Skip to main content

Retrieval: Getting and Forgetting (Part 8 of 14)

Ebbinghaus and Forgetting
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...)
Ebbinghaus Forgetting Curve
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.
Ebbinghaus Forgetting Curve
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:
Ebbinghaus Forgetting Curve
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:
Ebbinghaus and Repetition
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.
Book stacks and Book shelf
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.

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.
Lessons from 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.
To have future posts delivered to your inbox, choose “subscribe” from the bar on the right side of the screen.

Image of Hermann Ebbinghaus from Wikimedia Commons
blogger analytics


Popular posts from this blog

Four Ways to Measure Creativity

Assessing creative work has been a bugaboo for a good long time.  In schools it's the constant refrain: “How can you grade creative writing?”  or “It’s a poem: however it comes out is right.”  In businesses and elsewhere, people demand innovation--and are stymied with understanding how to measure it. But this is not the bugaboo we think it is--in the classroom, or in the broader world of creative work.  Here are four different ways to assess creativity, each designed for different settings: 1. Measuring How Creative a Person Is - The Guilford Model 2. Measuring How Creative a Work Is - The Taxonomy of Creative Design 3. Measuring Creative Work Against a Program - The Requirements Model 4. Measuring the Social Value of Creative Work - Csikszentmihalyi’s Model Notably, in each of these cases, what we mean by "creative" changes a little.  Sometimes "creativity" refers to divergent production (how much one produces, or how varied it is).  Sometimes "c

Taxonomy of Creative Design

Strategies to improve creativity are many, but they are also diffuse.  Little ties them together in a way that offers a coherent vision for how creativity can be understood or developed incrementally.  The Taxonomy of Creative Design, a work in progress, offers a new theory for doing so. Since creative work can be measured along spectrums of both and form and content, the Taxonomy of Creative Design offers a progression from imitation to original creation measured in terms of form and content.  In doing so, it organizes creative works into an inclusive, unifying landscape that serves not only as an analytical lens through which one might evaluate creative work, but also as a methodical approach to developing creative skills. Here is a closer look: Imitation Imitation is the replication of a previous work.  It is the painter with an easel at the museum, painting her own Mona Lisa; it is the jazz musician performing the solo of the great artist note for no

A Cognitive Model for Educators: Attention, Encoding, Storage, Retrieval (Part 2 of 14)

So how do  people learn?  What are the mechanics of memory?  Can we distill thousands of articles and books to something that is manageable, digestible, and applicable to our classrooms?   Yes.   In brief, the cognitive process of learning has four basic stages: Attention : the filter through which we experience the world Encoding : how we process what our attention admits into the mind Storage : what happens once information enters the brain Retrieval : the recall of that information or behavior Almost everything we do or know, we learn through these stages, for our learning is memory, and the bulk of our memory is influenced by these four processes: what we pay attention to, how we encode it, what happens to it in storage, and when and how we retrieve it. Here’s a closer look at each: Attention: We are bombarded by sensory information, but we attend to only a small amount of it.  We constantly process sights, sounds, smells, and more, but our attention se