Chapter 2, page 38
Long-term Memory
Long-term memory (LTM) is the memory store where information is stored for very long periods
of time. But active processing does not occur in LTM. Information must be moved from LTM to working
memory to be used in active cognitive processes. Unlike working memory, which has a limited capacity,
the size of LTM has no known limits. People can store as much information in LTM as you can process
through working memory. What makes learning difficult is the limited size of working memory through
which information must pass on the way to long-term storage in LTM.
Psychologists have distinguished several kinds of knowledge in long-term memory: declarative
knowledge, procedural knowledge, metacognitive knowledge, and episodic knowledge (J. R. Anderson,
1995). Declarative knowledge is knowledge that you can express in sentence form, such as the
knowledge that rain makes things wet. You can use declarative knowledge to guide your actions and
decisions. For example, because you know that rain makes you wet, you may decide to take an umbrella
with you when it is supposed to rain.
Procedural knowledge is knowledge that specifies actions that people take. The actions can be
physical actions (the actions needed to kick a soccer ball) or mental (the mental actions needed to add two
numbers). You may or may not be able to express procedural knowledge in words. For example, if you
can ride a bicycle, you probably cannot explain all the things you do to keep your balance smoothly as you
ride, yet you carry out all these actions smoothly. Procedural knowledge is often viewed as having this
form: “If your GOAL is X, then DO y.” For instance, if your goal is to save money, then don’t go out on
weekends as often.
Metacognitive knowledge is a type of procedural knowledge that focuses on cognitive processes.
Your metacognitive knowledge is your knowledge about how to learn new information, how to solve
problems, and so on. For instance, if your goal is to get an A on a paper, you may know that you should
spend ample time writing several drafts of your paper. If your goal is to remember a long list of words,
then you should try to chunk the words in some way. We will discuss metacognitive knowledge in many
later chapters; metacognitive knowledge is the main topic of Chapter 7.
Episodic knowledge consists of memories of your own personal experiences. Your memories of
what you did with your friends in high school are an example, as are your memories of the class activities
in your educational psychology class this year.
How is information stored in LTM? One of several proposals is that information in LTM is
organized in associative networks of nodes and links between the nodes (J. R. Anderson, 1976; A. M.
Collins & Loftus, 1975). (We’ll discuss other proposals in later chapters.) Let’s return to Rachel and
consider how the information she learns about lobsters might be stored in long-term memory as an
associative network. Figure 2.6 provides an illustration. The network consists of concepts that appear in
nodes (the circles) that are connected by links (the labeled lines between the circles). Some of the concepts
and links are new ideas that Rachel learned when she read the two new sentences. Others are ideas that she
knew previously. Some of the ideas in the network are incorrect, such as Rachel’s mistaken idea that crabs
have six legs.