have said in previous accounts, while truth - tellers will attempt to reconstruct
Truthfulness in Witnesses’ and Suspects’ Reports
291
an event they actually experienced. Because deceptive suspects possess the
common - sense understanding that fewer details are easier to remember than
multiple details, they will make their statements as short as possible in order
to avoid contradictions and inconsistencies over repeated interviews. Thus, our
fi rst hypothesis was that deceptive suspects would give shorter statements and
omit more details than truthful suspects across repeated interviews.
The second major interest of this research was the investigation of the
impact of deception on recall time and duration estimates, a focus of interest
that has yet to be empirically explored by researchers. An individual ’ s ability
to provide an accurate account of both where he or she was and the times or
durations of these events has practical forensic implications (Loftus, et al .,
1987 ; Jackson, Michon & Melchior, 1993 ; Yarmey, 2000 ; Pedersen & Wright,
2002 ). If a suspect provides alibi evidence of a timeframe of a critical event
that overestimates or underestimates the actual duration or confl icts with evi-
dence from witnesses ’ duration estimates of the same event, police can use the
temporal statement as an investigative tool. Theoretical and empirical investi-
gation of duration estimations date back to the nineteenth century, with
Vierordt ’ s (1868) discovery that short intervals tend to be overestimated and
longer ones underestimated. Consistent with Vierordt
’ s Law, forensically
related research has shown that witnesses tend on average to overestimate the
duration of relatively short events lasting a few minutes or less (e.g., Loftus
et al ., 1987 ; Yarmey & Yarmey, 1997 ) and underestimate relatively long events
lasting 20 minutes and more (Yarmey, 1990 ).
People perceive and recall the duration of events subjectively and their
estimations of time are infl uenced by cognitive, affective and subjective prefer-
ence (Carmichael, 1997 ). Deceptive suspects have different purposes, goals
and agendas from truthful suspects. That is, deceptive suspects probably wish
to distort their time reports and distance themselves from the period in which
the crime occurred. Deceptive participants in this study were told to be cred-
ible in their reports. As a consequence they would probably make duration
estimations constrained somewhat by reality rather than construct fantasy - type
fabrications (Johnson & Raye, 1981 ; Johnson & Sherman, 1990 ). Whereas
the research literature would support the prediction that truthful participants
would overestimate the duration of their involvement in short - term, mundane
activities (see Yarmey,
2000 ), it was uncertain whether deceptive suspects
would overestimate or underestimate the duration of both routine activities
and the critical incident. It also was uncertain whether deceptive participants
would differ from truthful participants in estimating the specifi c time in which
the critical incident began.
Research p articipants and p rocedures
Nineteen men and women were randomly assigned to a truthful condition and
17 to a deceptive condition (overall
M age
= 27.61 years,
SD = 10.34).
All participants (14 men and 22 women) were city - dwellers and worked in
292
Handbook of Psychology of Investigative Interviewing
different occupations (business, homemakers, educators, college students, and
so forth). The experiment used a 2 (Group: Deceptive, Truthful) × 3 (Repeated
interviews: one - day, one - week, two - week retention interval) mixed - group fac-
torial design.
Two female psychology students acted as both observers and as mock police
offi cers for the experiment. The observer accompanied the participant for a
two - hour period during which time notes were taken of each change in an
event or activity. Observations were done outside of normal working hours,
but the participant was free to do any type of activity. Common activities
included eating, household chores, and so forth. The observer did not interact
with the participant during this period, except to announce that they were
‘ going for a walk
’ . The procedure involved taking on
- the - spot records of
behaviour as it occurred for two continuous hours. This record was then
compared to the participant ’ s later report of his or her activities in an attempt
to establish the accuracy or distortion of time - delayed recall. The observer
recorded all activities initiated by the participant and the amount of time
engaged in each activity in chronological order. Timing of activities was
rounded off and recorded to the nearest minute. The level of detail for an
activity unit was to be such that someone reading the description could visual-
ize the events as they occurred. An activity unit of behaviour was defi ned as a
natural and meaningful action with a start and ending and which lasted
approximately one minute or longer in duration.
Approximately 40 minutes into the observation session the observer
announced that they were leaving the residence (assuming they were indoors
at this time) and going for walk. Once outside the observer placed an envelope
on the ground as if someone had dropped it. The participant had earlier
been instructed to pick up the envelope, read its contents and then put the
‘ found ’ materials in their pocket or purse. Participants in the truthful condi-
tion found an envelope containing a one - page advertisement fl yer. This was
accompanied by a note stating that the participant was to read the ad for
information purposes only, but was not expected to memorize it. Participants
in the deceptive condition picked up an envelope containing a bank note
worth $25,000 payable on demand to the bearer. An accompanying note
informed the participant that ‘ although the money does not belong to you,
you will keep it rather than trying to locate its owner or hand it over to the
police. From this point on you realize that you must protect yourself. No
one, particularly the police, should know that you have kept the money. When
you are questioned about the lost note you will be trying to fool the inter-
viewer (a mock police offi cer) but will try to be credible and convincing in
your reports ’ .
After ‘ fi nding ’ the lost materials all participants were instructed to carry on
their activities as they saw fi t during the rest of the observation period.
Participants also were told that the observer and mock police offi cer did not
know which group they were in and they were not to reveal this information.
The participants were interviewed one day, one week and two weeks later. The
Truthfulness in Witnesses’ and Suspects’ Reports
293
mock police offi cer told the participants that a witness had reported that they
in the general vicinity of where the envelopes were lost and that the police
wanted them to answer a few questions about their whereabout
s at the approx-
imate time of the incident. The participants were asked to put in writing all
the activities they could recall engaging in during the two - hour observation
period and the amount of time spent performing each one, or the time it
started and stopped. They were told to recall those types of activities lasting
approximately one minute or longer, or any activity they considered to be
distinct or important, regardless of its duration. In order to allow participants
to determine their own order of free recall, they were told that the chronologi-
cal order of their recall was not important. When participants fi nished their
report they were asked if they remembered being told by the observer: ‘ We
are going for a walk ’ . If the participants said ‘ yes ’ , they were asked to estimate
the specifi c time of day that occurred.
Results and d iscussion
To summarize our fi ndings, the analyses of free recall scores showed that, in
contrast to truthful suspects, the reports of deceptive suspects declined sig-
nifi cantly from the initial interview compared to one and two weeks later.
Signifi cant differences were found for: the total number of activities reported
regardless of accuracy; the percentage correspondence of activities scores
(that is, the agreement between the number of correct activities observed by
the research assistant and reported by the participant converted into ratio
scores); and the level of precision of details reported. Contrary to our expecta-
tions, truthful suspects did not show an increase in the amount of correct
information reported across interviews (hypermnesia) or new information
recalled across interviews (reminiscence effects). Furthermore, no signifi cant
difference was found between truth
- tellers and deceptive suspects in the
chronological structure of their free narrations of the two - hour observation
period.
No signifi cant differences were found between truthful suspects and decep-
tive suspects in their duration estimations for seven categories entailing routine
mundane activities. However, on the critical event involving a walk, a signifi -
cant difference in duration estimations was obtained. Whereas truthful suspects
on average overestimated this short - duration event, deceptive suspects were
highly consistent in signifi cantly underestimating the duration of the critical
event. These differences occurred in spite of the fact that no signifi cant differ-
ences were found between the two groups in their estimation of the time when
the walk event began.
In line with our interpretation of Granhag & Str ö mwall ’ s (2000) ‘ repeat
vs. reconstruct
’ hypothesis, this experiment showed that the number and
percentage accuracy of activities and the number of details reported by
deceptive suspects decreased across interviews. In order to remember what was
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Handbook of Psychology of Investigative Interviewing
previously said, a deceptive suspect probably would attempt to follow a remem-
bered script. In subsequent interviews, deceptive criminal suspects are repeat-
ing an originally deceptive account rather than trying to reconstruct an account
that actually occurred. Thus, they will use fewer words and give fewer details
with repeated interviews in an attempt to ensure that their recall will appear
accurate and credible. Coarsely grained but credible responses, as opposed to
more specifi c responses, would appear to be the preferred and wiser choice for
deceptive suspects. In contrast, because memory is reconstructive, it would be
expected that truthful reports will gain, lose and change information over time
and, in an attempt to be more informative, will show more fi ne - grained
responses (Loftus, 1979 ; Baddeley, 1990 ; Goldsmith, Koriat & Weinberg -
Eliezer, 2002 ).
The fact that the mean scores for correspondence of activities at one day were
highly similar for both truthful and deceptive participants deserves particular
consideration. Both truthful and deceptive suspects reported approximately
one - third of the total possible number of activities observed by the research
assistant. The ‘ repeat vs. reconstruct ’ hypothesis would predict that truthful
accounts should contain more details than deceptive accounts. So what can
account for these fi ndings? As Granhag & Str ö mwall (2000) theorize in their
own study, participants in the current study were asked to distort an original
event rather than create a complete fabrication. Distortions may in general
contain a greater number of details than pure fi ction, potentially negating the
effects of deception on the number of details initially reported by participants.
Furthermore, in this investigation both truthful and deceptive suspects oper-
ated in the very familiar surroundings of their own home and nearby streets.
The context of the events for both deceptive and truthful suspects would have
been relatively similar in terms of visual, auditory and spatial details. Performing
a mock crime in familiar surroundings would have been highly conducive
for the construction of logical and well - rehearsed reports by the deceptive
suspects. Such familiarity would facilitate credible and logical stories by both
deceptive and truthful suspects.
Additionally, our fi ndings support the basic premise of the hypothesis put
forth by Undeutsch (1982) , which argues that fewer details are provided by
deceptive individuals because it is relatively easier to recall fewer details later.
Thus, in actual forensic settings in which a criminal suspect is interviewed
repeatedly, the number of details and the length of particular accounts over
time may be important clues to veracity. Note that these are not absolute
quantities but relative ones in which the point of comparison is the individual
him - or herself. Individuals vary greatly in the number of words and details
that they use in general, and this is based on a variety of factors, including
intelligence, educational level and language profi ciency. In an initial interview,
it is thus diffi cult if not impossible to predict how many words and details
might be used. But over time with repeated interviews one may see decreases
in quantities and fi ne details, and these decreases can serve as important indica-
tors of deception.
Truthfulness in Witnesses’ and Suspects’ Reports
295
Interestingly, neither truthful nor deceptive suspects reported what they did
during the walk, apart from stating that they were going for the walk. It is
likely that no disclosures were given regarding activities undertaken during the
walk because participants were repeatedly instructed by the research assistant
not to reveal into which group they had been placed. These fi ndings suggest
that our participants were highly compliant in following the experimental
instructions. Furthermore, the methodology used in this investigation (written
free responses without direct questioning from the mock police offi cer) prob-
ably contributed to the lack of details reported by participants during the walk.
Follow - up studies of the present investiga
tion should investigate the differ-
ences between truthful and deceptive suspects as a function of type of interview
and suspect responses.
This study provides preliminary support for the equal ease with which
both deceptive and truthful participants can effectively account for their time
during an event or series of events. Thus, asking a criminal suspect when an
event took place or how long that event lasted may not be a reliable clue to
deception if the act of deception has no differential effect on one ’ s ability to
estimate its duration. Recall of event duration is seen by legal experts to have
potential signifi cance in the courtroom. In her article directed to defence
lawyers, Steele (2004) advises that attention should be paid to ‘ Event Duration
… for how long did the witness see the culprit? … the witness ’ estimate is
almost certain to be wrong; generally, the witness will overestimate durations ’
(p. 10). Although the witnesses referred to by Steele are victims of or
bystanders to a crime, it is also true that guilty suspects are witnesses to
their own involvement in a crime. In the present investigation truthful sus-
pects and deceptive suspects did not differ in their duration estimations for
routine, mundane events. However, deceptive participants in contrast to
truthful participants signifi cantly and consistently underestimated the duration
of ‘ the walk ’ (the point during the study when participants were asked to go
out and fi nd either the bank note or advertisement). Note that the research
literature on duration estimations for events lasting three minutes or less is
highly reliable, that is, short - duration events are on average overestimated (see
Yarmey, 2000 ). The implications of this fi nding are potentially considerable,
particularly given the lack of signifi cant fi ndings for any of the other duration
estimates. The key experimental manipulation of being assigned to either
the truthful or deceptive condition is made most salient to participants when
they are instructed to go out for the walk. Although they already know
whether they will be behaving truthfully or deceptively, ‘ the walk ’ is the point
at which these instructions actually become an event that the participants must
act upon.
The practical psycho - legal implications of the current study centre on the
Handbook of Psychology of Investigative Interviewing: Current Developments and Future Directions Page 56
