the effect of postevent information is that the mislead-
ing postevent information simply substitutes informa-
tion in memory when there is no accessible memory
for the relevant details of the original event. In fact,
even when we pay attention, we do not remember
everything about an event that we observe. According
to this interpretation, only if individuals cannot
remember seeing a stop signare they likely to incor-
porate the suggested yield sign.
This latter interpretation, referred to as thetrace
strength theory of suggestibility, has important impli-
cations for some of the constraints on the effect of
postevent information. Although memory is a con-
structive process, and we can incorporate postevent
information into our memory for what we observe, in
fact our memory is generally quite accurate. What is
the vehicle by which the veracity of memory is pre-
served? It is now clear from a number of research
studies that stronger memories are more likely to resist
suggestion than weaker memories; we are less likely to
be misled about details of events if we saw them very
clearly to begin with and remember them well than if
we did not remember them well. Kathy Pezdek con-
ducted a research study in which children were pre-
sented a sequence of slides depicting an event. The
target slides that were presented once or twice each
were included in the sequence. A postevent narrative
was then read that described the same event; in the nar-
rative were several misleading sentences that sug-
gested a change in what had been observed in the
slides. The children were significantly less likely to be
misled by the postevent narrative if they had observed
the target slides twice rather than once; the stronger
memory was more resistant to suggestibility. This con-
clusion is also supported by the results of other studies
in which it has been reported that children are less sug-
gestible in domains in which they have greater knowl-
edge (i.e., greater memory strength).Can Postevent Information Plant
False Events in Memory?
Research on the influence of postevent information is
often used to imply that it is relatively easy to sugges-
tively mislead a person to believe that an entirely new
event had occurred when it had not. This assumption
is at the heart of the false-memory debate. This debate
concerns the veracity of delayed memory for incidents
of childhood sexual abuse. Analyses by Jennifer Freyd
and her colleagues have established the pervasiveness
of childhood sexual abuse. Nonetheless, some claimsof childhood sexual abuse might be based on “false
memories”; that is, the abuse never occurred, but
memory of the abuse was planted by postevent infor-
mation, such as suggestive questioning by overzeal-
ous police officers, social workers, or therapists who
interviewed the child.
According to the trace strength theory of sug-
gestibility, if a child is recalling an event that was
experienced several times, he or she would be expected
to have a more accurate memory of the event and be
less vulnerable to suggestive influences such as biased
interviewing procedures than if the event had occurred
only once. This is especially important in child abuse
cases because it is common for a perpetrator to fre-
quently abuse the same child. A child’s memory for an
incident that occurred frequently would be expected to
be relatively reliable, even in the face of possibly sug-
gestive interviewing.
Another important constraint on the effect of
postevent suggestion is that implausible events are less
likely to be suggestively planted in memory than plau-
sible events. In one study on this point, Kathy Pezdek
and her colleagues had 20 confederates read descrip-
tions of one true event and two false events to a
younger sibling or close relative. The more plausible
false event described the relative being lost in a mall
while shopping; the less plausible false event described
the relative receiving an enema. Three events were
falsely remembered: all were the more plausible
events. Thus, all memories are not equally likely to be
suggestively planted in memory, and individuals with
differing prior experience and prior knowledge are not
equally vulnerable to suggestion. The relative ease of
suggestively planting false childhood memories of
sexual abuse versus being lost in a mall while shopping
should be related to the relative plausibility of these
two events to a particular individual. This research
demonstrates that although memory can be influenced
by postevent information, there are constraints on the
conditions under which this is likely to occur.Kathy PezdekSee alsoDelusions; Eyewitness Memory; False Confessions;
False MemoriesFurther Readings
Freyd, J. J., Putnam, F. W., Lyon, T. D., Becher-Blease,
K. A., Cheit, R. E., Siegel, N. B., et al. (2005). The
science of child sexual abuse. Science, 308,501.Postevent Information and Eyewitness Memory——— 609P-Cutler (Encyc)-45463.qxd 11/18/2007 12:43 PM Page 609