JOURNAL OF VERBAL LEARNING AND VERBAL BEHAVIOR 13, 585-589 (1974)
Reconstruction of Automobile Destruction:
An Example of the Interaction Between Language and Memory ~
ELIZABETHF. LOFTUS AND JOHN C. PALMER
Universityof Washington
Two experiments are reported in which subjects viewedfilms of automobile accidents
and then answered questions about events occurring in the films. The question, "About
how fast werethe cars goingwhenthey smashedinto each other?" elicitedhigherestimates
of speedthan questions whichused the verbs collided,bumped,contacted,or hit in place of
smashed. On a retest one week later, those subjects who receivedthe verb smashedwere
more likely to say "yes" to the question, "Did you see any broken glass?", even though
broken glasswas not present in the film.Theseresults are consistent with the viewthat the
questions asked subsequentto an eventcan causea reconstruction in one's memoryofthat
event.
How accurately do we remember the
details of a complex event, like a traffic
accident, that has happened in our presence ?
More specifically, how well do we do when
asked to estimate some numerical quantity
such as how long the accident took, how fast
the cars were traveling, or how much time
elapsed between the sounding of a horn and
the moment of collision?
It is well documented that most people are
markedly inaccurate in reporting such numerical
details as time, speed, and distance (Bird,
1927; Whipple, 1909). For example, most
people have difficulty estimating the duration
of an event, with some research indicating that
the tendency is to overestimate the duration of
events which are complex (Block, 1974;
Marshall, 1969; Ornstein, 1969). The judgment
of speed is especially difficult, and
practically every automobile accident results
in huge variations from one witness to another
1This research was supported by the Urban Mass
Transportation Administration,Department ofTransportation,
Grant No. WA-11-0004. Thanks go to
Geoffrey Loftus, Edward E. Smith, and Stephen
Woods for many important and helpful comments,
Reprint requestsshouldbe sentto ElizabethF. Loftus.
Department ofPsychology,UniversityofWashington,
Seattle, Washington98195.
Copyright © 1974 by Academic Press, Inc.
All rights of reproduction in any form reserved.
Printed in Great Britain
as to how fast a vehicle was actually traveling
(Gardner, 1933). In one test administered to
Air Force personnel who knew in advance
that they would be questioned about the speed
of a moving automobile, estimates ranged
from 10 to 50 mph. The car they watched was
actually going only 12 mph (Marshall, 1969,
p. 23).
Given the inaccuracies in estimates of
speed, it seems likely that there are variables
which are potentially powerful in terms of
influencing these estimates. The present
research was conducted to investigate one
such variable, namely, the phrasing of the
question used to elicit the speed judgment.
Some questions are clearly more suggestive
than others. This fact of life has resulted in
the legal concept of a leading question and in
legal rules indicating when leading questions
are allowed (Supreme Court Reporter, 1973).
A leading question is simply one that, either
by its form or content, suggests to the witness
what answer is desired or leads him to the
desired answer.
In the present study, subjects were shown
films of traffic accidents and then they
answered questions about the accident. The
subjects were interrogated about the speed of
585
586 LOFTUS AND PALMER
the vehicles in one of several ways. For
example, some subjects were asked, "About
how fast were the cars going when they hit
each other ?" while others were asked, "About
how fast were the cars going when they
smashed into each other ?" As Fillmore (1971)
and Brantford and McCarrell (in press) have
noted, hit and smashed may involve specification
of differential rates of movement.
Furthermore, the two verbs may also involve
differential specification of the likely consequences
of the events to which they are
referring. The impact of the accident is
apparently gentler for hit than for smashed.
EXPERIMENT I
Method
Forty-five students participated in groups of
various sizes. Seven films were shown, each
depicting a traffic accident. These films were
segments from longer driver's education
films borrowed from the Evergreen Safety
Council and the Seattle Police Department.
The length of the film segments ranged from
5 to 30 sec. Following each film, the subjects
received a questionnaire asking them first to,
"give an account of the accident you have just
seen," and then to answer a series of specific
questions about the accident. The critical
question was the one that interrogated the
subject about the speed of the vehicles involved
in the collision. Nine subjects were asked,
"About how fast were the cars going when they
hit each other?" Equal numbers of the
remaining subjects were interrogated with
the verbs smashed, eollided, bumped, and
contacted in place of hit. The entire experiment
lasted about an hour and a half. A different
ordering of the films was presented to each
group of subjects.
Results
Table 1 presents the mean speed estimates
for the various verbs. Following the procedures
outlined by Clark (1973), an analysis
of variance was performed with verbs as a
fixed effect, and subjects and films as random
TABLE 1
SPEED ESTIMATES FOR THE VERBS
USEDIN EXPERIMENT I
Verb Mean speedestimate
Smashed 40.8
Collided 39.3
Bumped 38.1
Hit 34.0
Contacted 31.8
effects, yielding a significant quasi F ratio,
F'(5,55) = 4.65, p < .005.
Some information about the accuracy of
subjects' estimates can be obtained from our
data. Four of the seven films were staged
crashes; the original purpose of these films
was to illustrate what can happen to human
beings when cars collide at various speeds.
One collision took place at 20 mph, one at 30,
and two at 40. The mean estimates of speed
for these four films were: 37.7, 36.2, 39.7, and
36.1 mph, respectively. In agreement with
previous work, people are not very good at
judging how fast a vehicle was actually
traveling.
Discussion
The results of this experiment indicate that
the form of a question (in this case, changes in
a single word) can markedly and systematically
affect a witness's answer to that question.
The actual speed of the vehicles controlled
little variance in subject reporting, while the
phrasing of the question controlled considerable
variance.
Two interpretations of this finding are
possible. First, it is possible that the differential
speed estimates result merely from
response-bias factors. A subject is uncertain
whether to say 30 mph or 40 mph, for example,
and the verb smashed biases his response
towards the higher estimate. A second interpretation
is that the question form causes a
change in the subject's memory representation
of the accident. The verb smashed may
change a subject's memory such that he
LANGUAGE AND MEMORY CHANGES 587
"sees" the accident as being more severe than
it actually was. If this is the case, we might
expect subjects to "remember" other details
that did not actually occur, but are commensurate
with an accident occurring at
higher speeds. The second experiment was
designed to provide additional insights into
the origin of the differential speed estimates.
EXPERIMENTII
Method
One hundred and fifty students participated
in this experiment, in groups of various sizes.
A film depicting a multiple car accident was
shown, followed by a questionnaire. The film
lasted less than 1 rain; the accident in the film
lasted 4 sec. At the end of the film, the subjects
received a questionnaire asking them first to
describe the accident in their own words, and
then to answer a series of questions about the
accident. The critical question was the one
that interrogated the subject about the speed
of the vehicles. Fifty subjects were asked,
"About how fast were the cars going when
they smashed into each other?" Fifty subjects
were asked, "About how fast were the cars
going when they hit each other?" Fifty
subjects were not interrogated about vehicular
speed.
One week later, the subjects returned and
without viewing the film again they answered
a series of questions about the accident. The
critical question here was, "Did you see any
broken glass ?" which the subjects answered
by checking "yes" or "no." This question was
embedded in a list totalling 10 questions, and
it appeared in a random position in the list.
There was no broken glass in the accident,
but, since broken glass is commensurate with
accidents occurring at high speed, we expected
that the subjects who had been asked the
smashed question might more often say "yes"
to this critical question.
Results
The mean estimate of speed for subjects
interrogated with smashed was 10.46 mph;
with hit the estimate was 8.00 mph. These
means are significantly different, t(98) = 2.00,
p < .05.
TABLE 2
DISTRIBUTION OF "YES" AND "No" RESPONSES
TO THE QUESTION, "DID YOU SEE
ANY BROKENGLASS?"
Verb condition
Response Smashed Hit Control
Yes 16 7 6
No 34 43 44
Table 2 presents the distribution of "yes"
and "no" responses for the smashed, hit, and
control subjects. An independence chi-square
test on these responses was significant beyond
the .025 level, if(2)= 7.76. The important
result in Table 2 is that the probability of
saying "yes," P(Y), to the question about
broken glass is .32 when the verb smashed is
used, and .14 with hit. Thus smashed leads
both to more "yes" responses and to higher
speed estimates. It appears to be the case that
the effect of the verb is mediated at least in
part by the speed estimate. The question now
arises: Is smashed doing anything else besides
increasing the estimate of speed? To answer
this, the function relating P(Y) to speed
estimate was calculated separately for smashed
and hit. If the speed estimate is the only way
in which effect of verb is mediated, then for a
given speed estimate, P(Y) should be independent
of verb. Table 3 shows that this is
TABLE 3
PROBABILITY OF SAYING "YEs" TO, "DID YOU SEE
ANY BROKEN GLASS.9'' CONDITIONALIZEDON SPEED
]ESTIMATES
Speed estimate (mph)
Verb
condition 1-5 6-10 11-15 16-20
Smashed .09 .27 .41 .62
Hit .06 .09 .25 .50
588 LOFTUSAND PALMER
not the case. P(Y) is lower for h# than for
smashed; the difference between the two verbs
ranges from .03 for estimates of 1-5 mph to
.18 for estimates of 6-10 mph. The average
difference between the two curves is about. 12.
Whereas the unconditional difference of .18
between the smashed and hit conditions is
attenuated, it is by no means eliminated when
estimate of speed is controlled for. It thus
appears that the verb smashedhas other effects
besides that of simply increasing the estimate
of speed. One possibility will be discussed in
the next section.
DISCUSSION
To reiterate, we have first of all provided an
additional demonstration of something that
has been known for some time, namely, that
the way a question is asked can enormously
influence the answer that is given. In this
instance, the question, "About how fast were
the cars going when they smashed into each
other ?" led to higher estimates of speed than
the same question asked with the verb
smashed replaced by hit. Furthermore, this
seemingly small change had consequences for
how questions are answered a week after the
original event occurred.
As a framework for discussing these results,
we would like to propose that two kinds of
information go into one's memory for some
complex occurrence. The first is information
gleaned during the perception of the original
event; the second is external information
supplied after the fact. Over time, information
from these two sources may be integrated in
such a way tha~ we are unable to tell from
which source some specific detail is recalled.
All we have is one "memory."
Discussing the present experiments in these
terms, we propose that the subject first forms
some representation of the accident he has
witnessed. The experimenter then, while
asking, "About how fast were the cars going
when they smashed into each other ?" supplies
a piece of external information, namely, that
the cars did indeed smash into each other.
When these two pieces of information are
integrated, the subject has a memory of an
accident that was more severe than in fact it
was. Since broken glass is commensurate
with a severe accident, the subject is more
likely to think that broken glass was present.
There is some connection between the
present work and earlier work on the influence
of verbal labels on memory for visually
presented form stimuli. A classic study in
psychology showed that when subjects are
asked to reproduce a visually presented form,
their drawings tend to err in the direction of a
more familiar object suggested by a verbal
label initially associated with the to-beremembered
form (Carmichael, Hogan, &
Walter, 1932). More recently, Daniel (1972)
showed that recognition memory, as well as
reproductive memory, was similarly affected
by verbal labels, and he concluded that the
verbal label causes a shift in the memory
strength of forms which are better representatives
of the label.
When the experimenter asks the subject,
"About how fast were the cars going when
they smashed into each other?", he is effectively
labeling the accident a smash. Extrapolating
the conclusions of Daniel to this
situation, it is natural to conclude that the
label, smash, causes a shift in the memory
representation of the accident in the direction
of being more similar to a representation suggested
by the verbal label
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