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Module 4.7: How Memory Functions

Memory is an information processing system; therefore, we often compare it to a computer. Memory is the set of processes used to encode, store, and retrieve information over different periods of time.

Click on the terms in the diagram below to learn more about the functions of memory. Click the "Reset" button to clear the text and start over.

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Link to Learning

Take this survey to see what you already may know about memory. After you complete each question, you will be able to see how your answers match up to the responses of hundreds of other survey participants, as well as to the findings of psychologists who have been researching memories for decades.


Figure 4.12 When you first learn new skills such as driving a car, you have to put forth effort and attention to encode information about how to start a car, how to brake, how to handle a turn, and so on. Once you know how to drive, you can encode additional information about this skill automatically. (credit: Robert Couse-Baker)

We get information into our brains through a process called encoding, which is the input of information into the memory system. Once we receive sensory information from the environment, our brains label or code it. We organize the information with other similar information and connect new concepts to existing concepts. Encoding information occurs in two ways (Figure 4.12):

  • Automatic processing is the encoding of details like time, space, frequency, and the meaning of words. It is usually done without any conscious awareness. Recalling the last time you studied for a test is an example of automatic processing.
  • Effortful processing is the encoding of more complex information and it requires a lot of work and attention on your part. Remember what you studied the last time you studied is an example of effortful processing.

Memory Exercise

What are the most effective ways to ensure that important memories are well encoded? Even a simple sentence is easier to recall when it is meaningful. Read the following sentences, then look away and count backwards from 30 by threes to zero, and then try to write down the sentences (no peeking back at this section!).

  • The notes were sour because the seams split.
  • The voyage wasn't delayed because the bottle shattered.
  • The haystack was important because the cloth ripped.

How well did you do? By themselves, the statements that you wrote down were most likely confusing and difficult for you to recall.

Now, try writing them again, using the following prompts: bagpipe, ship christening, and parachutist. Next count backwards from 40 by fours, then check yourself to see how well you recalled the sentences this time. You can see that the sentences are now much more memorable because each of the sentences was placed in context. Material is far better encoded when you make it meaningful.

Click on the terms in the diagram below to learn more about the three types of encoding. Click the "Reset" button to clear the text and start over.

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Which of the three types of encoding do you think would give you the best memory of verbal information? We process verbal information best through semantic encoding. Words that are encoded semantically are better remembered than those encoded visually or acoustically. Semantic encoding involves a deeper level of processing than the shallower visual or acoustic encoding. Semantic encoding is even more effective if we apply what is called the self-reference effect. The self-reference effect is the tendency for an individual to have better memory for information that relates to oneself in comparison to material that has less personal relevance. Could semantic encoding be beneficial to you as you attempt to memorize the concepts in this lesson?


Once the information has been encoded, we have to somehow have to retain it. Our brains take the encoded information and place it in storage. Storage is the creation of a permanent record of information.

In order for a memory to go into storage (i.e., long-term memory), it has to pass through three distinct stages: Sensory Memory, Short-Term Memory, and finally Long-Term Memory. These stages were first proposed in 1968 in the Atkinson-Shiffrin (A-S) model of human memory (Figure 4.13), which is based on the belief that we process memories in the same way that a computer processes information.

Figure 4.13 According to the Atkinson-Shiffrin model of memory, information passes through three distinct stages in order for it to be stored in long-term memory.

But A-S is just one model of memory. Others, such as Baddeley and Hitch (1974), have proposed a model where short-term memory itself has different forms. In this model, storing memories in short-term memory is like opening different files on a computer and adding information. The type of short-term memory (or computer file) depends on the type of information received. There are memories in visual-spatial form, as well as memories of spoken or written material, and they are stored in three short-term systems: a visuospatial sketchpad, an episodic buffer, and a phonological loop. According to Baddeley and Hitch, a central executive part of memory supervises or controls the flow of information to and from the three short-term systems.

Sensory Memory

In the Atkinson-Shiffrin model, stimuli from the environment are processed first in sensory memory: storage of brief sensory events, such as sights, sounds, and tastes. It is very brief storage—up to a couple of seconds. We are constantly bombarded with sensory information, and we cannot absorb all, or even most of it. And most of it has no impact on our lives. Sensory information about sights, sounds, smells, and even textures, which we do not view as valuable information, we discard. If we view something as valuable, the information will move into our short-term memory system.

Memory Exercise

An interesting memory phenomenon called the Stroop effect indicates that you will name a color more easily if it appears printed in that color.

Try an experiment: name the colors of the words you are given in the image to the right. Do not read the words, but say the color the word is printed in. For example, upon seeing the word "yellow" in green print, you should say "green," not "yellow." This experiment is fun, but it's not as easy as it seems.

Short-Term Memory

Short-term memory (STM), sometimes called working memory, is a temporary storage system that processes incoming sensory memory. Think of short-term memory as the information you have displayed on your computer screen—a document, a spreadsheet, or a web page. Then, information in short-term memory goes to long-term memory (you save it to your hard drive), or it is discarded (you delete a document or close a web browser).

Short-term memory takes information from sensory memory and sometimes connects that memory to something already in long-term memory. Short-term memory storage lasts about 20 seconds. Research conducted in the 1950s indicated that the capacity of short-term memory was 7 plus or minus 2, though more recent research indicates that the number of items that can be retained is closer to 4. Rehearsal, the conscious repetition of information to be remembered, is required to move information from short-term memory into long-term memory, a process which is called memory consolidation.

Memory Exercise

You may find yourself asking, "How much information can our memory handle at once?" To explore the capacity and duration of your short-term memory, have a partner read the strings of random numbers out loud to you, beginning each string by saying, "Ready?" and ending each by saying, "Recall," at which point you should try to write down the string of numbers from memory.

Note the longest string at which you got the series correct. For most people, this will be close to 7, Miller's famous 7 plus or minus 2. Recall is somewhat better for random numbers than for random letters, and also often slightly better for information we hear (acoustic encoding) rather than see (visual encoding).

Long-term Memory

Long-term memory (LTM) is the continuous storage of information. Unlike short-term memory, the storage capacity of LTM has no limits. It encompasses all the things you can remember that happened more than just a few minutes ago to all of the things that you can remember that happened days, weeks, and years ago

Not all long-term memories are strong memories. Some memories can only be recalled through prompts. For example, you might easily recall a fact— "What is the capital of the United States?"—or a procedure—"How do you ride a bike?"—but you might struggle to recall the name of the restaurant where you had dinner when you were on vacation in France last summer. A prompt, such as that the restaurant was named after its owner, who spoke to you about your shared interest in soccer, may help you recall the name of the restaurant.

Long-term memory is divided into two types: explicit and implicit. Understanding the different types is important because age or particular types of brain trauma or disorders can leave certain types of LTM intact while having disastrous consequences for other types.

Click on the terms in the diagram below to learn more about explicit and implicit memory and their subtypes. Click the "Reset" button to clear the text and start over.

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Link to Learning

Clive Wearing, an accomplished musician, lost the ability to form new memories when his hippocampus was damaged through illness. Although he cannot create new memories, he can still play the piano, indicating that his procedural memory is still working. Check out the first few minutes of this documentary video for an introduction to this man and his condition.

Everyday Connection

Can You Remember Everything You Ever Did or Said?

Figure 4.14 Marilu Henner's super autobiographical memory is known as hyperthymesia. (credit: Mark Richardson)

Episodic memories are also called autobiographical memories. Let's quickly test your autobiographical memory. What were you wearing exactly five years ago today? What did you eat for lunch on April 10, 2009? You probably find it difficult, if not impossible, to answer these questions. Can you remember every event you have experienced over the course of your life—meals, conversations, clothing choices, weather conditions, and so on? Most likely none of us could even come close to answering these questions; however, American actress Marilu Henner, best known for the television show Taxi, can remember. She has an amazing and highly superior autobiographical memory (Figure 4.14).

Very few people can recall events in this way; right now, only 12 known individuals have this ability, and only a few have been studied. And although hyperthymesia normally appears in adolescence, two children in the United States appear to have memories from well before their tenth birthdays.

Watch these Part 1 and Part 2 video clips on superior autobiographical memory from the television news show 60 Minutes.


So you have worked hard to encode (via effortful processing) and store some important information for your upcoming final exam. How do you get that information back out of storage when you need it? The act of getting information out of memory storage and back into conscious awareness is known as retrieval. Our ability to retrieve information from long-term memory is vital to our everyday functioning. You must be able to retrieve information from memory in order to do everything from knowing how to brush your hair and teeth, to driving to work, to knowing how to perform your job once you get there.

There are three ways you can retrieve information out of your long-term memory storage system: recall, recognition, and relearning.

  • Recall means you can access information without cues. For example, you would use recall for an essay test.
  • Recognition happens when you identify information that you have previously learned after encountering it again. It involves a process of comparison. When you take a multiple-choice test, you are relying on recognition to help you choose the correct answer.
  • Relearning involves learning information that you previously learned. If you took Spanish in high school, but never used it, you would forget most of what you learned. However, if 10 years later you enrolled in a Spanish course, you would be surprised at how quickly you'd pick it up again.