In the previous chapter we considered the process of encoding, emphasizing that it is not accurate to characterize it as the intentional act of learning; rather, it is how experience becomes memory, depending on certain features of our thought at the time. In this chapter, we describe retrieval, the process of bringing a long-term memory back to consciousness. We consider what makes successful retrieval possible and also what might make it unreliable. In many situations, we know we have experienced something (we had a chance to encode it), but when we later have reason to retrieve it, we cannot access the memory.

You may have taken this class thinking, “Oh, boy, now I’ll learn how thinking works and how I can think better. Look out world!” You expected to read about controlling mind wandering, evaluating information, and making good choices. If so, you were understandably perplexed that we’ve spent twelve chapters on topics, such as perception and short-term memory, that you hadn’t thought of as “thinking.” We’ve offered little help to the hopeful super-thinker, and you’ve been a good sport about that. Here, toward the end of the book, we’re going to come through for you. However, as by now you will have guessed, our study of “thinking” will still confound your initial expectations because unconscious processes will loom large.

We began the last chapter by defining attention as continued cognitive processing or continued thought. For the next few chapters, we follow that continued thought in the form of memory. We usually think of “memory” as something we’re aware of, as when you remember which friend is allergic to shellfish or where you parked your car. But we’re going to expand what we think of as memory by imagining a few cases where the time between the event and the memory of the event is so short that we use it without realizing it.

Human language is a magnificently complex cognitive process, integrating many of the processes we’ve already discussed. You must accurately perceive the letters or the sounds. You must link them to the intended memory representations of what those letters or sounds correspond to. Then you must make sense of the piece of language as a whole, in the context of a rich network of memories. Think of what goes unstated in the earlier joke. You must choose a meaning for “cutting” that is not about knives or standing in line but about insults. You must understand that a “clown” is not just a positive role of someone who entertains at children’s birthday parties and is a talented physical comedian in circuses but also someone who is rude or stupid. Finally, you have to see the humor in calling someone rude or stupid, but not so rude and stupid that they become famous for it.

In Chapter 1, we discussed the objections the behaviorists raised to the cognitive program. One of their concerns was the use of nonobservables in theory, for example, creating a theory of how memory works that includes representations such as short-term and long-term memory. No one can actually see or otherwise directly observe short-term memory, so how can we use it to explain human behavior? Cognitivists replied that they were going to use human behavior to test their models. But if so, it seems inevitable that their reasoning would end up being circular. They want to explain how humans behave, yet they plan to test whether the model is right using that same behavior.

In the previous chapter we considered the structure of our memories. What are the different kinds of memories? How are they organized? In this chapter and the next we will focus on the processes that turn experiences into memories and help us recall these memories later. Each chapter describes one of the two basic processes of memory: encoding and retrieval.

While our working memory system maintains information for short periods of time – seconds or minutes – we also need to maintain information over much longer periods: hours, days, weeks, months, and even years. Researchers call this long-term memory. Most questions people have about their own long-term memories are prompted when there’s a failure. Why can’t I remember that person’s name? Where did I put my glasses? What’s the answer to number 7 on this quiz? Cognitive psychologists are interested in failures of memory but more broadly target memory organization (its structure) and memory operation (its processes). Of course, the hope is that once we figure these things out, we can answer more specific and individual questions like where your glasses are (have you checked your head?) or how to study effectively (have you tested yourself?). In this chapter we will first describe the structure of long-term memory: We’ll describe different types of long-term memory and their organization. In the next two chapters, we will describe memory processes of encoding (getting memory in) and retrieval (bringing memory back for current use).

A problem can be defined very generally as any situation in which a person has a goal that is not yet accomplished. That definition encompasses what we called decision-making. When psychologists talk about problem-solving, however, they typically mean open-ended problems in which the person knows the goal but nothing in the problem describes how to accomplish the goal.

In Chapter 6 we asked how explicit memory was organized (e.g., how does the concept for “bird” relate to the concept for “robin”), but we only briefly addressed the concepts themselves. This chapter focuses on how we represent categories in the real world by forming mental concepts. As we learn about the world, how do we decide which items belong in the same category? This chapter explores how we draw the lines that define categories and how we use mental representations to do other kinds of thinking.

In the last chapter we discussed the structure of language and introduced four levels of analysis. In this chapter we discuss how the process of language comprehension solves problems and resolves ambiguities. We’ll first describe these problems by asking, What makes language processing difficult?

When you are driving and your mind wanders from the song on the radio to the next left turn to what’s for dinner, do you pause in the middle to wonder what makes your mind wander? Probably not. Many people only contemplate how the mind works when their minds let them down. They contemplate memory (“Why can’t I remember the answer to this test question?”), attention (“I want to understand this material, so why can’t I keep my focus on my book and not on my phone?”), and vision (“How could someone think those two colors go well together?”). Questions such as “How does vision work?” seem somewhat interesting, but no more interesting than thousands of other questions about how the world works (How do viruses work? How do cell phones work? How do your lungs work?). These questions become interesting to most people when they consider how the answers might help their own lives.

Of all the cognitive functions your brain performs, vision is both the most remarkable and the most difficult to appreciate. It is difficult to appreciate vision precisely because it is so marvelous; your visual system works so efficiently, so effortlessly, that you have no clue what it is doing or how difficult its task is. Consider this: For decades we’ve had calculators that can perform long division far more quickly and accurately than any human. We also have computer programs that can beat 99 percent of the population in chess. Now, after years of work and millions of dollars spent, we are finally beginning to have computers that are able to recognize faces and drive a car.