118 • CHAPTER 5 Short-Term and Working Memory
You may have wondered about questions similar
to these, as well as others that apply to your life. Any
explanation of how memory works needs to be able to
answer these kinds of questions. But what is the best way
to go about discovering how memory works? One tactic
cognitive psychologists have used is to create models like
Donald Broadbent’s fi lter model in Figure 4.3, that pro-
pose a series of processing stages to explain how people
can selectively attend to one message out of many. One
of the advantages of models is that they help organize
what we know about an area. They can also help suggest
questions to ask. For example, we saw in Chapter 4 that
attention researchers did many experiments designed to
determine how the fi lter in Broadbent’s model works.
Models have played a large role in memory research.
We begin our discussion of memory by describing a model proposed by Richard
Atkinson and Richard Shiffrin (1968). This model, shown in ● Figure 5.2, is called the
modal model of memory because it included many of the features of memory models
that were being proposed in the 1960s. This model became extremely infl uential and
shaped research on memory for many years. The stages in the model are called the
structural features of the model. There are three major structural features:- Sensory memory is an initial stage that holds all incoming information for seconds
or fractions of a second. - Short-term memory (STM) holds 5–7 items for about 15–30 seconds. We will
describe the characteristics of short-term memory in this chapter. - Long-term memory (LTM) can hold a large amount of information for years or
even decades. We will describe long-term memory in Chapters 6, 7, and 8.
Atkinson and Shiffrin also described the memory system as including control pro-
cesses, which are active processes that can be controlled by the person and may differ
from one task to another. An example of a control process is rehearsal—repeating a
stimulus over and over, as you might repeat a telephone number in order to hold it in
your mind after looking it up in the phone book or on the Internet. Other examples of
control processes are (1) strategies you might use to help make a stimulus more memo-
rable, such as relating the numbers in a phone number to a familiar date in history,
and (2) strategies of attention that help you focus on information that is particularly
important or interesting.
To illustrate how the structural features and control processes operate, let’s con-
sider what happens as Rachel looks up the number for Mineo’s Pizza on the Internet
(● Figure 5.3). When she fi rst looks at the screen, all of the information that enters her
eyes is registered in sensory memory (Figure 5.3a). Rachel uses the control process of
selective attention to focus on the number for Mineo’s, so the number enters short-term
memory (Figure 5.3b), and she uses the control process of rehearsal to keep it there
(Figure 5.3c).
Rachel knows she will want to use the number again later, so she decides that in
addition to storing the number in her cell phone, she is going to memorize the number
so it will also be stored in her mind. The process she uses to memorize the number,
which involves control processes we will discuss in Chapter 6, transfers the number into
long-term memory, where it is stored (Figure 5.3d). The process of storing the number
in long-term memory is called encoding. A few days later, when Rachel’s urge for pizza
returns, she remembers the number. This process of remembering information that is
stored in long-term memory is called retrieval (Figure 5.3e).
One thing that becomes apparent from our example is that the components of
memory do not act in isolation. Long-term memory is essential for storing information,
but before we can become aware of this stored information, it must be moved back
into STM. We will now consider each component of the model, beginning with sensory
memory.● FIGURE 5.2 Flow diagram for Atkinson and Shiff rin’s (1968)
model of memory. This model, which is described in the text, is
called the modal model because it contained features of many of
the memory models that were being proposed in the 1960s.OutputRehearsal: A control processSensory
memoryShort-
term
memoryLong-
term
memoryInputCopyright 2011 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.