Cognitive Psychology: Connecting Mind, Research and Everyday Experience, 3rd Edition

Episodic and Semantic Memory (Explicit) • 159

Despite this severe impairment of memory for semantic information, she

was still able to remember events in her life. She could remember what she

had done during the day and things that had happened weeks or months

before. Thus, although she had lost semantic memories, she was still able to

form new episodic memories. Table 6.2 summarizes the two cases we have

described. These cases, taken together, demonstrate a double dissociation

between episodic and semantic memory, which supports the idea that mem-

ory for these two different types of information probably involves different

mechanisms.

Although the double dissociation shown in Table 6.2 supports the idea

of separate mechanisms for semantic and episodic memory, interpretation

of the results of studies of brain-damaged patients is often tricky because

the extent of brain damage often differs from patient to patient. In addition,

the method of testing patients may differ in different studies. It is impor-

tant, therefore, to supplement the results of neuropsychological research

with other kinds of evidence. This additional evidence is provided by brain

imaging experiments. (See Squire & Zola-Morgan, 1998, and Tulving &

Markowitsch, 1998, for further discussion of the neuropsychology of epi-

sodic and semantic memory.)

Brain Imaging Evidence Evidence for separate mechanisms has also been

provided by the results of brain imaging experiments. Brian Levine and

coworkers (2004) had participants keep diaries on audiotape describing every-

day personal events (example: “It was the last night of our Salsa dance class....

People were dancing all different styles of Salsa.... ”), and facts drawn from

their semantic knowledge (“By 1947, there were 5,000 Japanese Canadians

living in Toronto”).

When the participants later listened to these audiotaped descriptions

while in an MRI scanner, the recordings of everyday events elicited detailed

episodic autobiographical memories (people remembered their experi-

ences), while the other recordings simply reminded people of semantic facts.

● Figure 6.8 shows a cross section of the brain. The yellow areas represent

brain regions associated with episodic memories; the blue areas are brain

regions associated with semantic, factual knowledge (personal and nonper-

sonal). These results and others indicate that while there is overlap between

activation caused by episodic and semantic memories, there are major differ-

ences. Other research has also found differences between the areas activated

by episodic and semantic memory (Cabeza & Nyberg, 2000; Duzel et al.,

1999; Nyberg et al., 1996).

CONNECTIONS BETWEEN

EPISODIC AND SEMANTIC MEMORIES

The distinctions between episodic and semantic memories have been extremely useful

for understanding memory mechanisms. But although we can distinguish between epi-

sodic and semantic memory, we can also show that they are connected in various ways.

For example, when we are learning facts (potential semantic memories), we are usually

simultaneously having a personal experience, such as sitting in class or studying in the

library (a potential episodic memory, if remembered later). Here are some examples of

these connections between episodic and semantic memory.

Episodic Memories Can Be Lost, Leaving Only Semantic Memories Consider how we

acquire the knowledge that makes up our semantic memories. Sitting in the sixth grade,

you learn that the legislative branch of the U.S. government consists of the Senate and

the House of Representatives. If, a few weeks later, you remember what was going on

TABLE 6.2 Dissociations of Episodic and
Semantic Memory

Semantic Episodic

K.C. OK Poor

Italian woman Poor OK

● (^) FIGURE 6.8 Brain showing areas
activated by episodic and semantic
memories. The yellow areas represent brain
regions associated with episodic memories;
the blue areas are regions associated
with semantic memories. (Source: B. Levine
et al., “The Functional Neuroanatomy of Episodic
and Semantic Autobiographical Remembering: A
Prospective Functional MRI Study,” Journal of Cognitive
Neuroscience, 16, 1633–1646, 2004 , MIT Press Journals.)
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