Long-Term Memory
A major goal of education is to help learners store information in long-term memory and to use that information on later occasions in order to effectively solve problems. There are actually three different types (or aspects or parts) of long-term memory. Episodic memory refers to our ability to recall personal experiences from our past. When we recount events that happened during our childhood, a ballet we saw last week, or what we ate for breakfast, we are employing our long-term episodic memory. As its name suggests, this aspect of memory organizes information around episodes in our lives. When we try to recall the information, we attempt to reconstruct these episodes by picturing the events in our minds. Episodic memory enables us to recall not only events, but also information related to those events. For example, a baseball coach faced with an unusual situation requiring a rule interpretation might think like this:
"I remember a similar situation in a professional baseball game... When was it...? Last year... Reds vs. Giants... It was a night game, and the Giants had runners on first and second, when a line drive bounced and hit the umpire... What was the call...? I think they gave the batter a single and let the runners advance one base.... But I thought when the ball hit the umpire it remained in play.... Now I remember! If the umpire is in front of the fielders, it's a dead ball and a single. If the umpire would have been behind the fielder, it would have remained in play...."
Apparently, recalling memorable episodes enables us to retrieve details that would otherwise be forgotten.
Semantic memory stores facts and generalized information. It contains verbal information, concepts, rules, principles, and problem-solving skills. While episodic memory stores information as images, semantic memory stores information in networks or schemata. Information is most easily stored in semantic memory when it is meaningful - that is, easily related to existing, well-established schemata. When we retrieve information from schematic memory, we mentally follow paths like those shown in Figure 6.1. By using information on numerous occasions after it has been initially learned, we solidify the connections among elements of information, make it easier to retrieve when we need to use it, and make it more likely that this information will be available to help us accept and store additional information in the future.
Procedural memory refers to the ability to remember how to perform a task or to employ a strategy. The steps in various procedures are apparently stored in a series of steps, or stimulus-response pairings. When we retrieve information from procedural memory, we retrieve one step, which triggers the next, which triggers the next, etc.
These various parts of long-term memory do not operate in isolation from one another. While it is not clear how they work together, it is clear that they are related and overlap. For example, a teacher who is asked to write a letter of recommendation for a former student might wish to retrieve information about the ability of that student compared to other students. To do this, she might first use episodic memory to form an image of that student as a real person performing real activities in her class several years ago, and this image might help her recall specific details of class performance and term papers written by that student. Likewise, a college student writing a paper in a history course on mercantilism might first listen to or read a semantic presentation on the topic, perform an episodic memory search to recall instances in his own life when he himself experienced what the teacher was talking about, recall the semantic definitions of related terms from another course, and continue this process until he felt he could understand and integrate the new information.
There are two major problems related to the use of long-term memory: (1) to transfer the information accurately to long-term memory and (2) to retrieve the information accurately. The primary strategy for transferring information from working memory into long-term memory is referred to as encoding or elaboration. These terms refer to the process of relating information to other information that is already stored in long-term memory. Piaget and other constructivists have developed detailed theories regarding how information is stored in long-term memory, and some aspects of these schemata theories are described in Chapter 4 of this book. That information should be considered directly compatible with the information presented in this chapter.
The key ingredient that facilitates long-term storage is meaningfulness. This term refers not to the inherent interest or worthiness of information, but rather to the degree to which it can be related to information already stored in our long-term memory. One concept or piece of information is more meaningful than another if the learner can make a larger number of connections between that piece of information and other information already in long-term memory.
Since meaningfulness is a critical factor in storing information, one of the most important strategies for promoting long-term storage and retrieval of information is to have the student learn it in a meaningful context. Since meaningfulness refers to the number of connections between new and old information, one of the best ways to promote meaningfulness is for the learner to have an abundance of information related to a topic already well organized in long-term memory. To take a simple example, a person with ten pieces of information in long-term memory related to a topic will have a better chance of treating the topic meaningfully than will a person with only one related piece of information stored in memory. In other words, this is another case of "the rich getting richer." For example, a student who has recently viewed West Side Story, who has a friend who has been recently involved in a romantic attachment against the objections of his parents, who has already read three other Shakespearean tragedies, and who has a rich vocabulary will find it much easier to understand and retrieve information about Romeo and Juliet than an equally intelligent peer with no background knowledge related to the play.
The preceding paragraph demonstrates the value of being familiar with the important terms and concepts within a society's dominant culture. Hirsch (1987) has shown that a student's level of cultural literacy is strongly related to success in school; that is, students who are familiar with more of the concepts emphasized within a culture can learn more easily within that culture than students familiar with fewer concepts. This is one application of meaningfulness to learning. Another valid insight is that learners may have numerous ideas that are in fact related to a topic but may need help seeing and making the connections. For example, a student reading Romeo and Juliet who knows little about Shakespeare or any of his plays may still find it to be extremely meaningful if the teacher points out connections to contemporary movies, songs, popular novels, and rock videos with which the student is already familiar.
Possessing information related to a topic will not help students learn and retain new information unless they activate this information and bring it to bear on the topic at hand. Advance organizers help accomplish this task. An advance organizer is an introductory statement about a topic that supplies a structure for the new information and relates it to information already in long-term memory. For example, while introducing a unit on the Civil War, a teacher might say, "Remember that we have found that wars usually occur because of a combination of political and economic factors...." Likewise, when teaching adult students how to use an electronic database management program, a teacher might say, "An electronic database is very much like a system of index cards...." or "A telephone directory is one type of non-electronic database. Imagine that the phone directory could easily be searched by either name, phone number, or address...." These introductory comments enable the learners to activate information that may not otherwise be available during the learning process and therefore to make connections that they would not have been likely to make had they not received the prior advice to activate this information.
An effective alternative to the advance organizer is the orienting question (Andre & Thieman, 1988; Moorman & Blanton, 1990). In this case, the teacher (or textbook writer) asks questions to stimulate the learner to think about information that is likely to be helpful in understanding and organizing the information the learner will encounter. To be effective, the stimulus to generate prior, related knowledge has to be perceived as worthwhile by the learner (Osman & Hannafin, 1994).
The question or other stimulus does not necessarily have to come before the learner encounters the new information. For example, a strategy called elaborative interrogation requires learners to give explanations or to in some other way expand upon the information they have been examining (Pressley, Symons, McDaniel, Snyder, and Turnure, 1988; Martin & Pressley, 1991). For example, I could first explain elaborative interrogation to you and then ask you, "Why do you suppose it works?" If you would invent an answer of your own, you would be more likely to remember what this concept is than if I simply gave you the answer. Why do you suppose this is the case? (Note: In case you missed it, the preceding sentence was an example of elaborative interrogation. It works only if you take the time to answer the question.)
Note that advance organizers and orienting questions are useful in any learning situation - not just for lectures or for reading textbooks. Ideally, learners should learn to ask their own questions or search their own minds for related knowledge, even when they are engaged in learning activities that are otherwise highly unstructured. This process of encouraging students to activate their own prior knowledge will be covered in greater detail in chapter 7 in the discussion of metacognitive skills, self-monitoring, and scaffolded instruction.
Analogies often serve as informal but effective advance organizers. Sometimes the analogy is conveyed very informally. For example, simply telling students that what they are looking at is a pie graph may be enough to activate in the minds of young math students what they already know about dividing pies and to apply this to interpreting pie graphs. In other cases, the teacher will find it useful to present the analogy more systematically. Box 6.4 later in this chapter is an example of using computer technology as an analogy to understand human thinking. If you know absolutely nothing about computer technology, that analogy will not help you understand human thought processes. If you do understand computer technology, that analogy may help you better understand this chapter. Analogical thinking is discussed in greater detail in chapter 7.
Diagrams and models offer another way to help learners to organize information and relate it to existing information. Since diagrams and models often serve this useful purpose, it is often useful to help learners interact with them. For example, at the beginning of this chapter, Figure 6.1 presented a model of information processing. The Short Quiz presented immediately adjacent to that model was designed to force you to look at the diagram closely and to use it as a basis for organizing and eventually retrieving information regarding this topic. When questions like these are not available in textbooks, it is often a good strategy for teachers or students themselves to ask and answer questions about such diagrams. It is also very useful for students to diagram information themselves, in order to see the relationships more clearly and thereby transfer the information more adequately to long-term memory. Outlining the key concepts of a unit of instruction can provide similar benefits.
As chapter 3 showed, sometimes students learn during "feedback loops." For example, a student who misses an item on a quiz may examine the question closely and selectively focus for the first time on the correct information. {That is, he uses his selective perception correctly.} This correct focus {which never would have occurred had the student never made the mistake} enables the learner to think the information over correctly and integrate it correctly with what he already knows. {That is, he is able to encode it for future retrieval in his long-term memory.}
The strategies for encoding information in long-term memory described in the preceding paragraphs can be generally classified as elaboration. Students elaborate on material by connecting it to material already in their own minds. Any technique that enables the learner to connect current information to existing information is likely to increase its meaningfulness and hence the ease with which it can be transferred to and later recalled from long-term memory. Everyone involved in the instructional process - teacher, student, textbook writer - can facilitate the recall of information and its availability for use in problem solving by enabling learners to make information more meaningful - that is, to act upon the information in such a way as to see connections between what the learner is learning and what is already in the learner's mind.
Most college textbooks (including this one) have summaries at the end of each chapter. Do these summaries help readers learn and later recall the information? Actually, many readers skip the summaries, because they "have already learned that information." However, if these summaries are well written and properly employed by readers, they can serve as a basis for ascertaining that the information has been fully understood and properly related to other material. For these benefits to occur, the readers must actively look for connections between what the summary says and what is available in their long-term memories.
Many college students underline or highlight key concepts while reading their textbooks. Does underlining stimulate effective learning and subsequent recall of information? The answer seems to be that underlining works if it is done properly - otherwise, it may actually inhibit learning. The right way is to underline very few sentences and ideas. The wrong way is to underline so many sentences and ideas that the pen or marker is really serving as a pointing device. By underlining a smaller amount of information, the learner is forced to actively process the ideas while selecting those most worthy of being underlined. It is this active processing that increases the meaningfulness of the text.
What to Do To Help the Learner Transfer the Information Accurately from Working Memory to Long-Term Memory.
- Treat the information actively rather than passively. Interact with the information in meaningful ways: ask yourself questions about it, have the learner diagram it, outline it, etc.
- Look for relationships between the new information and other information that is already in long-term memory.
- Look for differences between the new information and other information that is already in long-term memory.
- Use mnemonic strategies.
The key point of this section is that information is stored in the long-term memory in a structured fashion - with elements of knowledge chained together or organized in schemata related to specific topics. Information is likely to be effectively entered into long-term memory (and available for subsequent retrieval) to the extent that the learner actively interacts with the information in working memory. It is impossible to actively interact with information without making connections with existing information, and these connections facilitate storage of information - even if the learner is unaware that information is being transferred to long-term memory. A large amount of permanent learning occurs automatically, without conscious effort on the part of the learner. In other instances, the learner may make deliberate attempts to transfer information to long-term memory, as by using the mnemonic strategies described later in this chapter, or by using the metacognitive strategies described in the next chapter.
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