implanting false memories. How do these memories
develop? One model of false memory development
was proposed by Giuliana Mazzoni and colleagues.
Their model contains components that are crucial to
the formation of false memories. We focus on two of
those here: the plausibility of the false event and the
belief that the event really happened.PPllaauussiibbiilliittyy
There are numerous real-life cases where
people have reported implausible—some would say
impossible—memories, ranging from being abducted
by space aliens to being forced to breed for a satanic
cult. How does the plausibility of a false event affect
the likelihood that someone might come to believe it
really happened? To answer this question, Giuliana
Mazzoni and colleagues ran a four-part experiment
over the course of several months. In the first phase,
they asked people to rate the plausibility of various
experiences, including a critical event: witnessing an
incident of demonic possession. People also reported
how likely they thought it was that they had actually
witnessed such an incident when they were very
young. At the end of this phase, the subjects reported
demonic possession as both implausible and unlikely
to have featured in their childhoods. In the second
phase, some of those people read stories about cases
of demonic possession and learned that it was a real
phenomenon. In the third phase, these same people
took a test that ostensibly measured their fears, and
their results were always interpreted to mean that they
might have witnessed a case of demonic possession.
Finally, they completed the same measures as in the
first phase. The key question was how responses at the
final phase compared with responses at the first phase.
People who had read about demonic possession and
received the fear interpretations rated witnessing it
as more plausible than they had initially. Giuliana
Mazzoni and colleagues also found that even small
changes in plausibility were enough to cause signifi-
cant changes in people’s belief that the experience had
really happened. This study and, later, related research
suggest that people can judge an event as implausible
yet harbor the belief that it had really happened. The
same is true of the relationship between plausibility
and memory; for example, the world is riddled with
adults who still remember hearing reindeer on the roof
one Christmas Eve.IInnccrreeaasseedd BBeelliieeff
The second component in the development of false
memories is the belief that the experience really hap-
pened. On this front, scientists have discovered that a
number of RMT techniques can increase belief.
One of the most common of these techniques is
imagination. What is the consequence of imagining a
false event? To answer this question, Maryanne Garry
and colleagues first asked people to report their confi-
dence that a series of childhood events had happened to
them. Later, the same people were asked to imagine
some of those events but not others and then report their
confidence again using the same test. People were more
likely to inflate their confidence for imagined events
compared with nonimagined events, an effect known as
“imagination inflation.” Other scientists have produced
imagination inflation for unusual or bizarre experi-
ences. In fact, the same kind of inflated confidence can
occur when imagination is replaced with some other
kinds of activities, such as paraphrasing statements
about fictitious events or writing a paragraph explain-
ing how the event might have happened. Still other
research shows that the act of imagination can also pro-
duce false memories, even in the absence of suggestive
“Lost in the Mall” type of descriptions. In one study,
when people imagined that they had participated in a
bogus national skin-sampling test, they became more
confident that the false procedure had occurred, and
some people developed detailed memories of it.CCoonnsseeqquueenncceess ooff FFaallssee MMeemmoorriieess
Both false beliefs and false memories can affect
behavior. In one study, people who received a false
suggestion that they had become ill after eating straw-
berry ice cream during childhood said that they would
be less likely to eat it at a party than before they
received the false suggestion. In another study, people
who imagined drinking fewer caffeinated soft drinks
later believed (and reported) having done just that.
Richard McNally and colleagues discovered that
false memories can also produce physiological signs of
distress. They found that when people who believed
that they had been abducted by aliens listened to their
own accounts of some of their most terrifying encoun-
ters with the creatures, they showed an increased heart
rate, skin electrical conductance, and muscle tension,
all symptoms that people with posttraumatic stress dis-
order show when they remember their own traumas.312 ———False MemoriesF-Cutler (Encyc)-45463.qxd 11/18/2007 12:42 PM Page 312