5 Memory

Memory plays a key role in many areas of our lives, not the least of which is school. To understand why we remember and forget, you need to consider the entire memory process. Here’s a very simple description: First, you have to get information into your memory systems; call this process encoding. When you need to get information out of memory (for example, when you are taking an exam, or telling a story), you use the process called retrieval. In between encoding and retrieval we have, of course, memory storage.

Failure to remember information—that is, forgetting—can occur because of a breakdown at any of the three points (encoding, storage, retrieval). The typical culprits in the failure to remember, however, are encoding and retrieval problems. That’s why most of this module is devoted to encoding and retrieval. But first you need to understand the basic layout of memory, which is a key element of cognition.

This module breaks psychologists’ basic understanding of memory into five sections. First, it explains that not all forms of memory are alike and describes some of the different memory systems. The second section introduces principles of encoding and explains how recoding is one of the keys to effective memory. The third section describes the processes that take place in the brain when information is encoded and stored in memory. The fourth section covers memory retrieval. The final section describes how memories are constructed and, sometimes, distorted.

5.1 Memory Systems

5.2 Recode to Encode

5.3 Memory Storage and Memory in the Brain

5.4 Memory Retrieval

5.5 Memory Construction and Distortion

READING WITH PURPOSE

Remember and Understand

By reading and studying Module 5, you should be able to remember and describe:

• Distinctions among encoding, storage, and retrieval (5 introduction)
• Characteristics of sensory memory, working memory, and long-term memory (5.1)
• Characteristics of procedural memory and declarative memory (5.1)
• Methods of rehearsal for encoding: repetition, auditory encoding, semantic encoding (5.2)
• Strategies for semantic encoding: elaborative verbal rehearsal, self-reference (5.2)
• Organizing to encode (5.2)
• Concept map and neural networks (5.3)
• Parts of a neuron: axon, dendrites, cell body (5.3)
• Synaptic plasticity (5.3)
• Retrieval cues (5.4)
• Memory distortion (5.5)

Apply

By reading and thinking about how the concepts in Module 5 apply to real life, you should be able to:

• Identify different kinds of memory (5.1)
• Characterize your own typical study strategies in terms of encoding and retrieval principles (5.2, 5.4)
• Recognize a memory from your own life that might be distorted (5.5)

Analyze, Evaluate, and Create

By reading and thinking about Module 5, participating in classroom activities, and completing out-of-class assignments, you should be able to:

• Devise a strategy for studying that uses encoding and retrieval principles (5.2, 5.4)
• Identify a situation in which you would suspect a memory distortion (5.5)

5.1 Memory Systems

When you first start to think about it, memory might seem pretty simple.  But consider some of the memories you might have:

• What you had for breakfast this morning
• Your 10th birthday party
• The address someone just left on your voicemail
• Your phone number
• What your best friend looks like
• What a cat is
• How to read
• What you read in section 1.2 of this book
• The answer to question 3 on your History mid-term
• The name of the person you just met
• How to do a cartwheel

All of these phenomena are, at their core, memories, which means that they share some fundamental properties. Yet they have significant differences, too. It has been a major accomplishment of memory researchers to describe the different types of memory systems and processes, and determine the specific properties of each one.

Distinguishing by duration and purpose of the memory

We have two major memory systems that help to explain how memories are stored: working memory (sometimes referred to as short-term memory, although the actual meaning is not identical) and long-term memory. The process of creating a memory that you will remember for a test you will be taking next week and beyond involves both systems working together.

Soon after information is first encountered, it enters the system called working memory, simply by virtue of the fact that you pay attention to it (Baddeley and Hitch, 1974). The best way to understand working memory is to think of it as the current contents of your consciousness—that is, whatever you are thinking about right now. So as you are sitting at your desk staring at a textbook, the words that you pay attention to enter into working memory. You hold information in working memory either because you are going to use it (for example, to solve some problem) or because you will be trying to transfer, or encode it, into long-term memory.

Long-term memory is the memory system that holds information for periods of time ranging from a few minutes to many years. If you do not use or transfer the information in working memory into long-term memory, it will be forgotten, probably in less than thirty seconds (Peterson & Peterson, 1959).

One fact you should realize about working memory is that its capacity is limited. Psychologists had thought that people can generally hold about 7 pieces, or chunks, of information in working memory at one time (Miller, 1956). A chunk is a unit of meaningful information. For example, an individual letter might be a chunk. If the letters can be ordered to form words or abbreviations, then these are the chunks. More recently, however, researchers have proposed that working memory capacity is a function of time, not quantity. Specifically, our working memory may hold the amount of information that we can process in about two seconds (Baddeley, 1986, 1996).

If you manage to get the information from working memory encoded into long-term memory, it is possible that you can retain that information for many years. It can even last a lifetime; picture a 92-year-old grandmother who still tells stories about her childhood in Italy. Also, although that “I can’t study anymore because my brain is full” feeling may make you think otherwise, you can essentially store a limitless amount of information in long-term memory (Landauer, 1986).

One of the keys to good memory, then, is to have effective strategies for encoding information into long-term memory (see section 5.2). You typically store the general meaning of information in long-term memory, however, rather than precisely what you encountered (Brewer, 1977).

Working memory and long-term memory are not the only two memory storage systems. Another one is called sensory memory, and it actually comes into play before working memory does (Sperling, 1960; Crowder & Morton, 1969). Sensory memory is an extremely accurate, very short duration system. It essentially stores the information taken in by the senses, vision and hearing, just long enough (about a second) to allow you to direct attention to it so you can get the information into working memory.

Distinguishing by the kind of information in the memory

Can you do a backflip? Former World’s Strongest Man Eddie Hall can.

You can also access this video directly at: https://youtu.be/huzzUtkmZ2I

Procedural Memory

This ability to do a backflip is a skill, or a memory, like riding a bicycle, tying one’s shoes, or hitting a tennis ball. These types of memories, however, seem very different from remembering what you had for dinner last night or remembering that Albany is the capital of New York.

Psychologists, too, have noticed this distinction and have given the two kinds of memories different names. Procedural memory refers to skills and procedures. These are memories for things that you can do. Declarative memory refers to facts and episodes (Cohen & Eichenbaum, 1993). Declarative memory is further subdivided into semantic memory—your general store of knowledge, such as facts and word meanings, and episodic memory— memory for events, or episodes from your life. So, if you remember that Bismarck is the capital of North Dakota, it is semantic memory, unless you remember the exact time that you learned this fact (in 5th-grade social studies, for example), in which case it would be episodic memory. So you see, as the details about when we first learned some piece of information fade, episodic memories can become semantic memory.

Declarative Memory

Procedural memory seems to operate by different rules than declarative memory. For example, when we talk about transferring information from working memory to long-term memory (encoding) and retrieving information from long-term memory back into working memory, we are talking about declarative memory only. There is no working memory for procedures. Acquiring a procedural memory typically takes much more practice than acquiring a declarative memory does. But once a skill is acquired (that is, once it becomes part of your procedural memory), it may well be there to stay. So, at least for some people, it is probably true that you never forget how to ride a bicycle.

(See Module 9 for a related distinction called explicit and implicit memory)

5.2 Recode to Encode

Think about your best friend for a moment. What were they wearing the last time you were together? You will often find yourself unable to remember information like this. Why? Because you probably never attempted to encode that information from working memory into long-term memory. You didn’t look at your friend and say, “Lisa looks so good today; I’m going to remember what she is wearing!”

Certainly, information sometimes makes it into long-term memory without you engaging in purposeful encoding. Perhaps you have an annoying song going through your head right now. It is not very likely that when you first heard the song, you said to yourself, “Hey, I better make sure I memorize this song.” (You might be interested to know that psychologists have studied this phenomenon of annoying songs you cannot get out of your head. They call them earworms –see Jakubowski et al., 2017). But do not count on this accidental encoding to provide you with a solid memory when you need it. The simple truth is if you want to be able to retrieve information from long-term memory, you have to do a very good job of putting it in there in the first place.

How do you effectively encode information into long-term memory?

The basic strategy that people use to encode information from working memory into long-term memory is rehearsal. All of the encoding strategies in this module are kinds of rehearsal. The simplest kind of rehearsal is straight repetition. Imagine trying to learn your French vocabulary words by mentally running through the vocabulary list over and over until you get them all right. It works ok, as long as the test is soon after you finish studying (about 15 seconds seems to be the ideal delay; anything more than that and you start forgetting). Although it may be one of the most common rehearsal strategies and is the one favored by many students, repetition is probably one of the least effective. We can call this encoding without recoding. And the advice about it bears repeating: Encoding without recoding (in other words, straight repetition) is a poor way to encode information from working memory into long-term memory.

One specific situation in which many people have difficulty encoding is when they read textbooks. Have you ever read a paragraph, realized that you have immediately forgotten it, and as a consequence decided to re-read it? Often, the problem is that you are merely reading the words over in your head, making sure you can “hear” yourself silently saying the words. In this case, you are recoding: transforming the information from one form (visual) into another (auditory). But the transformation, in this case, is minor and not very useful. Psychologists call it auditory encoding or acoustic encoding. Auditory encoding is ok. Many students rely on it, and with enough effort, they do fairly well at school.

In order to remember better, however, there is no question that you should try to move to the next level of recoding, in which you transform the information into something meaningful. For example, Craik and Tulving (1975) developed the idea of semantic encoding (Craik & Tulving 1975). Semantic means “meaning,” so semantic encoding refers to mentally processing the meaning of information. For example, you should pay attention to patterns and relationships and their significance, rather than just the words or numbers themselves.

Psychologist F. I. M. Craik and his colleagues demonstrated the benefits of using semantic encoding in a famous series of experiments during the 1970s (Craik and Lockhart, 1972; Craik and Tulving, 1975). These experiments examined what Craik termed levels of processing. In a typical experiment, participants would read a list of words with instructions that would encourage one specific type of encoding. The shallowest encoding strategy (or level of processing) required participants to pay attention to the visual appearance and shapes of the letters only. For example, a shallow encoding strategy would be to count how many straight and curved letters there are in each word. Note that you do not even need to read the words in order to use this strategy, so it would seem to be quite a poor recoding strategy. Somewhat “deeper” encoding strategies were those that required participants to pay attention to more properties of the words, such as the auditory qualities. For example, judging whether the word rhymes with a specific word is a deeper encoding strategy, an acoustic one. Note that you do not need to encode the meaning of the words in order to use this strategy.

The deepest level of processing, the one that requires meaningful recoding, is semantic encoding, or paying attention to the words’ meanings. A specific task to encourage semantic encoding might be to judge whether the word makes sense in the following sentence: “The __ fell down the stairs.”

Craik’s research consistently showed that memory was better when the processing was deeper. Semantic processing was better than acoustic processing, which was better than visual processing. This is a basic principle of memory that you can start using today to improve your memory: to effectively encode, you should recode information in a way that allows you to process the meaning of what you are trying to remember.

How Can You Recode for Meaning?

One main reason that recoding for meaning helps to create solid memories is that it takes advantage of the format of information when it is stored in long-term memory. Try this: Tell a few minutes of the story “Goldilocks and the Three Bears” or any other story you know from your childhood. Did you tell the story word-for-word the way it was told to you? Probably not. But still, you remembered the characters and the sequence of events quite well. Typically (but not always), long-term memory stores information by meaning, taking advantage of patterns and creating links between concepts and people and events (Bransford et al., 1972; Brewer, 1977). This tendency allows you to recall the general story, but not the precise story, whether it is a children’s fantasy, a description in a textbook, or some event that happens to you. When you make special efforts to encode meaning, you are playing to the natural tendencies and strengths of your long-term memory.

Any way that you can make information meaningful should help make your efforts to remember more successful. Here are some useful strategies that you can use for reading textbooks and remembering lectures and other information:

Elaborative Verbal rehearsal and Self-Reference

Try elaborative verbal rehearsal, which is basically restating what you have just read or heard in your own words. After reading a short section or paragraph, pretend that a friend has asked you to explain it. Or pretend that you are trying to teach the material to someone. Although this can be difficult to do, the payoff is tremendous. In one study that compared high-performing and low-performing students who were taking General Psychology, the use of elaborative verbal rehearsal was the most important difference (Ratliff-Crain and Klopfleisch, 2005).

Use the self-reference effect by trying to apply the material to yourself (Forsyth & Wibberly, 1993; Fujita, & Horiuchi, 2004, Jackson et al., 2019). Suppose you were trying to teach some course content to someone else. You might decide to use some real-life examples to help your students understand the material. Well, it turns out that this strategy is extremely powerful for remembering the material yourself. Continually ask yourself, “Can I think of an example of this concept from my own life?” or even simply, “How does this apply to me?” Creating a mental link between the course material and what it means to you is one of the very best ways to encode meaning. With practice, you should be able to use this strategy in many of your courses. The self-reference effect is very robust; it has been demonstrated with children, college students, older adults (with and without mild cognitive impairment), and adults and adolescents with autism (Jackson et al., 2019; Lind et al., 2019).

Keep in mind as you consider trying these strategies that they can be hard to do, at least at first. It is certainly harder, and more time-consuming, to do elaborative verbal rehearsal than to simply read a textbook chapter once. But it is no more time consuming than re-reading a chapter a few times because you know you will not be able to remember it. Also keep in mind that, as you get better at using the strategies, they grow more effective and get easier to use.

Organize Information

Imagine that you are visiting a city for the first time. You have only a vague idea of where you are and you need to get to the post office. What you need is a map. A map can help you to learn where important things are and can help you figure out how to find them.

That is what the organizational aids in this book are, as well as the chapter outlines (and tables of contents) in other books and even web sitemaps. They are maps. They are useful for helping you effectively transfer information from working memory into long-term memory because they organize that information in a meaningful way.

If you can organize information meaningfully (or take advantage of a meaningful organization provided for you), it will be more effectively encoded into long-term memory (Bransford et al., 1999; Halpern, 1986). The beauty of this strategy from a practical standpoint in school is that often the work is done for you. Someone has already gone to the trouble of coming up with a meaningful organizational scheme. Use the chapter outlines to plot your route through your textbook. Pay attention during the first five minutes of the lecture when your professor gives you a preview of the day’s lecture and activities.

Signaling Meaning in Advance

One of the reasons that outlines and previews help you put information into long-term memory is that they alert you in advance to the types of information you’ll be encountering. Sometimes just a little bit of information goes a long way. Even something as simple as knowing the title of reading material before you start reading allows you to organize the information so that it makes sense and can be remembered.

John Bransford and his colleagues demonstrated this kind of effect by asking two groups of research participants to remember a paragraph. For the first group, the paragraph alone was presented. Here is one of their paragraphs. See how well you think you would remember it:

The procedure is actually quite simple. First, you arrange things into different groups. Of course, one pile may be sufficient depending on how much there is to do. If you have to go somewhere else due to lack of facilities that is the next step, otherwise you are pretty well set. It is important not to overdo things. That is, it is better to do too few things at once than too many. In the short run, this may not seem important but complications can easily arise. A mistake can be expensive as well. At first, the whole procedure will seem complicated. Soon, however, it will become just another facet of life. It is difficult to foresee any end to the necessity of this task in the immediate future, but then one never can tell. After the procedure is completed one arranges the materials into different groups again. Then they can be put into their appropriate places. Eventually, they will be used once more and the whole cycle will then have to be repeated. However, that is part of life (from Bransford and Johnson, 1972).

Do you think you would do a good job on a memory test for this paragraph? Bransford and Johnson’s participants did very poorly. Although the individual sentences are meaningful, it is difficult to see how they are related to each other—in other words, how they are organized.

The second group of participants read the same paragraph, but before doing so, they were given the title “Doing the Laundry.” Now that you know the title, go back and read the paragraph again and see if it makes sense. If you are like most of Bransford and Johnson’s participants, providing a title makes the paragraph much easier to understand and remember.

What Bransford and Johnson demonstrated is that the title allows readers to make inferences—that is, to use their background knowledge to tie the paragraph together. For example, in the second sentence, the title allows you to draw the inference that the word “things” refers to “clothes.” Inferences like these relate the formerly meaningless paragraph to the knowledge about the world that you already have. By providing a title, Bransford and Johnson allowed participants to activate their own knowledge about the way the world is organized before they started reading the paragraph. The title gave them preexisting memory hooks on which to hang the new words that they were reading.

Highlighting Relationships

In order for the technique of organizing to encode to work, you have to find the organization meaningful. That is, you have to see the organization as more than simply a list of topics. You need to learn to recognize the typical relationships between concepts. An outline or a table of contents, with items indented different amounts and different formatting for various levels of headings, also shows the relationships among the topics: which concepts can be grouped together, which are more important than others. To a very large degree, organizing information to improve encoding is simply a matter of paying attention to these types of relationships.

One very important relationship is between a general principle and an example of that principle. Look for clues in the text of your book, such as introductory phrases (“for example,” “the main idea is,” and the like). When you have identified whether a given statement is a general principle or an example, try to generate the other. If you think it is the general principle, try to come up with a new example. If you think it is an example, make sure you can identify the general principle.

Here are three other types of relationships you should make a habit of distinguishing in the materials you want to remember:

• Causes and effects. For example, if we were doing an experiment on violent video games and aggression, the independent variable, exposure to violent video games, is the supposed cause, and the dependent variable, aggressiveness, is the supposed effect (see Module 2).
• Parts and wholes. For example, a neuron is essentially a small part of the brain (the brain is made up of billions of neurons). Neurons themselves are composed of parts, including the cell body, dendrites, and axons (see the next section and Module 11).
• Levels of a hierarchy. A hierarchy is an organization system in which lower-level, or subordinate categories are included under higher-level, or superordinate categories. For example, the levels of living things that you probably learned in biology—kingdom, phylum, class, order, family, genus, species.—are organized in a hierarchy.

Any organization scheme that you come up with yourself will be particularly effective. Because you find it personally meaningful, a self-generated scheme will be easily and effectively encoded into long-term memory. You would be doing yourself a tremendous favor if you adopted a good strategy for generating these organizational schemes.

5.3 Memory Encoding and the Brain

The network of interrelated items that you have just created is a concept map. Yours might look something like this:

A concept map is, among other things, a good way to organize information for encoding into long-term memory. It signals the meanings of a number of related concepts and highlights the relationships among them (remember our discussion in section 5.2?). A concept map is also a simple representation of how networks of concepts are formed in the brain.

Creating Memories in the Brain: Activation and Synaptic Plasticity

You may already know that the brain is made up of billions of cells called neurons. For now, you can think of the brain as simply a very large collection of neurons. The neurons are all connected to each other in an extraordinarily complex pattern (one neuron can be simultaneously connected to many other neurons, all of which can be connected to many other neurons, and so on down the line). Neurons are connected to each other by axons, which look like a single long tube extending from the cell body, which is the round part of the neuron, and by dendrites, which are smaller branches splitting off from the cell body. (Each neuron has a single axon but many dendrites.) Electrical and chemical activity that takes place through pathways created by these interconnected neurons determines everything we say, think, feel, or do (see Module 11 for more details).

The neurons are involved in two significant ways when you encode information:

• Activation. When you encode information and move it into memory, many neurons throughout the brain become active. The neural activity is pulses of electricity that are caused by chemicals called ions (electrically charged particles) briefly changing locations in your brain. The ions (sodium, which is abbreviated Na+) rush into the axon of a neuron. This movement of ions produces a brief electrical charge inside the neuron, which is then transmitted to many other neurons (see Module 11 for details).
• Synaptic plasticity. In order to store information for a long time, the brain has to change its very structure—that is, the neurons themselves must change. Brain researchers currently believe that the change in structure can occur either within the individual neurons or through the connections among the billions of neurons in your brain. The connections are called synapses, hence the name synaptic plasticity. Changes that occur inside the neuron cause the neuron to produce more or fewer of the chemicals that it uses to communicate with other neurons, which are called neurotransmitters (see sec 11.3). The synapses are located at the spaces where the axon of one neuron is situated next to the dendrites of a neighboring neuron. Two things can happen in response to changing levels of neurotransmitters: the axons and dendrites can extend or retract, hence changing, ever so slightly, the structure of your brain; and the surface of the neuron can change by having more or fewer receptive areas for neurotransmitters.  Both of these events are forms of synaptic plasticity and occur whenever new information is encountered.

These two kinds of changes, especially activation, happen extremely quickly. And the changes of synaptic plasticity can last a very long time, perhaps even forever. Think about it: any time you have a new experience your brain immediately changes its electrical activity and changes its structure permanently.

Storing Memories Across the Brain: Neural Networks

So far, we have just been thinking about connections between two neurons. Let us return now to the idea that neurons are connected to each other in massive three-dimensional, dynamic, organic versions of the concept map. We call these many interconnected neurons neural networks. Many neuroscientists believe that most memories are not stored in a specific area of the brain but are spread out in interconnected neural networks across many areas of the brain. In other words, brain activation and synaptic plasticity for memories travel throughout the brain.

This neural network idea offers an explanation for why encoding meaning works so well in forming long-lasting memories. When you start searching through your brain for information—a memory—you will have a greater chance of hitting a unit of that information with a neural network that is spread out and contains a lot of information. A larger, more detailed network that uses lots of neurons will be easier to activate and use than a smaller network.

5.4 Memory Retrieval

It is the day of the big Political Science mid-term. You have been studying for days. You feel as if your head is so full of political facts, principles, and theories that it is going to explode. Your professor walks in and asks if there are any questions before they hand out the exam. “Please,” you silently beg, “hand out the exam now, before I forget everything I studied.” After ten minutes of questions from classmates (that you don’t listen to because you are too nervous), you get your exam. Question #1: How much of the U.S. government’s budget is spent on foreign aid? You know this. You just studied it last night. It is in your head somewhere if you could only find it. Why can’t you remember? You are struggling with retrieval.

Understanding (and Improving) Retrieval

Memory retrieval (withdrawing information from long-term memory for use in working memory) is largely a matter of coming up with and using effective retrieval cues. In familiar terms, retrieval cues are reminders, any information that automatically leads you to remember something. More scientifically, you can think of retrieval cues as entry points into the neural network associated with a particular memory (see sec 5.3).

You might also think of retrieval cues this (decidedly less scientific) way:  Any specific memory you have floating around in your head (the amount of U.S. foreign aid, for example) is slippery. To pull it out of long-term memory and into working memory, you need a hook, something attached to the specific memory that you can grab onto. A retrieval cue is that hook. The very best hooks are ones that you put there yourself during recoding.

To create potential retrieval cues for yourself while you’re studying, you can use the encoding/recoding principles we have already described: encode meaning and organize information. The more cues you create through this recoding and the better they are, the better your chances of being able to “grab onto one” when you need it.

Now you might begin to understand why straight repetition is only a mediocre study strategy. To be sure, the repetition of a concept and its definition provide you with a possible retrieval cue. A formerly meaningless term and definition, completely disconnected from the rest of the knowledge in your head, is not the world’s greatest hook, however.

In contrast, consider a retrieval cue that is based on memories from your own life. For example, suppose when trying to encode the concept procedural memory into your long-term memory, you remembered the time you helped your younger sibling learn how to tie their shoes. The formerly meaningless concept, procedural memory, now becomes part of your memory for this event.

Importantly, you would probably have a fairly detailed memory of such an event. Any of these details can serve you as a possible retrieval cue. Can you picture the smile on your sibling’s face when they finally got their shoes tied right? That can be your hook. Do you remember the feeling of frustration before they caught on? That can be your hook. And so on. Literally, anything you might remember about the event can work to remind you of the concept procedural memory.

That is the beauty of making the information personally meaningful (remember, it is called the self-reference effect). It becomes embedded in a rich network of information that is the easiest stuff in the world for you to remember—information about yourself. The specific hook, or retrieval cue, can be any aspect of the event that you can recall. Add this to the recoding that you did based on organization (for example, attending to the relationship between procedural and declarative memory) and by rephrasing the material in your own words, and you have an extremely powerful set of potential retrieval cues, a set of hooks that give you an excellent chance of being able to grab one when you need it.

Providing a Match Between Encoding and Retrieval

Sometimes, even extensive encoding is not enough to give you a good retrieval cue when you need it. Or, perhaps, you didn’t do a careful job of encoding. What then? Is there still a way to make retrieval cues work in your favor? Fortunately, the answer is yes.

The general strategy that you use to make retrieval cues available and useful is to try to provide some kind of match between the encoding and retrieval situations. This idea is known as the encoding specificity principle (Tulving & Thomson, 1973). If your physiological state or the external environment (the context) is similar during both encoding and retrieval, you have a better chance of coming up with a retrieval cue (Murnane & Phelps, 1993; Smith, 1979). For example, suppose you drank four cups of coffee, each with an extra shot of espresso, when you were encoding information for a big test. You might consider ingesting a bit of caffeine before retrieval time.

Even seemingly trivial aspects of the external environment, such as your location in a room, can be just the match you need to give you a retrieval cue. But hold on before you decide to wear the same clothes every day to take advantage of the encoding specificity effect.  Think about what we are saying. The encoding specificity effect allows you to remember something in a situation that closely matches the situation at encoding. That might be helpful for an exam, but is that what you really want to accomplish? For example, suppose you are studying to be a nurse. Do you really want to remember some important medical concept ONLY when you are sitting at your desk, wearing your favorite blue shirt, and chewing peppermint-flavored gum? We thought not. If you really want to learn something, to be able to retrieve it in many future situations, you would do best to simulate that when you encode it. In other words, engage in multiple encoding episodes, and vary the context in each (Bjork & Bjork 2011). This is hard. In fact, it is one of the list of strategies known as desirable difficulties. These are strategies that are difficult to use and make you feel as if you are not learning, but in reality lead to much more effective (and lasting) learning (Bjork & Bjork 2011; Smith, Glenberg & Bjork, 1978). You might also consider some of the strategies we have recommended previously (e.g., elaborative verbal rehearsal and generating self-references) to be other types of desirable difficulties. As we said previously, they can be hard to use, but they are extremely effective.

Saving the Best for Last: Retrieval Practice (and Spacing)

So, do you think that the principles we have shared so far can help you in your quest to improve your memory? (We will assume you said yes) Well, we have terrific news: We have saved some of the best news for last. There is one strategy that may have been first suggested by Aristotle and has been examined in research for over 100 years. Time and again, this strategy has been found to lead to better memory than re-studying material (Brown, Roediger, & McDermott, 2014). And very few students use this strategy (Karpicke, Butler, & Roediger, 2009). OK, have we kept you in enough suspense? Here it is: If you want to be able to retrieve information from memory, one of the most important things you should do is to PRACTICE RETRIEVING THAT INFORMATION (sorry for yelling, but this is that important). And not just once. You should practice retrieval over time, spacing out your practice sessions as much as you can. (Soderstrom et al.,2016; Karpicke and Roediger, 2008). Many students believe that it is more efficient to do all of their studying at one time, but the spacing effect shows that the very opposite is true.

This is obviously great news because you do not need to recode information or come up with new examples, or struggle with organization to use these strategies. You only need to intentionally practice and organize your time.

Just as a reminder or clarification: we are certainly not saying that you should only practice retrieval with the spacing effect. We are saying that it is the one strategy that may have the largest impact on your ability to remember. So, to summarize, allow us to present a guide to studying that is based on some of the best principles of memory that psychologists have to offer.

1. Spend some time surveying the material before you start reading it. Figure out how it is organized by reading previews and summaries, and paying attention to outlines.
2. Recode for meaning while you read: periodically pause and reflect on what you have just read. Rephrase material and come up with examples from your own life (elaborative verbal rehearsal with self-reference). Note relationships between different concepts. Pay attention to how the current information fits into what you have already learned.
3. Practice retrieving while you are reading. During some of your periodic pauses, cover up what you just read. Try to retrieve the definitions of key terms. Try to generate your elaborative verbal rehearsals without looking at the text.
4. Practice retrieval after reading. Use practice quizzes, flash cards, quizlet, etc. It is far more effective if you have to come up with the answers yourself rather than just recognizing the answer (like in a multiple-choice question).
5. Come up with a schedule that allows you to take advantage of the spacing effect.

5.5 Memory Construction and Distortion

College student Charles was always proud of their memory. In school, they rarely took notes and often had to read a chapter a single time only in order to remember it well enough to get a good grade on an exam. They also had many detailed autobiographical memories, several dating back to when they were a very small child. For example, they remembered their mother coming home from the hospital when their brother was born; they were two years, four months old. Or they remembered an early haircut, perhaps their first visit to the barber. They were sitting in the barber’s chair, eating a lollipop (covered with hair, no doubt), while their whole family stood around and watched.

One evening during Charles’s sophomore year, the family decided to watch some old family videos to celebrate their parents’ anniversary. Then, suddenly, Charles saw their memory on the television screen. It was their first haircut. Charles’s parents had obviously wanted to remember the event for the rest of their lives, so they decided to capture it on video. There in the family room, Charles saw their entire memory played out on the screen, and they realized that they did not, in fact, have a memory of their first haircut. Charles had a memory of the video of their first haircut and had mistakenly believed that it was a memory of the actual event. Charles also knew this because they had just learned this concept in their psychology class. Forgetting the actual source of a memory is very common; it is called source misattribution (Schacter, 2001). It is one form of memory distortion.

The early sections of this module emphasized how employing good encoding and retrieval skills can lead you to remember information more effectively. Somewhat hidden in those discussions, however, is an important observation about the way memory works. Although it is fair to accept the existence of different memory systems, such as working memory and long-term memory, it is not fair to assume that information gets copied into these systems perfectly, to be replayed accurately and in its entirety every time the correct retrieval cue is accessed. Memory, it turns out, is much more dynamic than that.

Instead of thinking of memory as something to be recorded and played back, it is more accurate to say you construct memories of events as you go along. The idea of memory construction might be hard to accept at first, but it is the simplest way to explain how memories for events change over time. Not only do some of the details of memories fade (as you might realize), but new details also creep into them. For example, imagine that someone tells you a very unusual story that does not make a great deal of sense to you. The story is from a non-Western culture and is quite difficult for you to follow (assuming you are from a Western culture, of course). Over time, as you attempt to recall this story, it will begin to resemble stories that are more familiar to you, with many of the cultural idiosyncrasies forgotten and replaced by themes and details more typical of Western culture (see Module 9).

A number of factors may render a memory incomplete or inaccurate. The kind and amount of processing that takes place at encoding can have a huge impact on the contents of an eventual memory. Also, minor distortions that are consistent with one’s view of the world often creep in. Imagine that you are visiting your psychology professor’s office for the first time. After leaving, you are asked to report what was in the office. Most people have beliefs about what sorts of objects would be in a professor’s office (such as desk, telephone, books), and they would be likely to think they remembered seeing these objects even if they were not actually in the professor’s office. Nearly one-third of the participants in a study similar to the situation just described reported seeing books in a professor’s office—even though the office had been specifically set up without books to test if participants would falsely remember them (Brewer & Treyens 1981).

Elizabeth Loftus and her colleagues have pioneered research on the misinformation effect, perhaps the most dramatic demonstration of the way that memory can be distorted. Loftus’s research has demonstrated that information that is given to people after an event occurs, even at retrieval, can lead to memory distortions. For example, research participants who had been shown a slide show of a car accident were later misled to believe that a stop sign was pictured in one of the slides. Many of these participants on a subsequent memory test mistakenly reported that they had seen the stop sign (Loftus et al., 1978).

In another experiment, research participants were asked one of two questions after viewing a video of an accident between two cars. In one condition, they were asked, “How fast were the cars going when they hit each other?” In the other condition, participants were asked, “How fast were the cars going when they smashed into each other?” One week later, participants who had been asked the “smashed” version of the question were more likely to report seeing broken glass in the video (Loftus et al., 1985).

The misinformation effect has been demonstrated many times, even leading participants to remember events that did not occur at all, such as spilling a punch bowl or being lost in a mall as a child (Hyman and Pentland, 1996; Loftus and Pickrell, 1995).