156 • CHAPTER 6 Long-Term Memory: Structure
Brain Imaging Some brain imaging experiments have demonstrated activation
of different areas of the brain for STM and LTM. For example, Deborah Talmi and
coworkers (2005) measured the fMRI response to tasks involving STM and LTM. They
fi rst presented a list of words to participants, as is done to determine a serial position
curve. But instead of asking participants to recall the words, they presented a single
“probe” word. The probe was either (1) a word from near the beginning of the list, (2)
a word from near the end of the list, or (3) a new word that hadn’t been presented ear-
lier. The participants’ task was to indicate whether the word had been presented before.
Their brain activity was measured with fMRI after the probe was presented and as they
were preparing to respond.
The results indicated that probe words that were from the beginning of the
list (which, if remembered, would therefore represent long-term memory) acti-
vated areas of the brain associated with both long-term memory and short-term
memory. It would be expected that both areas would be activated because words
at the beginning of the list would be in long-term memory (primacy effect, see
page 151) and would then be transferred into STM when they were being recalled.
In contrast, probe words from the end of the list only activated areas of the brain
associated with short-term memory. This would be expected because the recently
presented words would be recalled directly from short-term memory (recency
effect, see page 153).
Although Talmi’s experiment demonstrated activation of different areas for
STM and LTM, the results of other brain imaging experiments have not been as
clear-cut. Some of these experiments have shown that tasks that involve either
STM or LTM can activate the same areas of the brain (Jonides et al., 2008). One
possible reason for this overlap is the constant interplay that occurs between STM
and LTM. Another reason is that STM and LTM may share some of the same
mechanisms.TYPES OF LONG-TERM MEMORY
There are a number of different types of long-term memory. ● Figure 6.6 indicates
that the two main divisions of LTM are explicit memory and implicit memory.
Explicit memory (also called conscious memory or declarative memory), on the
left of the figure, consists of episodic memory, memory for personal experiences,
and semantic memory, stored knowledge and memory for facts. Episodic and
semantic memories are illustrated by two memories that Cliff, the student shown
in ● Figure 6.7, is experiencing. When he remembers talking with Gail yesterday
about meeting to study for the cognitive psychology exam, he is having an episodic
memory. When he remembers some facts about theories of attention that he learned
in his cognitive psychology class, he is having
a semantic memory. Both of these types of
memory are called explicit, because their con-
tents can be described or reported (Smith &
Grossman, 2008).
The other division of long-term memory,
implicit memory, is shown at the right of
● Figure 6.6. Implicit memories (also called non-
declarative memory or unconscious memory)
are memories that are used without awareness,
so the contents of implicit memories cannot be
reported (Smith & Grossman, 2008). One type
of implicit memories that has infl uenced Cliff’s
behavior is priming—a change in response to a
stimulus caused by the previous presentation of
the same or a similar stimulus. An example of
priming would be fi nding it easier to recognize● (^) FIGURE 6.6 Long-term memory can be divided into explicit memory
and implicit memory. We can also distinguish between two types of explicit
memory, episodic and semantic. There are a number of diff erent types of
implicit memory. Three of the main types are priming, procedural memory,
and conditioning.
LONG-TERM MEMORY
EXPLICIT
(conscious)
Semantic
(facts,
knowledge)
Procedural
memory
Episodic Conditioning
(personal
events)
IMPLICIT
(not conscious)
Priming
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