How Memory Works: A Classic Model Explained

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How Memory Works: A Classic Model Explained

Educational Psychology · Chapter 2: Memory, Thinking, and the Learning MindSection 2.2 · lesson 7 of 1009 min · free with a free account

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In this lesson

The Atkinson-Shiffrin multi-store model, and the two gates it identifies.

  • Describe the three stores of the Atkinson-Shiffrin model
  • Compare capacity, duration and encoding across the stores
  • Distinguish maintenance from elaborative rehearsal
  • Explain how retrieval returns information to working memory

Transcript

Everything said in the video, section by section (1,214 words). Read along, or search it.

Memory, Thinking, and the Learning Mind

How Memory Works: A Classic Model Explained

You can hold a phone number in your head just long enough to dial it. You can also recall a childhood address you have not used in twenty years. Those two facts do not fit inside one system. In nineteen sixty-eight, two psychologists explained why. This section covers the Atkinson-Shiffrin multi-store model of memory. It proposes three separate stores, each with different properties. We will look at the capacity, the duration and the encoding of each. We will see what moves information from one store to the next. And we will find that two gates control the whole system. Attention, and rehearsal. Both of them are things a teacher can influence.

The Proposal

Three Stores, Not One Memory

In nineteen sixty-eight, Richard Atkinson and Richard Shiffrin published a model. It became one of the most influential accounts of human memory ever proposed. They called it the multi-store model. Memory, they argued, is not one thing. It is three distinct stores. The sensory register. The short-term store. And the long-term store. Each differs in capacity, in duration, and in the type of encoding used. Information flows sequentially from one store to the next. And here is the consequence that matters for teaching. The path a piece of information takes determines how long it survives. Seconds, or a lifetime. Same lesson, different route.

Why It Mattered

A Structure That Explained the Puzzles

Why was this model considered groundbreaking at the time? Because it gave a structural explanation for things that had resisted explanation. Take the first puzzle. Why can we remember something we just heard for only a few seconds? Unless we rehearse it, in which case it lasts. Now take the second puzzle, which points the other way. Why do some memories persist indefinitely while others fade almost instantly? A single-store account struggles with both of those at once. Three stores with different properties handles them easily. Later research has challenged and refined parts of this model. It remains foundational in cognitive psychology and in educational theory. It is the map that everyone still argues against.

Store One

The Sensory Register: Wide and Brief

Start with the first store, the sensory register. It is the entry point for all external information. It holds sensory impressions in their raw, unprocessed form. And it holds them for a very brief duration indeed. Visual information lasts typically less than one second. That is iconic memory. Auditory information lasts roughly two to four seconds. That is echoic memory. The capacity of this register is large, which is easy to misread. Large capacity, but ruthless decay. Information vanishes rapidly unless attention is directed toward it. Only a small fraction of sensory input moves forward into the short-term store. Everything a student does not attend to is gone within about a second.

Store Two

The Short-Term Store: Small and Fragile

The second store is where conscious awareness actually lives. The short-term store holds what you are thinking about right now. It has two limits, and both are severe. The first limit is capacity. About seven items, plus or minus two. That figure was established by George Miller, and it has become famous. The second limit is duration. About fifteen to thirty seconds without rehearsal. Put those two together and look at a typical classroom. Every instruction you give competes for roughly seven slots. Those slots empty in under half a minute. A three-step task, delivered verbally, with a board full of text behind it, is asking a system with hard limits to do something it cannot do.

Rehearsal

Two Ways to Hold On, One That Transfers

So how does information stay in short-term memory at all? Through rehearsal, and there are two kinds worth distinguishing. Maintenance rehearsal is simply repeating information mentally. It is the primary mechanism for keeping something alive in short-term memory. Elaborative rehearsal is different. It connects new information to existing knowledge. And it is far more effective for transferring information into long-term memory. Here is the distinction most students never make. Maintenance rehearsal keeps something available for now. Elaborative rehearsal is what makes it durable. Repeating a definition twenty times is the first one. It feels like the second one, which is exactly why students keep doing it.

Store Three

The Long-Term Store: Effectively Unlimited

The third store is the long-term store. It is the permanent repository of everything an individual has accumulated. Knowledge, skills, and experiences. Unlike short-term memory, its capacity is effectively unlimited. And it can retain information indefinitely. But raw capacity is not what makes it useful. Information in long-term memory is organized. It is held in semantic networks and conceptual frameworks. Retrieval becomes more efficient when new learning connects meaningfully to old. So the size of the store is never the constraint on learning. The quality of its organization is.

The Flow

Sensory to Short-Term to Long-Term

Let us walk the flow once, end to end. Information arrives at the sensory register in raw sensory form. Capacity is very large. Visual traces last under a second, auditory two to four. Attention gates the first transition, into the short-term store. There, capacity drops to about seven items, held for fifteen to thirty seconds. Encoding there is phonological or visual, and it is conscious. Rehearsal gates the second transition, into the long-term store. There, capacity is unlimited and duration is potentially permanent. Encoding becomes semantic or procedural, held in networks of meaning. Two gates control this entire system. Attention opens the first. Rehearsal opens the second. Both of them are things a teacher can design a lesson around.

Side By Side

The Three Stores Compared

It is worth holding the three stores side by side. The sensory register. Very large capacity, and a duration under one second for vision. Two to four seconds for hearing. Encoded in raw sensory form. The short-term store. About seven items, plus or minus two. Fifteen to thirty seconds without rehearsal. Encoded phonologically or visually. The long-term store. Unlimited capacity, potentially permanent duration. Encoded semantically, or as procedures. Now read the middle row again, because it is the teaching bottleneck. Every new idea has to survive a store that holds seven things for half a minute. Everything you know about pacing, chunking and repetition follows from that row.

Retrieval

The Flow Runs Both Ways

One more feature of the model deserves attention. The flow of information is bidirectional. Information generally moves from sensory register to short-term to long-term. But retrieval reverses the direction. It brings information from long-term memory back into short-term memory. Short-term memory in that active role is often called working memory. And this is where the model earns its keep. Retrieved information can be combined with newly encoded material. That combination is what makes complex cognitive tasks possible. Problem-solving. Reasoning. Anything that requires holding two ideas together. Which is another reason prior knowledge matters so much. A student with nothing to retrieve is doing the task with half the machinery.

In Practice

Three Words on a Board

Watch the whole model run inside one ordinary teaching moment. A teacher writes three key vocabulary words on the board. She pronounces them at the same time, so the words arrive visually and aurally. Students who pay attention move those words into short-term memory. Students who do not have lost them within a second or two. Nothing about the teaching differed. Only the attention did. Then she asks students to use the words in sentences. That request forces elaborative rehearsal. The words get connected to meaning, and the likelihood of long-term storage rises. Notice what the teacher could and could not do here. She cannot force encoding to happen inside a student's head. She can design a task that makes elaborative rehearsal the natural response.

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FAQ

Questions students ask us

About How Memory Works: A Classic Model Explained

What is the Atkinson-Shiffrin model of memory?
The Atkinson-Shiffrin model, published in 1968 by Richard Atkinson and Richard Shiffrin, proposes that memory is three distinct stores: the sensory register, the short-term store and the long-term store. Each differs in capacity, duration and type of encoding, and information flows from one to the next. Later research has refined parts of it, but it remains foundational in cognitive psychology.
How do the sensory, short-term and long-term memory stores differ?
The three stores differ sharply in capacity and duration. The sensory register has very large capacity but holds visual traces for under a second and sounds for about two to four seconds. Short-term memory holds about seven items for fifteen to thirty seconds without rehearsal. Long-term memory has effectively unlimited capacity and can hold information indefinitely, organized by meaning.
What is the difference between maintenance and elaborative rehearsal?
Maintenance rehearsal is mentally repeating information to keep it active in short-term memory, while elaborative rehearsal connects new information to existing knowledge. Maintenance rehearsal keeps something available for now, but elaborative rehearsal is far more effective at transferring it into long-term memory. Repeating a definition twenty times is maintenance; using a new vocabulary word in your own sentence is elaborative.
What moves information from one memory store to the next?
In the multi-store model, two gates control the flow: attention moves information from the sensory register into short-term memory, and rehearsal moves it from short-term into long-term memory. The flow also runs in reverse, because retrieval brings long-term knowledge back into short-term memory, often called working memory, where it combines with new material for reasoning and problem-solving.

About the Educational Psychology course

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Educational Psychology (Psychology 120) carries a NCCRS credit recommendation for 3 semester credits. ACE and NCCRS have over 2,100 cooperating colleges that will consider accepting credits; the final decision is with the universities.
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