Retrieval: Getting and Forgetting (Part 8 of 14)

What saves our sanity, every day, is that we can forget.  It’s good that we forget things--even though sometimes we forget more than we want to--for if we never forgot anything we ever thought or saw, we’d drown in the information overload.

For teachers, all this forgetting means that even if we sustain our students’ attention, even if we help our students encode information richly, and even if we create opportunities for students to consolidate that information in their minds--they will still naturally forget things.  Like patterns in sand on the beach that wash away, so will memories.

And it turns out that the rate at which we forget things has been studied.

Forgetting and Remembering

In the late 1800s, a psychologist named Hermann Ebbinghaus tested peoples’ memories for both meaningless and meaningful information over time, and he developed curves that showed our rate of forgetting information.  (Ebbinghaus is that guy pictured above...)

We lose information really fast!  This graph shows the rate of retention for nonsense information; within an hour, more than half is gone.  Within 24 hours: two-thirds.  Meaningful information sticks around longer, as we'll see in a moment, but memory still degrades.  

It turns out, though, that we can help information live longer in our brains by bringing it back to mind--by retrieving it.  If we do this, the curve of our forgetting changes, and our expectation for long term memory can increase.

Imagine you learn something so that you can repeat it from memory.  As we saw above, your memory of it will naturally deteriorate over time.  The curve above shows what happens if we learn it fully again, one day later.

We can see here that after studying it a second time, the curve flattens out at a higher level.  This represents how, over time, we retain a greater amount of the information as a result of the second learning.  And, if we repeat the process of learning again--if we study the material a third time--then the curve shifts again, and our long term retention includes an even greater percentage of the content.  See here:

And so, the more times we review and relearn the information, the more of it we retain over time.

How many repetitions are best?
In addition to measuring how much information we lose from memory after periods of time, Ebbinghaus also measured how many times he had to repeat something in order to fully commit it to memory.

To test this, Ebbinghaus practiced memorizing meaningless information (sequences of nonsense syllables), and meaningful information (eight lines of a poem by Byron).  He would read and recite the material again and again until he could repeat it all, entirely from memory.  At this first go around, he counted how many times he had to repeat the information before he could recite it perfectly from memory.

By the next day, he would have forgotten much of what he had studied.  So, that next day, he would try again with the same information--and he would again measure how many times he had to repeat/rehearse/practice the information before he could do so without prompting.

And then, a day later, again.

And each day took fewer and fewer tries:

Each line above is a different body of information, and the vertical axis shows how many times Ebbinghaus had to repeat the information in order to commit it to memory.  The largest amount of nonsense information naturally takes the longest.  Notice how the poem from Byron takes the fewest repetitions, even at the outset--and even though eight lines of poetry is far more content than even the largest amount of nonsense information.  This is because he can encode the information from the Byron poem more richly and easily; it has meaning, and he can attach the words and images in the poetry to stories and imagery in his mind, to prior knowledge that he has.  By day five, in fact, he needed no prompting at all, having fully committed the verse to memory.

Now remember the previous posts about how memory works: retrieval is the stage of learning when we reach into our long-term memory to pull thoughts back into consciousness, back into working memory.  Knowing what we now know about the brain, we can see that when we recall information, we send signals through the networks of neurons we’ve formed, through the pathways that have been forged throughout the brain.  Remember the desert image; we run water across the sand, and it travels across paths and rivulets it had previously carved, both re-visiting (remembering!) them and deepening them, making them easier to access the next time.  This is retrieval.

~

And so, work by Ebbinghaus and others offer us three specific takeaways about retrieval:

First: retrieval strengthens memory.  This is the lesson from Ebbinghaus: the more we bring something to mind, the stronger it becomes in our memory.  The simple act of thinking changes our minds.  And as an understanding of encoding shows us, this is particularly true if we retrieve memories in order to connect them to something new.  Simply bringing something to mind strengthens its impression, and associating that memory with something new strengthens it even further.

For this reason, it's helpful to do something with memories or pieces of information when we retrieve them: rearrange or reorganize them, write about them, talk about them with somebody, etc.  Remember the diagram about working memory and long term memory.  Retrieval pulls information out of long-term memory, cycling it into working memory and re-encoding it with any new, additional information.  We are elaboratively building associations, forming new networks of knowledge and thought.  

Second, the organization of encoding influences retrieval.  If your brain were a bookshelf, and you’re trying to find a book, then if the books were stacked all willy-nilly, it may take some rummaging around to find what you’re looking for.  But, if you’ve organized the books on your shelves, then the one book will be much easier to find.  For instance, if you choose to organize your shelf by the length of the title, with one-word titles on the left, then retrieving your book of choice will be much easier.

So it is with cognitive retrieval.  If you’ve associated memories with similar memories by making connections between them, then they’ll be easy to find.  If memories have been stored in isolation, or were not stored deliberately at all, then they may be hiding off in a dusty, shady corner somewhere.

The third takeaway, though less discussed here, is: our environment influences our retrieval.  Stress and emotion can stifle our ability to easily recall what we know.  Calm and space can promote effective retrieval.  We’ve all experienced this: when under time pressure, that elusive fact or idea can seem tantalizingly far from reach, but when we’re performing some routine task later on, that elusive fact we were looking for pops into mind.  In this way and others, the various pressures and expectations of our environments can influence our retrieval in numerous ways.  Much is written about this, and if it’s a topic of particular interest, the book “Choke” by Sian Beilock, offers a great overview.

Overview

As teachers, then, we can craft our student experiences in ways that amplify the benefits of retrieval so that the habits, skills, and information we promote in classes can more readily transfer into their lives.  In our planning, we want to offer regular retrieval opportunities for our students to strengthen their memories, we want to ensure that we promote organized encoding so that students can access their learning more readily, and we want to be sure that we create a safe and non-threatening environment in our classroom spaces to facilitate both their encoding and retrieval.

This is the fourth stage of the cognitive model for educators: attention, encoding, storage, and retrieval.  In the remaining posts we’ll look at the implications and opportunities that arise from this framework, starting in the next post with how this framework directly informs our day-to-day planning and teaching.  

This is the eighth of fourteen posts on the role of cognitive science in education.
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Introduction:

• Cognitive Science: The Next Education Revolution (Part 1 of 14)
• A Cognitive Model for Educators: Attention, Encoding, Storage, Retrieval (Part 2 of 14)

The Science:

• Attention: the "Holy Grail" of Learning (Part 3 of 14)
• Encoding: How to Make Memories Stick (Part 4 of 14)
• (Interlude) Long Term Memory and Working Memory (Part 5 of 14)
• Storage I: How Memory Works - Redux (Part 6 of 14) 
• Storage II: Sleep and Memory (Part 7 of 14)
• Retrieval: Getting and Forgetting (Part 8 of 14)

Implications and Opportunities:

• Cognitive Design: Essential Questions for Educators (Part 9 of 14)
• Character and Success... and the Cognitive Model (Part 10 of 14)
• Towards a Unification of Pedagogies (Part 11 of 14)
• Why Old School and New School Aren't in Conflict (Part 12 of 14)
• Technology, The Brain, and Teaching (Part 13 of 14)

Conclusion:

• Manifesto: The Art and Science of Education (Part 14 of 14)

Image of Hermann Ebbinghaus from Wikimedia Commons