162 • CHAPTER 6 Long-Term Memory: Structure
task, in which the participant’s task is to create a word from a fragment. For example, the
priming stimulus could be the word parrot, and the test stimulus could be the fragment par.
The participant’s task is to add letters to create a word. If repetition priming occurs, the par-
ticipant will be more likely to complete the fragment to form the priming stimulus then he
or she would be if the stimulus had not been presented earlier. In this example, creating the
word parrot, rather than other possibilities such as parent or party, would illustrate an eff ect
of priming.
Another example of a test used in repetition priming experiments involves measuring how
accurately or quickly the participant responds to a stimulus. For example, participants could
be tested by presenting a list of words and asking them to press a key every time they see a
word that has four letters. Priming would be indicated by faster or more accurate responding
to four-letter words that corresponded to priming stimuli that had been presented earlier. The
key characteristic of this test is speed. Requiring a rapid response decreases the chances that
the participant will take the time to consciously recollect whether or not they have previously
seen the word.Many experiments have been done in which researchers have demonstrated implicit
memory using techniques like the ones described above (Roediger, 1990). But the defi -
nite proof that priming involves implicit memory is provided by neuropsychology
experiments on people with amnesia like Jimmy G., whom we described at the begin-
ning of the chapter, who cannot remember events that have just happened to them.
An example is provided by an experiment by Peter Graf and coworkers (1985),
who tested three groups of participants: (1) eight amnesia patients with Korsakoff’s
syndrome and two patients with another form of amnesia; (2) patients without amnesia
who were under treatment for alcoholism; and (3) patients without amnesia who had
no history of alcoholism.
Graf and coworkers presented lists of words to their participants and asked them to
rate each word on a scale of 1 to 5 based on how much they liked each word (1 = like
extremely; 5 = dislike extremely). This caused partici-
pants to focus on rating the words rather than on com-
mitting the words to memory. Immediately after rating
the words in the lists, participants were tested in one of
two ways: (1) a test of explicit memory, in which they
were asked to recall the words they had seen; or (2) a
test of implicit memory, in which they were presented
with three-letter fragments and were asked to add a few
letters to create the fi rst word that came into their mind.
The results of the recall experiment, shown in
● Figure 6.10a, show that the amnesia patients had
poor recall compared to the two control groups. This
poor recall confi rms the poor explicit memory associ-
ated with their amnesia. But the result of the implicit
memory test, in Figure 6.10b, tells a different story.
These results, which indicate the percentage of primed
words that were created in the word completion test,
demonstrates that the amnesia patient performed just as
well as the controls. This shows that priming can occur
even when there is little explicit memory for the words.
Another example of repetition priming in a person
with brain damage is an experi ment in which Elizabeth
Warrington and Lawrence Weiskrantz (1968) tested
fi ve patients with Korsakoff’s syndrome. The research-
ers presented incomplete pictures, such as the ones in
● Figure 6.11 (Gollin, 1960), and the participant’s task
was to identify the picture. The fragmented version in● (^) FIGURE 6.10 Results of the Graf et al. (1985) experiment. (a) The
results of the recall test indicate that the amnesic patients (AMN)
did poorly on the test compared to the medical inpatients (INPT)
and the alcoholic controls (ALC). (b) The results of the implicit
memory test, in which the task was to complete three-letter word
stems, shows that the amnesic patients performed as well as the
other patients. (Source: P. Graf, A. P. Shimamura, & L. R. Squire, “Priming Across
Modalities and Priming Across Category Levels: Extending the Domain of Preserved
Function in Amnesia,” Journal of Experimental Psychology: Learning, Memory, and
Cognition, 11, 386–396, 1985.)
INPT ALC AMN
50
40
30
20
10
0
Percent words recalled
Recall Implicit memory test
(a)
INPT ALC AMN
50
40
30
20
10
0
Percent words completed
(b)
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