memory only. It takes about a decade. It takes ten years. It’s called systems consolidation and the guy’s name is Bob Stickgold. Systems consolidation. For declarative memory. Ten years. And in those ten years, it is not infinitely retrievable and it is subject to corruption. You know what that means?
It means that if somebody has learned something in the First Grade, they have not consolidated a unique declarative memory transfer until they are a Sophomore in high school. And, by the time they are a Senior, you are not graduating a Senior, you are graduating a Fourth Grader!
And if that’s the case, I have a research suggestion.
I’d do something like this: what if treated important important bodies of knowledge the same way we treated booster shots? And every year, just go ahead and revisit it. Stuff that’s already been learned. I would argue...a real good example: in Sixth Grade math, you have fractions. They seem to be a big deal. Why not repeat fractions over and over again from Grades Four to Six? If it takes ten years anyway, why not give it a course correction? That is research question. We don’t know what the answer to those questions might be, but the Ten-Year Journey is not an opinion, it is actually how the thing works.
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*loosely transcribed by Joseph Long