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Defendants and witnesses are often intoxicated by alcohol. We investigated whether memory and resistance to suggestive cues are undermined at blood alcohol concentrations (BACs) that were (close to) zero (MBAC = 0.01%), moderate (MBAC = 0.06%), or high (MBAC = 0.16%). Participants (N = 67) were approached in bars and instructed to commit a mock crime. Immediately after this, their memory and susceptibility to suggestive questions were tested, and these were re-tested during a sober follow-up 3–5 days later. Compared with sober participants, moderate and severe intoxication was associated with lower levels of correctly recalled crime details during both test sessions (i.e. intoxicated and sober). Also, during both sessions, severely intoxicated participants displayed a greater tendency to go along with suggestive cues compared with sober participants. Thus, intoxication impaired memory and increased suggestibility during an immediate interview, and both effects persisted when sober again. Copyright © 2015 John Wiley & Sons, Ltd.
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Alcohol Intoxication Impairs Memory and Increases Suggestibility for a Mock Crime:
A Field Study
K. VAN OORSOUW*, H. MERCKELBACH and T. SMEETS
Forensic Psychology Section, Maastricht University, Maastricht, The Netherlands
Summary: Defendants and witnesses are often intoxicated by alcohol. We investigated whether memory and resistance to sugges-
tive cues are undermined at blood alcohol concentrations (BACs) that were (close to) zero (M
BAC
= 0.01%), moderate
(M
BAC
= 0.06%), or high (M
BAC
= 0.16%). Participants (N = 67) were approached in bars and instructed to commit a mock crime.
Immediately after this, their memory and susceptibility to suggestive questions were tested, and these were re-tested during a sober
follow-up 35 days later. Compared with sober participants, moderate and severe intoxication was associated with lower levels of
correctly recalled crime details during both test sessions (i.e. intoxicated and sober). Also, during both sessions, severely intoxi-
cated participants displayed a greater tendency to go along with suggestive cues compared with sober participants. Thus, intox-
ication impaired memory and increased suggestibility during an immediate interview, and both effects persisted when sober again.
Copyright © 2015 John Wiley & Sons, Ltd.
INTRODUCTION
Alcohol interferes with the transference of information from
short- to long-term memory because it disturbs the encoding
and consolidation of new information (Ray & Bates, 2006;
Söderlund, Parker, Schwartz, & Tulving, 2005; Verster,
Van Duin, Volkerts, Schrueder, & Verbaten, 2003; White,
2003). During intoxication, encoding is more supercial
due to a lack of rehearsal and other mnemonic strategies
(Saults, Cowan, Sher, & Moreno, 2007). Even a relatively
modest but sudden rise in blood alcohol concentrations
(BACs) may produce fragmentary blackouts or grayouts
(Perry et al., 2006; Ray & Bates, 2006; Wetherill & Fromme,
2011; White, 2003). This means that parts of the event(s)
that took place during intoxication are not consolidated and
not remembered afterwards. Higher BACs may even lead
to a complete (i.e. en bloc) blackout, that is, a total inability
to recall events at a later point in time (Goodwin, Othmer,
Halikas, & Freeman, 1970; Kalant, 1996; Mintzner &
Grifths, 2002; Van Oorsouw, Merckelbach, Ravelli,
Nijman, & Mekking-Pompen, 2004). Number of drinks
and also the rate at which they are consumed are important
predictors of grayouts and blackouts. The faster the con-
sumption rate, the more rapid intoxication levels rise (see
also Goodwin, Crane, & Guze, 1969; White, 2003). In the
study by Van Oorsouw et al. (2004), participants with black-
outs reported having consumed about 15 drinks within
4 hours. This corresponds with BACs of up to 0.26%. To
put this further into perspective, in the Netherlands, the max-
imum concentration of blood alcohol at which it is legally
permitted to drive a motor vehicle is 0.02% (approximately
2 drinks within 1 hour); in the United States, this level is
0.08% (approximately 5.5 drinks within 1 hour).
1
Suspects, victims, and witnesses of crimes are often under
the inuence of alcohol (Evans, Schreiber Compo, &
Russano, 2009; Haggard-Grann, Hallqvist, Langstrom, &
Moller, 2006). For example, 35% of the offenders who have
been convicted for violent crimes claim alcohol-related am-
nesia for their offence (Cima, Nijman, Merckelbach, Kremer,
& Hollnack, 2004; Kopelman, 1995). Although some of them
may have been simulating their amnesia (e.g. van Oorsouw &
Merckelbach, 2009), many of them are likely to have been
intoxicated during the crime.
Given that alcohol may impair memory, one would expect
police ofcers to refrain from interrogating an intoxicated
suspect or witness. Nevertheless, Evans et al. (2009) noted
in their survey conducted among police investigators that
22% of them said that they were willing to interrogate an in-
toxicated suspect. Only 7% of the police investigators said
that they would allow the suspect to become sober before
they would start the interrogation (Evans et al., 2009; see
also Sigurdsson & Gudjonsson, 1994; Santtila, Ekholm, &
Niemi, 1998). Likewise, an analysis of police les by
Palmer, Flowe, Takarangi, and Humphries (2013) demon-
strated that police investigators asked intoxicated witnesses
to describe the culprit and to take an identication test just
as often as they asked sober witnesses. For the subgroup of
intoxicated suspects, it was not clear whether they were
actually questioned about the crime while still being intoxi-
cated. However, the majority of the arrested offenders were
taken into custody while under the inuence of alcohol,
rendering it likely that they were still intoxicated when
questioned.
A recent police survey in the Netherlands revealed that
50% of the professionals believe that perpetrators, including
those who are intoxicated, are more likely to disclose crucial
information in an immediate interrogation (Van Oorsouw,
Merckelbach, & Willems, 2013). This assumption is not sur-
prising because police investigators are familiar with the
phenomenon that memory fades over time.
Given that police investigators often deal with intoxicated
suspects and witnesses and question them in both intoxicated
and sober states, it is important to study the doseresponse
effect of alcohol on memory. Previous studies in this domain
have yielded mixed results. For example, regarding intoxi-
cated eyewitnesses (BAC range: 0.060.12%), Hagsand,
Roos af Hjelmsäter, Granhag, Fahlke, and Söderpalm-Gordh
1
For a male person weighing 80 kg.
*Correspondence to: Kim van Oorsouw, Department of Clinical Psychological
Science, Forensic Psychology Section, Maastricht University, PO Box 616,
6200 MD, Maastricht, The Netherlands.
E-mail: K.vanoorsouw@maastrichtuniversity.nl
Copyright © 2015 John Wiley & Sons, Ltd.
Applied Cognitive Psychology,Appl. Cognit. Psychol. 29: 493501 (2015)
Published online 17 April 2015 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/acp.3129
(2013a) demonstrated that at moderate dosages (mean BAC
0.06%), alcohol impaired the number of details that partici-
pants recalled of a crime video. However, intoxication level
did not affect memory accuracy. Similar ndings were re-
ported by Hildebrand Karlén, Roos af Hjelmsäter, Fahlke,
Granhag, and Söderpalm-Gordh (2014), but only for women
(mean BAC 0.08%) and not for men (mean BAC 0.07%). On
the other hand, Schreiber Compo et al. (2012) found that in-
toxicated individuals (with BACs ranging between 0.06%
and 0.08%) who watched a staged theft did not differ from
sober participants in either memory completeness or accu-
racy. In another study, Hagsand and colleagues investigated
the effect of similar dosages on participantsidentication
accuracy (i.e. identifying a culprit) in a simultaneous
target-absent or target-present lineup, after they had watched
a crime video (Hagsand, Roos af Hjelmsäter, Granhag,
Fahlke, & Söderpalm-Gordh, 2013b). Participants who had
been intoxicated while watching the movie later performed
at a similar levelwhich was indicative of overall poor
lineup performance (i.e. 25% correct identications)as
their sober counterparts. Similar ndings were reported by
Harvey, Kneller, and Campbell (2013) at slightly higher dos-
ages. These researchers employed a slide sequence depicting
a theft. Again, no effect of alcohol was found on subsequent
identication accuracy in a simultaneous target-absent or
target-present lineup. Importantly, in both studies, partici-
pants were sober when tested. Thus, it appears that recogni-
tion memory is relatively unaffected by alcohol intoxication.
An exception to this rule is the study by Dysart, Lindsay,
MacDonald, and Wicke (2002). These authors did nd a det-
rimental effect of alcohol on identication accuracy, but only
in target-absent show-ups. However, their study differed in
important respects from the studies cited earlier. First, partic-
ipants were involved in a real-life interaction rather than pas-
sively watching a movie or slide sequence. Second, partici-
pants were still intoxicated (BACs ranging between 0.00%
and 0.20%) when asked to identify the person they had
interacted with. Third, the authors did not use a lineup but
a single picture (i.e. a show-up). A meta-analysis by Steblay,
Dysart, Fulero, and Lindsay (2003) demonstrated that line-
ups and show-ups do not generate different rates of false
identications. Still, the Dysart et al. nding of a heightened
rate of false identications in intoxicated witnesses might be
the result of a subtle interaction between suggestive show-
ups and intoxication.
In the older study of Yuille and Tollestrup (1990), sober
and intoxicated individuals were exposed to a mock crime.
Although free recall of the intoxicated participants (BACs
ranging between 0.06% and 0.12%) was impaired, they
did not differ from sober participants in the accuracy with
which they identied the presence or absence of the culprit
in a lineup 1 week later, when sober again. Taken together,
these studies suggest that identication accuracy is only
undermined when participants are intoxicated at the time
of testing (Dysart et al., 2002), and not when sober again
(Yuille & Tollestrup, 1990).
Only two studies have looked at intoxicated offenders
memories for crime details. Using a staged mock crime,
Read, Yuille, and Tollestrup (1992) investigated intoxicated
participantsmemory for what they did (as perpetrators) and
their memory for what they saw (as witnesses) in an imme-
diate and/or delayed (1 week later) memory test. Alcohol
intoxication (with BACs up to 0.10%) undermined perpe-
tratorsmemory for the mock crime, but not witnesses
identication accuracy. The memory-undermining effect of
alcohol was not affected by the time of testing (immediate
and/or delayed). Yet, repeated testing did improve memory,
irrespective of intoxication level. In a eld study, Van
Oorsouw and Merckelbach (2012) tested memory for a staged
robbery lmed from the perpetrators perspective when
participants were sober again. The authors noted that intoxi-
cation (with BACs up to 0.24%) during exposure to the
lm fragment impaired completeness and accuracy of
delayed (35 days later) recall.
Most studies on alcohol and memory focussed on
witnessed events rather than enacted events. This is an im-
portant limitation: Crimes mostly involve action rather than
passive states, and memory for enacted events is better than
memory for witnessed events (Engelkamp, 1995). The rea-
son for this is that arousal is likely to be higher during an
enacted event as compared with passively watching a crime
video. Raised arousal levels might counteract the memory-
undermining effect of alcohol (Engelkamp, 1995; Read
et al., 1992).
With these considerations in mind, it is ecologically rele-
vant to employ mock crimes when testing the effects of alco-
hol on crime-related memories. In doing so, it is informative
to look not only at memory performance but also at suggest-
ibility. Note that only a few studies have addressed the link
between alcohol intoxication and suggestibility. Germane
to this is the well-documented discrepancy-detection princi-
ple that dictates that people are more prone to misleading
cues when their memory of the original event is poorer
because it becomes more difcult for them to detect discrepan-
cies between truly encoded details and merely suggested
details (Peterson, Rotheisch, Zelazo, & Pihl, 1990; Schooler
& Loftus, 1986). Because alcohol undermines the encoding of
detailed information, one expects intoxication to lead to prob-
lems in detecting discrepancies between stored information
and information merely suggested during, for example, a po-
lice investigation. This, in turn, would lead to increased sug-
gestibility by rendering the discrimination between falsely
suggested and actual details exceedingly difcult. In line with
this, Nash and Takarangi (2011) found in their survey among
individuals with blackout experiences that they often tend to
rely on less credible resources to ll in the gaps. Consequently,
being exposed to inaccurate information (e.g. in a suggestive
interview, or by co-witnesses or other external sources) could
more easily make people with blackouts believe inand remem-
ber experiences that never occurred (Loftus, 2005; Mazzoni &
Kirsch, 2002; Nash & Takarangi, 2011).
So far, only Santtila, Ekholm, and Niemi (1999) directly
investigated the link between alcohol and suggestibility.
These authors found that intoxicated individuals exhibited
areduced susceptibility to go along with leading questions,
as measured with the Gudjonsson suggestibility scale
(Gudjonsson, 1997). They concluded that intoxicated indi-
viduals may become less vulnerable to suggestive inuences
because of the anxiolytic properties of alcohol (Santtila et al.,
1999). The rationale behind this idea is that anxietyfor
494 K. van Oorsouw et al.
Copyright © 2015 John Wiley & Sons, Ltd. Appl. Cognit. Psychol. 29: 493501 (2015)
example, fear of giving the wrong answer during an
interviewis an important antecedent of suggestibility.
However, Santtila et al. relied on an experimental procedure
that deviated strongly from the order of events in real-life
settings. Their participants rst experienced an event; next,
they were given alcohol, only to be questioned in a sugges-
tive way about the target event in the nal phase of the pro-
cedure. Thus, Santtila et al. did not address the short- and
long-term suggestibility of offenders or witnesses who were
intoxicated while undergoing the critical event. This is an
important omission because, in reality, the perpetrator is of-
ten questioned about events that took place while he or she
was intoxicated. In addition, when alcohol is consumed after
encoding of an event, it may paradoxically enhance memory
for the event through its inhibition of retrograde interference
(i.e. the retrograde enhancement effect; Bruce & Pihl, 1997;
Knowles & Duka, 2005). This effect could explain why
Santilla et al. did not nd an increase but rather a decrease
in suggestibility after intoxication. Thus, the Santtila et al.
study does not provide an optimal test of the idea that alco-
hol induced discrepancy-detection problems may contribute
to increased suggestibility in former intoxicated offenders.
The aims of the present study were threefold. First, we
tested whether alcohol would undermine memory for an
event (i.e. mock crime) enacted in a perpetrator role. Second,
we investigated whether intoxication would increase sug-
gestibility in an interrogation situation. And third, we ex-
plored whether participants who were intoxicated during
the critical event remember more correct details when inter-
rogated immediately (while still intoxicated) or when sober
again in a repeated interview about the event.
We hypothesized that compared with low and moderate
levels of intoxication, higher levels (i.e. BACs above
0.11%) at the time of encoding (i.e. during the mock crime)
would be detrimental to the accuracy and completeness of
memory for crime details when participants are tested imme-
diately following the mock crime. Based on the idea that in-
toxication interferes with encoding, this effect was expected
to persist during a follow-up test when participants were so-
ber again. With respect to suggestibility, we hypothesized
that alcohol intoxication would increase suggestibility owing
to difculties in discrepancy detection that arise when people
have memory decits due to alcohol.
METHOD
Participants
Potential participants (mixed sample) were approached in
three local bars in Maastricht, the Netherlands. These were
regular bars with a mixed audience (e.g. students and work-
ing class people). Each participant was approached and
tested individually. Participants were approached when it
was evident that they were adults (>18 years), and when
they made a healthy impression. When they appeared to be
heavily intoxicated, they were not approached for participa-
tion. Participants were not further screened in any way. In
total, 100 volunteers agreed to participate, and 67 of them (54
men) completed both the session in the bar and the follow-up
session. Their mean age was 22.2 years (range, 1836 years;
SD = 2.53). The study was approved by the local standing
Ethical Research Committee. Participants were asked not to
talk to others about the experiment until after the second
session.
Mock crime
The mock crime consisted of an introduction story and a
criminal act that participants had to perform. The 2-minute
introductory crime story was presented to them via head-
phones. This was carried out to eliminate distraction noise
and to ensure that the story was read to each participant in
the same pitch and volume. The introduction was as follows:
You have been working at this bar for a while now.
Usually you get paid on the last Friday of the month.
However, your boss has not paid you for the last two
months. Tonight you have a day off and you are in this
bar with your friends. You know your boss keeps the
daily cash turnover in a briefcase that is in his ofce,
where the coats of the staff are also stored. You suspect
that the key to the briefcase is inside his coat pocket.
You decide to sneak into your bossofce and steal some
of his money you know he keeps in a briefcase.
2
Next, participants were asked to enter a room that was deco-
rated as an ofce (e.g. a coat stand with coats, posters on the
wall, a table with owers, and a briefcase). They were
instructed to search for a key that was in one of the coats
and to use it to open the briefcase. They were then asked
to steal the money from the briefcase. There were also other
objects (e.g. an orange and a picture) in the briefcase. How-
ever, the instructions did not mention any details they were
going to encounter (e.g. ringing of a phone and objects inside
the briefcase). After the instruction had been given, partici-
pants were asked whether they understood the procedure.
As a manipulation check, participants were asked to rate
their emotional involvement and ability to empathize with
the main character using two 100 mm (1 = not emotionally
involved/extremely difcult to empathize, 100 = very emo-
tionally involved/very easy to empathize) visual analogue
scales.
Procedure
Participants were approached in bars between 20.00 h and
04.00 h and were invited to participate in a study on alcohol
and cognition. They signed an informed consent form after
which their BAC was measured, using the Lion Alcometer
SD400. This breath analyser converts the breath alcohol ratio
into blood alcohol ratio. Next, participants were asked sev-
eral questions about their drinking habits and drug use
(Van Oorsouw & Merckelbach, 2012). We also asked them
to provide us with contact information so that we could send
them a debrieng form and their BAC level afterwards. At
that moment, nothing was mentioned about follow-up testing
because we did not want to inuence participants in any
way. Next, participants were taken into a quiet room where
they received the instructions for the mock crime. They were
2
A detailed description can be obtained from the rst author.
Intoxication, memory, and suggestibility 495
Copyright © 2015 John Wiley & Sons, Ltd. Appl. Cognit. Psychol. 29: 493501 (2015)
asked to identify with the main character of the story that
they were about to hear. The story was administered to them
through headphones. Following this, they were given the in-
structions to commit the actual mock crime as described ear-
lier. After having carried out the mock crime, participants
were taken into a different, adjacent room where their mem-
ory and level of suggestibility were tested (i.e. immediate
test). The interview was conducted by a different person than
the one who approached participants and explained the pro-
cedure. Participantsresponses were audiotaped using voice
recorders. There was an inte rval of approximately 10 min be-
tween the invitation to participate in the study and the start of
the interview. When all tests were completed, participants
were thanked and informed that they would be contacted
within the next 35 days for a follow-up test. Participants re-
ceived a candy bar for their participation.
Three to ve days later, participants were contacted by
phone and asked to complete several tests about the mock
crime. When they agreed, the free and cued recall instruc-
tions and suggestibility items employed during test 1 were
once more administered. Thus, they were instructed to report
as completely as possible about the mock crime and its intro-
ductory story. The response rate was 67%. Prior to the
follow-up test, participants were asked whether they had
been drinking alcohol. To reduce the chance of participants
being intoxicated during the follow-up test, testing took
place at weekdays between 9.00 h and 16.00 h. None of the
participants said they had been drinking alcohol prior to
the second test. Again, responses were audiorecorded. After
completion of the follow-up test, participants were thanked
and provided with information about their level of intoxica-
tion during the rst test session. After the study was nished,
all participants were fully debriefed by e-mail.
Memory testing and scoring
Participantsmemory for the mock crime was tested both im-
mediately after their return from the ofce space and at the
follow-up session.
3
Memory testing consisted of a free recall
test and a cued recall test. For the free recall test, participants
were asked to give a detailed description of their motive, the
surroundings, and the objects they had seen, as well as their
own actions. Thus, they were instructed to recall everything
they remembered of both the introductory story and the theft.
The cued recall test consisted of 15 memory questions of the
following type: When did you usually get paid?and What
objects were located in the briefcase?The questions
pertained to the details mentioned in the introductory story
as well as details of the mock crime.
An a priori scoring protocol was employed to evaluate
participantsfree and cued recall (see for a similar method
Van Oorsouw & Merckelbach, 2012). In total, 27 informa-
tional units were identied in the introductory story and 29
units in the mock crime. Thus, the maximum number of de-
tails was 56. Examples of informational units that were
scored in the story are: my boss did not pay me(1 point);
for two months(1 point). As for the mock crime, points
were accredited when participants correctly described ac-
tions, for example, that they took the key out of the coat
pocket (1 point) and that they opened the briefcase (1 point).
Extra points were given when participants correctly specied
the amount of stolen money (e.g. 50 euros), mentioned the
colour of the wallet, and so on. One point was accredited
to each unit that was accurately recalled. The number of cor-
rect units represented the total free recall score.
The 15 cued recall questions covered a total of 21 critical
information units. For each correct answer to a question, par-
ticipants received 1 point, except for the question about the
objects in the briefcase. Here, participants could earn 7 points
if they mentioned all objects correctly, adding to a total free
recall score of 21. Most questions pertained to the enacted
event and the objects involved [e.g. the briefcase (17 points)],
and only four questions were about the introductory story and
referred to the motive for stealing the money (4 points).
Apart from the numbers of correctly free- and cued-
recalled details, we evaluated two types of errors. Commis-
sion errors were dened as the introduction of an entirely
new and false piece of information (e.g. the briefcase
contained a cell phone). Distortion errors were dened as
pieces of information that were essentially correct, but
misrepresented during the cued recall test. An example of a
distortion would be I took the key from the blue coatwhen
in fact the coat was grey.
Free and cued recall tests were scored by the rst author and
an independent second rater. Both were blind as to partici-
pantsintoxication levels. Pearson correlations between the
two raters for the number of correctly recalled units during free
(range: 056) and cued (range: 0 21) recall were 0.98 and
0.91, respectively. For commission and distortion errors, these
correlations were 0.85 and 0.76, respectively (all ps<0.01).
Suggestibility measure
Suggestibility was assessed using 15 misleading questions
that were intermixed with the 15 cued recall memory ques-
tions. The misleading questions pertained to details that
had not been present in the story or during the mock crime.
For instance, we asked participants Did the wallet contain
50 or 100 euros?when in fact it contained 70 euros. We also
gave participants questions containing two false alternatives
such as Was there an apple or a banana in the briefcase?
when in fact the briefcase contained an orange. When partic-
ipants yielded to a misleading question, this was scored with
1 point. In line with the procedure described by Gudjonsson
(1997), participants received negative feedback after com-
pletion of the 30 cued recall and misleading questions. That
is, they were told that they made quite a few mistakes and
were asked to answer the questions for a second time. We
were interested in whether negative feedback would lead to
changes (shifting) in participantsanswers to the second
series of (misleading) questions. This way, we were able to
calculate three suggestibility parameters: (i) the tendency to
go along with misleading questions immediately (yield 1);
(ii) the tendency to accept misleading cues after negative
feedback (yield 2); and (iii) the tendency to change an an-
swer after negative feedback (shift).
3
Participants were rst contacted after 3 days but were not always available
to undergo the follow-up test. In those cases, the follow-up test was sched-
uled for the next day or 2 days later. The 3- to 5-day interval was also used in
previous studies (e.g., Van Oorsouw & Merckelbach, 2012).
496 K. van Oorsouw et al.
Copyright © 2015 John Wiley & Sons, Ltd. Appl. Cognit. Psychol. 29: 493501 (2015)
RESULTS
Statistical analyses
To examine how different levels of intoxication affected
memory and suggestibility, both recall data and suggestibil-
ity scores were subjected to 3 (groups: nearly sober vs. mod-
erately intoxicated vs. severely intoxicated) × 2 (sessions:
immediate vs. follow-up) analyses of variance (ANOVAs),
with the last factor being a repeated measure. Follow-up
pairwise comparisons between groups were carried out. Re-
gression analyses were conducted to explore whether BAC
and/or memory affected suggestibility.
Blood alcohol concentrations and memory performance
Blood alcohol concentrations ranged from 0.00% to 0.26%,
with an average BAC of 0.09% (SD = 0.07).
Following the approach of Van Oorsouw and
Merckelbach (2012), participants were subdivided in three
groups: sober (BACs <0.02%),
4
moderately intoxicated
(BACs between 0.02% and 0.11%), and severely intoxicated
(BACs >0.11%). The sober group consisted of 14 partici-
pants (M
BAC
= 0.01%, SD = 0.01), the moderately intoxicated
group had 27 participants (M
BAC
= 0.06%, SD = 0.02), and
the severely intoxicated group had 26 participants
(M
BAC
= 0.16%, SD =0.04). As was to be expected, the
groups differed in the number of alcoholic beverages partic-
ipants reported to have drank on the night of testing [F(2,
64) = 36.75, p<0.01, η2
p= 0.53]. Sober, moderately intoxi-
cated, and severely intoxicated participants reported to have
consumed respectively 4 (SD = 2.7), 9 (SD = 3.7), and 17
(SD = 6.3) alcoholic beverages.
5
Groups did not differ in
self-reported number of drinking nights per week [F(2, 64) =
1.00, p= 0.37], or the number of drinks on a typical drinking
occasion [F(2, 64) = 1.28, p= 0.28].
On the whole, participants reported they were able to iden-
tify with the main character of the mock crime (M= 71.2,
SD = 18.6) and felt emotionally involved in the mock crime
(M= 66.6, SD = 20.3). There were no group differences in
the ability to empathize or in emotional involvement in role
playing the thief [both Fs<1.0].
Table 1 shows memory performance data (correct free re-
call, cued recall, and errors for the story and actions, respec-
tively) of the three groups during the two test sessions for
free recall and cued recall.
A repeated-measure ANOVA performed on free recall of
the introductory story, with group (sober, moderately, and se-
verely intoxicated) as a between-subject factor and session as
a repeated measure, revealed no interaction between groups
and session [F(2, 64) <1.0, η2
p= 0.04], or an effect of session
[F(1, 64) = 2.43, p= 0.12, η2
p= 0.04]. Yet, a signicant main
effect of group [F(2, 64) = 24.00, p<0.01, η2
p= 0.45] did
emerge. Bonferroni corrected post hoc t-tests revealed that
during both sessions, the three groups differed signicantly
in the number of correctly recalled story details, with intoxi-
cation resulting in signicant lower levels of correct recall
(Table 1). No signicant main effects or an interaction effect
was found for number of errors made in recalling the intro-
ductory story (all Fs<1.40, all ps>0.05).
For free recall of the enacted event, no interaction [F(2,
58) = 1.11, p= 0.33, η2
p= 0.03]
6
was found. But main effects
emerged for session [F(1, 58) = 20.93, p<0.01, η2
p= 0.26]
and group [F(2, 58) = 7.21, p<0.01, η2
p= 0.20]. Sober partic-
ipants recalled signicantly more correct details as compared
with both intoxication groups during both sessions (both
ts>2.23, both ps<0.05), and all groups recalled
4
Although participants in this group had consumed alcohol, their BAC was
below the Dutch legal driving limit (0.02%) according to which they would
be legally perceived as sober. Therefore, this group will be referred to as the
sober group.
5
An alcoholic beverage refers to a standard glass of beer, wine, spirits, or a
mixed drink.
Table 1. Number of correctly recalled details and errors for the three groups on the free and cued recall test, during session 1 (T1) and the
follow-up test (T2)
Sober (n= 14) Moderately intoxicated (n= 27) Severely intoxicated (n= 26)
T1 T2 T1 T2 T1 T2
Free recall story
Correct total 14.15 (4.93)
a,b
13.30 (4.31)
a,b
11.18 (3.51)
c
10.07 (3.51)
c
6.23 (3.59) 5.90 (3.20)
Errors (com/dis) 1.76 (1.16) 1.92 (1.38) 1.88 (1.36) 1.70 (1.26) 2.04 (2.26) 1.23 (1.04)
Free recall actions
Correct total 8.38 (5.31)
a,b
12.93 (5.57)
a,b,
* 5.70 (3.97) 7.88 (4.21)* 5.04 (2.72) 7.42 (4.35)*
Errors (com/dis) 0.31 (0.48) 0.76 (0.83) 0.18 (0.48) 0.92 (1.46) 0.47 (0.81) 0.61 (0.92)
Cued recall story
Correct total 2.71 (0.91) 2.50 (1.16) 2.44 (1.25) 2.29 (1.20) 2.03 (1.39) 1.80 (1.47)
Errors (com/dis) 1.14 (0.94) 1.35 (1.00) 1.18 (1.37) 1.14 (1.09) 1.69 (1.37) 1.65 (1.44)
Cued recall actions
Correct total 11.71 (1.47)
b
12.35 (1.90)
b
10.59 (2.37)
c
10.51 (1.98) 8.80 (2.36) 10.03 (3.05)*
Errors (com/dis) 0.42 (0.85) 0.21 (0.80) 0.62 (1.00) 0.05 (1.06) 1.23 (1.72) 1.11 (1.27)
Totals and errors (commission and distortion errors; com/dis) are displayed separately for the introductory story (recall story) and enacted event (recall actions).
a
p<0.05 between sober and moderately intoxicated groups.
b
p<0.05 between sober and severely intoxicated groups.
c
p<0.05 between moderately and severely intoxicated groups.
*p<0.05 within this group between sessions.
6
For six participants, data were partly missing on either the rst or the sec-
ond session.
Intoxication, memory, and suggestibility 497
Copyright © 2015 John Wiley & Sons, Ltd. Appl. Cognit. Psychol. 29: 493501 (2015)
signicantly more correct details of the enacted event during
the second test session (all ts>2,22, all ps<0.05; Table 1).
Regarding errors made in recalling the enacted event, only a
signicant effect of session was found [F(2, 58) = 7.64,
p<0.01, η2
p= 0.12]. Follow-up tests indicated that this effect
was carried entirely by the moderately intoxicated partici-
pants, who made more errors in recalling the enacted event
when they were sober as compared with when they were in-
toxicated [t(26) = 2.92, p<0.01].
As for cued recall of the introductory story, only a signicant
main effect of session was found [F(1, 64) = 5.04,
p<0.05, η2
p= 0.07]. All groups recalled fewer correct
details of the introductory story during the second (sober)
test. An ANOVA on the number of errors that were made
during cued recall of the introductory story yielded no
effects (all Fs<1.30).
Regarding cued recall of the enacted event, signicant
main effects for session [F(1, 64) = 7.56, p<0.01, η2
p
= 0.11] and group [F(2, 64) = 6.74, p<0.01, η2
p= 0.17] and
a signicant interaction between group and session was
found [F(2, 64) = 5.04, p<0.01, η2
p= 0.11]. To break down
this interaction, we carried out univariate follow-up
ANOVAs for both sessions separately, with group as a
between-subject factor. Signicant between group differ-
ences were found in correct cued recall scores obtained dur-
ing session 1 [F(2, 64) = 9.10, p<0.01, η2
p= 0.22] and ses-
sion 2 [F(2, 64) = 4.23, p<0.05, η2
p= 0.12]. During the rst
test session, severely intoxicated participants recalled signif-
icantly fewer correct details of the enacted event relative to
the other two groups [both ts>2.96, both ps<0.05]. This
effect persisted during the second session [t(64) = 2.85,
p<0.05], but only so when severely intoxicated participants
were compared with sober participants. Also, participants in
the severe intoxication group recalled signicantly more cor-
rect details during the second (sober) than during the rst test
[t(25) = 3.12, p<0.01]. The group effect in the number of
errors made in recalling the enacted event was close to
reaching signicance [F(2, 64) = 2.98, p= 0.058, η2
p= 0.08].
That is, compared with sober participants, participants in
the severe intoxication group had a tendency to make more
errors during both sessions.
Suggestibility
Yield and shift scores of the three groups are shown in
Table 2. For yield scores, no interaction effect [F(2, 64) <
1.0], or an effect of session emerged [F(1, 64) <1.0]. Yet,
there was a signicant main effect of group [F(2, 64) = 4.49,
p<0.01, η2
p= 0.12]. During both sessions, severely intoxi-
cated participants displayed a stronger tendency to go along
with misleading questions compared with sober participants
[t(39) = 2.94, p= 0.01]. No other group differences in yield
scores were apparent [ts<1.78, ps>0.24].
Shift scores revealed no interaction between intoxication
level and session [F(2, 64) <1.0]. Neither was there a signif-
icant group effect for the tendency to shift answers after
negative feedback [F(2, 64) <1.0]. However, a signicant
main effect was found for sessions [F(1, 64) = 19.50,
p<0.01, η2
p= 0.24]. Exploratory analyses showed that shift
scores decreased signicantly over sessions for both intoxi-
cation groups [both ts>2.95, both ps<0.01], but not for so-
ber participants [t= 1.53, p= 0.15].
Regression analyses
For both free and cued recall tests, we calculated Pearson
correlations between BACs, free and cued recall for the in-
troductory story and enacted event, and suggestibility (yield-
ing and shifting). The correlational patterns for both sessions
are given in the Supporting information.
There was a negative correlation between BAC and mem-
ory performance ranging from r=0.32, p<0.05 to
r=0.60, p<0.01 during both sessions. Similarly, signi-
cant negative correlations existed between suggestibility
and several, but not all, memory output measures (Table 1
Supporting information). Yet, BAC only correlated nega-
tively with yielding to suggestive questions (r= 0.32,
p<0.01 for sessions 1 and 2).
Using regression analyses, we investigated whether mem-
ory performance mediated the relationship between BAC
level and yielding. Such pattern would be in line with the no-
tion that failure to detect discrepancies between misleading
information and the (poorly encoded) actual event underlies
increased suggestibility in intoxicated individuals. A linear
regression analysis was conducted with yield scores as de-
pendent variable and BAC and proportions correct free recall
and cued recall elements for story and actions as independent
variables. Backwards elimination with a criterion of p<0.05
resulted in a model in which free recall of story details was
predictive of yield scores during the rst test session.
This model accounted for 22% of the variance. A similar
analysis was carried out for the follow-up test session,
now including BAC and all memory performance vari-
ables for the rst and second test sessions. Yield scores
during the second test were predicted by free recall of
story and action details at session 1, accounting for 28%
of the variance (Table 3).
Table 2. Yield and shift scores for the three groups during session 1 (T1) and the follow-up test (T2)
Sober (n= 14) Moderately intoxicated (n= 27) Severely intoxicated (n= 26)
T1 T2 T1 T2 T1 T2
Yield 3.00 (3.01)
a
2.80 (2.96)
a
3.93 (2.67) 4.56 (2.72) 5.42 (2.85) 5.73 (3.31)
Shift 3.86 (4.52) 2.64 (3.00) 3.41 (2.81) 1.89 (2.19)* 4.54 (4.31) 2.29 (3.26)*
a
p<0.05 between sober and severely intoxicated groups.
*p<0.05 within this group between sessions.
498 K. van Oorsouw et al.
Copyright © 2015 John Wiley & Sons, Ltd. Appl. Cognit. Psychol. 29: 493501 (2015)
DISCUSSION
A quick glance at the extant literature on alcohol intoxication
and memory in the domain of legal psychology would lead
one to believe that the memory-undermining effects of alco-
hol on, for example, identications are limited (e.g. Harvey
et al., 2013). We examined how alcohol affects free and cued
recall at immediate and follow-up tests. Based on the well-
established observation that alcohol intoxication impairs
consolidation (Ray & Bates, 2006; Söderlund et al., 2005),
we expected memory of the mock crime details to be im-
paired, even at the follow-up test when participants were so-
ber again, and particularly so in participants who had
previously been highly intoxicated. By and large, this was
borne out by our data. To begin with, and in line with previ-
ous ndings (e.g. Read et al., 1992; van Oorsouw &
Merckelbach, 2012), alcohol intoxication was associated
with lower levels of correct recall, although this effect was
more straightforward for free than for cued recall. An excep-
tion to this pattern was the error rate for action details in the
cued recall that was higher for intoxicated than for sober
people.
Second, the memory-undermining effect increased with
higher levels of intoxication. Thus, in accordance with previous
research (e.g. Perry et al., 2006), we found a doseresponse
relationship. Third, the memory-undermining effect emerged
when participants were tested immediately (i.e. when in the
same state as while encoding) and persisted when sober
again. Last, higher levels of intoxication were associated
with a stronger tendency to go along with misleading ques-
tions (i.e. yielding) during both test sessions. This effect was
largely mediated by less complete recall, a pattern that ts
nicely with the idea of discrepancy detection (e.g. Peterson
et al., 1990; Schooler & Loftus, 1986) and the work of
Nash and Takarangi (2011).
As was the case in previous studies (e.g. Van Oorsouw &
Merckelbach, 2012), intoxicated participants reported fewer
correct details about the mock crime as compared with sober
participants at both test sessions. Importantly, the
undermining effect of intoxication was also evident when
we looked specically at memory for the enacted event
(i.e. stealing the money). Apparently, and in contrast to the
idea that memory traces for enacted events are more robust
against intoxication because they are better consolidated
(Engelkamp, 1995), alcohol impairs consolidation of mem-
ory traces regardless of whether or not the event is enacted.
Furthermore, the lost material cannot be readily retrieved
either when intoxicated or when sober again. We found free
recall to be already impaired at moderate levels of intoxica-
tion, but the effects were more straightforward when
intoxication exceeded a BAC of 0.10%. That intoxication
impaired free recall more than cued recall is in line with pre-
vious studies that found recognition memoryfor example,
identication in line-upsto be relative robust against at
least moderate levels of intoxication (Hagsand et al.,
2013b; Harvey et al., 2013).
One could argue that our ndings are of little practical
relevance because they relied on an articial mock crime
procedure. For example, one could question whether our
participants performed to the best of their abilities. However,
we found that participants were able to identify with the
main character.
7
Furthermore, they had no motive to
underperform, nor do we have reasons to assume that their
memory performance was shaped by demand characteristics.
After all, for a naïve participant, it is difcult to anticipate
what a discrepancy-detection-like pattern of performance
looks like. Thus, we believe that our ndings bear relevance
to the practical context of intoxicated defendants and wit-
nesses. Is it better to interrogate such a defendant or witness
immediately or wait until he or she is sober again? Police of-
cers regularly interview a suspect or witness while he or she
is still intoxicated, and also hold the belief that more critical
information is disclosed during an immediate interrogation
(Evans et al., 2009; van Oorsouw et al., 2013). The present
ndings demonstrate that during the second (sober) test, all
participants were better at a free recall test of the enacted part
of the mock crime as compared with the rst test. In addition,
only participants who had initially been severely intoxicated
demonstrated an improvement in cued recall memory during
the sober test. Given this signicant increase in correct re-
call, police ofcers are well advised to have the suspect or
witness sober up before questioning.
One explanation for the increase in recall of action details
over sessions might be reminiscence. Reminiscence refers to
the phenomenon that repeated testing elicits memory details
that were inaccessible during a previous test (Kelley &
Nairne, 2003; Odinot, Wolters, & Van Giezen, 2013; Otani,
Von Glahn, Goenert, Migita, & Widner, 2009). One reason
why we obtained a reminiscence pattern for free recall of
action elements in all participants might be that during the
second session, testing conditions were more favourable
(i.e. quiet environment and testing during the day) as com-
pared with the rst session (noisy bar and testing late at
night). However, the reminiscence pattern was only apparent
for free recall and action elements. Most importantly, ini-
tially intoxicated groups recalled overall fewer items on both
sessions compared with sober participants.
The present ndings lend support to the idea that poor
memory makes it difcult to detect discrepancies between
misleading information and what really happened. This ex-
plains why high levels of intoxication (i.e. BAC above
0.11%) increased the tendency to go along with misleading
information (i.e. yielding). In comparison with sober partici-
pants, severely intoxicated participants were more likely to
7
Although one could argue, of course, that these self-reports were less cred-
ible owing to intoxication.
Table 3. Summary of backwards linear regressions, with yield for
sessions 1 and 2 as dependent variable and BAC, FRStory, FRAct,
cued recall story, and cued recall actions for sessions 1 and 2 as in-
dependent variables
BSEβtp
Yield 1
FRStory1 0.29 0.06 0.48 4.39 0.000
Yield 2
FRStory1 0.25 0.07 0.39 3.36 0.001
FRAct1 0.22 0.09 0.28 2.46 0.017
BAC, blood alcohol concentration; FRStory, free recall story; FRAct, free
recall actions.
Intoxication, memory, and suggestibility 499
Copyright © 2015 John Wiley & Sons, Ltd. Appl. Cognit. Psychol. 29: 493501 (2015)
opt for one of two false alternatives, or to endorse a sug-
gested event. Severely intoxicated participants displayed this
tendency both when questioned immediately as well as when
sober again. According to the principle of discrepancy detec-
tion, poor memory for an event makes it difcult for individ-
uals to detect discrepancies between what actually happened
and what is only suggested (Peterson et al., 1990; Schooler &
Loftus, 1986). We believe that this principle helps to under-
stand the pattern found in the current study: Lacking specic
and detailed memories of an event due to impaired encoding
makes intoxicated participants more prone to go along with
misleading questions. Because raised suggestibility levels
were only evident for severe and not moderate intoxication,
one could speculate that suggestibility increases merely when
correct recall is compromised to a considerable extent.
We found that it was the tendency to go along with
leading questions rather than the tendency to change answers
after negative feedback (shift) that was affected by higher
levels of intoxication during encoding. This is in accordance
with the Santtila et al. (1999) study, which also noted that
intoxication was not related to an increased propensity to
change answers after receiving negative feedback. Appar-
ently, yielding and shifting are two distinct types of suggest-
ibility that are not affected by intoxication in a similar way.
We would argue that the memory-undermining effect of
intoxication and its inference with discrepancy detection pro-
motes yield suggestibility (i.e. acceptance of misinforma-
tion), while the anxiolytic properties of alcohol work against
shift suggestibility (i.e. acceptance of misinformation under
the pressure of negative feedback).
One limitation of our study was that the second test
session was conducted over the telephone. This may have
reduced participantsanxiety in comparison with the rst
session. The decrease in shift scores over sessions seems to
support this interpretation. Unfortunately, we did not ask
participants how anxious they felt. The links between intox-
ication, anxiety, and suggestibility clearly warrants further
research. What can be said with some condence on the
basis of the current ndings, however, is that poor memory
mediates the increased tendency to go along with leading
questions, especially when participants are immediately
questioned in a misleading way.
Another limitation of our study is the repeated testing de-
sign that we employed. One could speculate that repetition of
the same memory test within a timeframe of a few days in
sobersober versus intoxicatedsober participants contrib-
uted to articial group differences (e.g. sober participants
who feel familiar with the test vs. previously intoxicated par-
ticipants who feel less familiar with it). As mentioned earlier,
reminiscence in free recall of action details was demon-
strated for all groups, indicating some benecial effects of
repeated testing in all participants. Yet, only previously se-
verely intoxicated participants exhibited an increase over
sessions in cued recall, perhaps reecting a regression to
the mean. Nevertheless, overall, previously intoxicated par-
ticipants performed signicantly worse than control partici-
pants. Our point is that these ndings cannot be explained
solely in terms of practice effects. More generally, some
authors have argued that we should not exaggerate the effects
of repeated testing (e.g. Greiffenstein, 2009). Still, a design
including delayed-test only groups would, of course, be more
ideal and future studies may want to include such groups in
order to exclude practice effects.
Another limitation that is typical for this sort of eld study
is that it lacks control over potential confounders such as
health factors and the amount of alcohol participants con-
sume after the experimenters leave the scene. However, such
confounders will introduce noise, and it is likely that they lead
to an underestimation of intoxication-memory effects. Another
factor that could have obscured the results is fatigue. That is,
some participants were tested early in the evening and others
in the middle of the night. But again, time of testing will have
introduced error noise and therefore will have led to underesti-
mation of effects.
8
The same is true for the relatively short
interval between mock crime and rst interview. Of course, a
police interrogation is unlikely to be conducted some 10 minutes
after the crime took place. But with a longer time intervalsay
3060 minutesand keeping the slow breakdown of alcohol in
mind (0.02% per hour), it is plausible that stronger memory-
undermining effects of intoxication will occur.
Despite these limitations, our results indicate that it could
be benecial to wait with interrogating an intoxicated sus-
pect or witness until he or she has sobered up. Evans and col-
leagues (2009) found that intoxicated suspects are more
likely to waive their Miranda rights and incriminate them-
selves. These are alarming observations considering that
we found intoxication to be associated with poorer memory
and heightened suggestibility.
Criminal courts frequently face complications when defen-
dants or witnesses have been intoxicated. In such cases, expert
witnesses are often appointed to examine, for example, claims
of amnesia. Given the limited number of studies in this do-
main, we need more research on the links between alcohol,
memory, and suggestibility so as to be better able to inform tri-
ers of fact in intoxication cases. The present study is one stepin
that direction. It clearly shows that intoxication interferes with
memory completeness in a dose-dependent manner.
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Intoxication, memory, and suggestibility 501
Copyright © 2015 John Wiley & Sons, Ltd. Appl. Cognit. Psychol. 29: 493501 (2015)
... A final possibility is that people who are alcohol intoxicated during sexual encounters will be more likely to erroneously remember consensual sexual activity as non-consensual. Several studies have examined the impact of alcohol on suggestibility (Schreiber Compo et al., 2012;van Oorsouw et al., 2015van Oorsouw et al., , 2019Gawrylowicz et al., 2017;Evans et al., 2019). Overall, the findings suggest that mere exposure to suggestive information is not sufficient for participants to incorporate the misleading information into memory (Schreiber Compo et al., 2012), including in hypothetical rape encounters . ...
... Overall, the findings suggest that mere exposure to suggestive information is not sufficient for participants to incorporate the misleading information into memory (Schreiber Compo et al., 2012), including in hypothetical rape encounters . However, alcohol intoxication during encoding later renders individuals more susceptible to reporting misinformation if they are repeatedly questioned using inappropriate techniques (e.g., suggestive follow up questions, see van Oorsouw et al., 2015). Nevertheless, perhaps women are more prone to memory distortion when remembering what sexual activities they consented to while alcohol intoxicated, owing to stereotypes about women, alcohol, and sexual availability (see Davis and Loftus, 2015). ...
... One limitation is that the participants in this study were of course not exposed to the same degree of trauma as a victim of rape would be. Another limitation is that the alcohol intoxication levels experienced by participants are low to moderate in comparison to alcohol intoxication levels encountered in the field and in intoxicated victims of rape encountered by the police (see Evans et al., 2009;van Oorsouw et al., 2015). Further research is needed under higher levels of intoxication The confidence-accuracy relationship as a function of beverage (top panel) and expectancy (bottom panel). ...
Article
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Objective To test whether acute alcohol intoxication and alcohol expectancy affects how accurately women remember consensual and non-consensual sexual activity that occurred during an interactive hypothetical dating scenario. Design A balanced placebo randomized study that varied alcohol dose (mean Breath Alcohol Content; BrAC = 0.06%) and alcohol expectancy prior to participants encoding a hypothetical interactive rape scenario was implemented. Participants could elect to consent to sexual activity with a male partner in the hypothetical scenario. If they stopped consenting, non-consensual sexual intercourse (i.e., rape) was described. Seven days later, participants’ memory for consensual and non-consensual sexual activity in the scenario was tested. Main outcome measures Memory accuracy, confidence, and feelings of intoxication. Results A total of 90 females ( M age = 20.5, SD = 2.2) were tested regarding their memory accuracy for the consensual and non-consensual sexual activities in the scenario. A multi-level logistic regression predicting memory accuracy for the perpetrator’s behaviors during the rape indicated no effect of alcohol intoxication. However, a main effect of alcohol expectancy was found, whereby participants who expected to consume alcohol, compared to those who did not, recalled the perpetrator’s behaviors during the rape more accurately. A second regression predicting memory accuracy for consensual sexual activity found no main effects for alcohol intoxication or alcohol expectancy. Participants recalled consensual sexual activity with a high degree of accuracy. Calibration analyses indicated that accuracy increased with confidence level, regardless of intoxication level or alcohol expectancy condition, but that women tended to be overconfident in general. Conclusion This study provides an important test of how accurately women remember consensual and non-consensual sexual activities. The accuracy of this information is important for forensic medical examinations and police investigations following an allegation of sexual assault. Increased memory accuracy was found for offence details when participants expected to consume alcohol, suggesting there may be important differences in attentional processes (e.g., hypervigilance) depending on whether threat is present. Further research is necessary to investigate memory for sexual violence in real-world settings and to test methods for ascertaining the most complete and reliable accounts.
... In line with lab research, field studies employing higher BACs (> 0.09%) showed that accounts by severely intoxicated indivdiuals are less complete than those produced by sober ones (Altman et al. 2018;Altman et al. 2018;Crossland et al. 2016). In contrast to low to moderate intoxication levels, high levels may also negatively impact recall accuracy, that is, as alcohol levels increase, the proportion of accurate details recalled decreases (Altman et al. 2018;Van Oorsouw et al. 2015) and the number of 'don't know' responses increases (Crossland et al. 2016). Similarly, fieldwork testing immediate and delayed suggestibility showed that as intoxication levels increase, so does one's willingness to go along with incorrect suggestions (Van Oorsouw et al. 2015;. ...
... In contrast to low to moderate intoxication levels, high levels may also negatively impact recall accuracy, that is, as alcohol levels increase, the proportion of accurate details recalled decreases (Altman et al. 2018;Van Oorsouw et al. 2015) and the number of 'don't know' responses increases (Crossland et al. 2016). Similarly, fieldwork testing immediate and delayed suggestibility showed that as intoxication levels increase, so does one's willingness to go along with incorrect suggestions (Van Oorsouw et al. 2015;. Together, this work suggests that lower doses of acohol may reduce the recollection of details without negatively affecting recall accuracy or one's susceptibility to misinformation. ...
... Most work examining how alcohol affects the tendency to report misinformation has used leading questions (Van Oorsouw et al. 2015; or false information incorporated into written or oral accounts Schreiber Compo et al. 2012;Thorley & Christiansen 2018). Work by Evans et al. (2019) incorporated written misinformation in the form of a forced-choice recognition test that contained answers that had already been circled, seemingly by a previous participant. ...
Article
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Rationale Witnesses who discuss a crime together may report details that they did not see themselves but heard about from their co-witness. Co-witness information may have beneficial and harmful effects on memory accuracy depending on whether the information was correct or incorrect. Objectives Given the prevalence of intoxicated witnesses, it is imperative to understand how alcohol influences this effect. Methods The present study asked pubgoers (n = 67) at varying levels of intoxication to recall a mock crime video after having also watched a video witness statement containing both correct and false information. Results Increased intoxication was associated with decreased confidence, completeness and accuracy, but no increased tendency to report false information. Exposure to incorrect post-event information (PEI) can lead to the incorporation of incorrect information, whereas exposure to correct PEI increased accuracy, regardless of individuals’ alcohol intoxication status. Conclusions Thus, whilst discussion and intoxication can negatively impact eyewitness memory, discussion may also have benefits for both sober and intoxicated witnesses.
... In an experimental study with mock suspects under the influence of alcohol, intoxication impaired the recall of a mock criminal event, especially for information about people (Read et al., 1992); recall of the mock-suspects' own actions was also impaired. In a quasi-experimental study in real bars by van Oorsouw et al. (2015), alcohol impaired memory in participants carrying out a mock crime, both during an immediate interrogation and later when participants were sober. Furthermore, an experimental lab study examined alcoholintoxicated participants' decision-making skills on whether they would report a transgression carried out by themselves or someone else. ...
... Examining the impact of breath alcohol level on suspects' cognition and decision-making is important, in light of recent findings that low to moderate alcohol doses do not affect suggestibility (Mindthoff et al., 2021) or the risk of disclosing transgressions (Mindthoff et al., 2019). Some field studies however suggest that higher intoxication levels may impair cognition among mock suspects (e.g., van Oorsouw et al., 2015). ...
Article
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Background: Low-stakes crimes related to alcohol and/or drugs are common around the world, but research is lacking on police–suspect interactions of such crimes. A large proportion of these suspects are intoxicated during interrogations, and many may have substance use disorder, making them potentially vulnerable to interrogative pressure. Methods: To address this lack of knowledge, the taxonomy of interrogation methods framework (i.e., 60+ interrogation techniques classified into five domains) and a common classification of question types (appropriate vs. inappropriate) were applied in the coding of written police interrogations. Two archival studies, one pilot (Study 1, N = 39) and one main study (Study 2, N = 97) analyzed police interrogations with suspects of alcohol- and drug-related crimes in Sweden. Results: For both Study 1 and 2, suspects showed signs of alcohol and/or drug intoxication, hangover or withdrawal in more than 50% of all interrogations. In Study 2, additional coding indicated that suspects displayed signs of substance use disorder in 57% of the interrogations. The main results from both studies revealed a large number of direct questions asked by the police across all interrogations, and relatively little use of the strategic interrogation techniques from the taxonomy of interrogation methods framework. In fact, when it came to interrogation techniques, law enforcement used more confrontational techniques in their interactions with intoxicated suspects compared to sober suspects. Furthermore, suspects displaying signs of substance use disorder were significantly more cooperative and prone to confess than suspects without indicators of substance use disorder. Conclusion: As the first novel study on low-stakes crime interrogations related to alcohol and/or drugs, the present study provides useful information about current Swedish interrogation practices and areas for improvement. The study results indicate that suspects displaying signs of intoxication or substance use disorder may be more vulnerable during police interrogations. This may in turn have the potential to inform the development of new interrogation policies. Due to the novelty of this research, more studies are needed, both on a national and international level, to examine interrogations in low-stakes crimes further.
... In an experimental study with mock suspects under the influence of alcohol, intoxication impaired the recall of a mock criminal event, especially for information about people (Read et al., 1992); recall of the mock-suspects' own actions was also impaired. In a quasi-experimental study in real bars by van Oorsouw et al. (2015), alcohol impaired memory in participants carrying out a mock crime, both during an immediate interrogation and later when participants were sober. Furthermore, an experimental lab study examined alcoholintoxicated participants' decision-making skills on whether they would report a transgression carried out by themselves or someone else. ...
... Examining the impact of breath alcohol level on suspects' cognition and decision-making is important, in light of recent findings that low to moderate alcohol doses do not affect suggestibility (Mindthoff et al., 2021) or the risk of disclosing transgressions (Mindthoff et al., 2019). Some field studies however suggest that higher intoxication levels may impair cognition among mock suspects (e.g., van Oorsouw et al., 2015). ...
Article
Full-text available
Background Low-stakes crimes related to alcohol and/or drugs are common around the world, but research is lacking on police–suspect interactions of such crimes. A large proportion of these suspects are intoxicated during interrogations, and many may have substance use disorder, making them potentially vulnerable to interrogative pressure.Methods To address this lack of knowledge, the taxonomy of interrogation methods framework (i.e., 60+ interrogation techniques classified into five domains) and a common classification of question types (appropriate vs. inappropriate) were applied in the coding of written police interrogations. Two archival studies, one pilot (Study 1, N = 39) and one main study (Study 2, N = 97) analyzed police interrogations with suspects of alcohol- and drug-related crimes in Sweden.ResultsFor both Study 1 and 2, suspects showed signs of alcohol and/or drug intoxication, hangover or withdrawal in more than 50% of all interrogations. In Study 2, additional coding indicated that suspects displayed signs of substance use disorder in 57% of the interrogations. The main results from both studies revealed a large number of direct questions asked by the police across all interrogations, and relatively little use of the strategic interrogation techniques from the taxonomy of interrogation methods framework. In fact, when it came to interrogation techniques, law enforcement used more confrontational techniques in their interactions with intoxicated suspects compared to sober suspects. Furthermore, suspects displaying signs of substance use disorder were significantly more cooperative and prone to confess than suspects without indicators of substance use disorder.Conclusion As the first novel study on low-stakes crime interrogations related to alcohol and/or drugs, the present study provides useful information about current Swedish interrogation practices and areas for improvement. The study results indicate that suspects displaying signs of intoxication or substance use disorder may be more vulnerable during police interrogations. This may in turn have the potential to inform the development of new interrogation policies. Due to the novelty of this research, more studies are needed, both on a national and international level, to examine interrogations in low-stakes crimes further.
... Alcohol intoxication impairs the encoding and consolidation of memories and therefore, affects the information they are able to provide. Field studies on the effects of alcohol on memory showed that, when again sober, individuals who had been moderately to severely intoxicated during encoding were less complete in their memory reports, remembering fewer correct details than sober individuals (Van Oorsouw & Merckelbach, 2012;Van Oorsouw et al., 2015). So, if an eyewitness was under the influence of alcohol while witnessing a crime, they may report less information to the police a few days later compared to an eyewitness who was sober during the crime. ...
... H owever, sometimes eyewitnesses are interviewed immediately, while they are still intoxicated. In this case, intoxicated individuals also have a tendency to report fewer correct details (Van Oorsouw et al., 2015). Furthermore, there seems to be a negative relationship between level of alcohol intoxication and memory performance: the more intoxicated you are, the worse your memory for that event is. ...
Chapter
The chapter discusses some of the many factors that affect eyewitness testimony.
... At moderate doses there also appears to be a benefit of using free recall formats over cued recall questions to reduce the reporting of incorrect details (Compo et al., 2012;Schreiber Compo et al., 2017). At higher doses, the quality of memory reports starts to decline (Altman, et al., 2018) and witnesses may become more prone to suggestibility (Van Oorsouw et al., 2015, although these findings are equivocal (Crossland et al., 2016). It appears, therefore, that while there is evidence that intoxication impairs the quantity of memory recall, the quality of memory reports is maintained, at least at moderate doses. ...
Article
Full-text available
Memory conformity may occur when a person’s belief in another’s memory report outweighs their belief in their own. Witnesses might be less likely to believe and therefore take on false information from intoxicated co-witnesses, due to the common belief that alcohol impairs memory performance. This paper presents an online study in which participants (n = 281) watched a video of a mock crime taking place outside a pub that included a witness either visibly consuming wine or a soft drink. Participants then read a statement from the witness that varied in the number of false details it contained before being asked to recall the crime. We found that the intoxicated witness was regarded as significantly less credible, but participants were not less likely to report misinformation from them. This suggests that intoxication status impacts one’s perception of how credible a source is, but not one’s ability to reject false suggestions from this source. Our findings reinforce the importance of minimizing co-witness discussion prior to interview, and not to assume that people automatically (correctly or not) discount information provided by intoxicated co-witnesses.
... The best-studied substance in the legal context is alcohol, for which studies using misinformation and suggestibility methods have yielded mixed findings (Flowe & Schreiber Compo, 2021;Kloft et al., 2021;Mindthoff et al., 2021). At low-to-moderate levels (0.04%-0.14%), alcohol did not impact the misinformation effect (Flowe et al., 2019;Schreiber Compo et al., 2012), but suggestibility was elevated at high alcohol levels (0.10%-0.25%; van Oorsouw et al., 2015van Oorsouw et al., , 2019. However, moderate alcohol levels (0.08%) also appear to affect suggestibility when a delay is interposed between the event during intoxication and its retrieval attempt (Evans et al., 2019). ...
... Evans et al., 2009), and in line with research suggesting increased cognitive impairment in witnesses' memory for events at higher BrAC levels (e.g., Altman et al., 2019), individuals' comprehension of their rights may further deteriorate with greater intoxication. Thus, we encourage researchers to test Miranda comprehension in the field with highly intoxicated individuals (see Altman et al., 2019, andVan Oorsouw et al., 2015, for examples of field studies with highly intoxicated participants). We expect that complementing the present findings with field research will offer researchers, practitioners, and policy makers a more comprehensive understanding of alcohol intoxication's impact on Miranda comprehension. ...
Article
Full-text available
Objective: Law enforcement officers often encounter alcohol-intoxicated suspects, suggesting that many suspects are presented with the challenge of grasping the meaning and significance of their Miranda rights while intoxicated. Such comprehension is crucial, given that Miranda is intended to minimize the likelihood of coercive interrogations resulting in self-incrimination and protect suspects' constitutional rights. Yet, the effects of alcohol on individuals' ability to understand and appreciate their Miranda rights remain unknown-a gap that the present study sought to address. Hypotheses: Informed by alcohol myopia theory (AMT), we predicted that intoxicated individuals would demonstrate impaired Miranda comprehension compared to sober individuals and those who believed they were intoxicated (but were in fact not; i.e., placebo participants). Method: After health screenings, participants completed the Wechsler Abbreviated Scale of Intelligence-Second Edition verbal subtests, rendering a Verbal Comprehension Index (VCI) score. We randomly assigned participants to consume alcohol (n = 51; mean breath alcohol concentration [BrAC] = 0.07%), a placebo condition (n = 44; BrAC = 0.00%), or a sober control condition (n = 41; BrAC = 0.00%). All participants (N = 136) completed the Miranda Rights Comprehension Instruments (MRCI), which measured participants' understanding of the Miranda warnings, recognition of the warnings, appreciation of their rights in interrogation and court settings, and understanding of Miranda-related vocabulary. Results: We found a significant effect of intoxication condition on participants' understanding of Miranda warnings (η²p = .14) and Miranda-related vocabulary (η²p = .05) when controlling for VCI scores. Specifically, intoxicated participants received lower scores for understanding of warnings compared to sober and placebo participants, and lower scores for understanding of Miranda vocabulary compared to sober participants. Alcohol did not significantly impact Miranda rights recognition or appreciation. Conclusions: Alcohol intoxication may detrimentally impact some facets of Miranda comprehension. Thus, it is important that law enforcement consider refraining from questioning intoxicated suspects. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
Article
Eyewitnesses play a significant role in criminal investigations and legal processes worldwide. Just like any other type of forensic evidence, eyewitness evidence has a margin of error. These errors, caused by numerous factors, affect the validity of eyewitness testimony. Some factors emerge at the moment of witnessing, while others occur afterwards. One of the main challenges for legal practitioners is to base their interviewing practices and decision-making on solid scientific evidence. Insight into the cognitive processes of a witness is vital for understanding why people make mistakes. Therefore, our chapter starts with a brief explanation of the organization of memory. Then, using a realistic example, we describe several variables that affect witness testimony, while loosely following the three stages of memory: witnessing, retention and retrieval. Next, we discuss various factors affecting judges’ and jurors’ assessments of witness testimony, which in turn influence legal decision-making. Finally, we summarize our findings and make some concluding remarks.
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Alcohol affects memory in many, and mostly negative, ways. This is a problem in legal contexts as many witnesses are alcohol intoxicated when taking part of the critical event. However, research is sparse regarding how, and under what circumstances, the reports of alcohol intoxicated witnesses differ from those of sober witnesses. This study investigated whether alcohol intoxicated and sober eyewitnesses differ regarding completeness, accuracy, and type of information reported, as well as whether gender influenced these variables. Eighty-seven healthy men (n = 44) and women (n = 43) received either an alcoholic beverage (0.7 g/kg) or a control (juice) in a laboratory setting before viewing a film picturing intimate partner violence. Ten minutes after viewing the film, they were interviewed. Reports by alcohol intoxicated women were less complete, but as accurate, as sober women's. In contrast, intoxicated and sober men did not differ regarding completeness or accuracy. Furthermore, compared with sober women, intoxicated women reported fewer actions but no difference was found between the groups regarding reported objects. At this moderate dose, alcohol affected women's reports more than men's, which may be because alcohol affects attention and memory consolidation more clearly at a lower dose for women than for men.
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Although alcohol intoxicated eyewitnesses are common, there are only a few studies in the area. The aim of the current study is to investigate how different doses of alcohol affect eyewitness lineup identification performance. The participants (N = 123) were randomly assigned to a 3 [Beverage: control (0.0 g/kg ethanol) vs. lower (0.4 g/kg ethanol) vs. higher alcohol dose (0.7 g/kg ethanol)] X 2 (Lineup: target-present vs. target-absent) between-subject design. Participants consumed two glasses of beverage at an even pace for 15 minutes. Five minutes after consumption the participants witnessed a film depicting a staged kidnapping. Seven days later, the participants returned to the laboratory and were asked to identify the culprit in a simultaneous lineup. The result showed that overall, the participants performed better than chance however, their lineup performance was poor. There were no significant effects of alcohol intoxication with respect to performance, neither in target-present nor target-absent lineups. The study’s results suggest that eyewitnesses who have consumed a lower (0.4 g/kg ethanol) or a higher (0.7 g/kg ethanol) dose of alcohol perform at the same level as sober eyewitnesses in a lineup. The results are discussed in relation to the alcohol myopia theory and suggestions for future research are made.
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In legal practice, both confidence and consistency of the testimony of eyewitnesses are often used as indicators for accuracy, but their usefulness has been questioned. The present study was designed to determine the relationship between accuracy, confidence and consistency in episodic memory. After viewing a video of a complex series of events, one group of participants was given an initial cued recall test after one week, and repeated recall tests after three and five weeks. A second group of participants was tested after three and five weeks, and a third group was tested only once after five weeks. Accuracy and confidence (at least for incorrect answers) decreased with longer initial retention intervals, but there was no decrease in either accuracy or confidence when recall was repeated. Repeated testing also did not lead to confidence inflation. Correlations between accuracy, confidence and consistency varied from medium to large. Inconsistencies were mainly caused by forgetting and reminiscence. These inconsistencies were recalled almost as accurately as consistently recalled information.
Chapter
There is a growing theoretical and practical interest in the topic of metacognition; how we monitor and control our mental processes. Applied Metacognition provides a coherent and up-to-date overview of the relation between theories in metacognition and their application in real-world situations. As well as a theoretical overview, there are substantive chapters covering metacognition in three areas of application: metacognition in education, metacognition in everyday life memory and metacognition in different populations. A diverse range of topics are covered such as how we judge our own learning, why we create false beliefs about our past, how children learn to monitor and control their memory, how well eyewitnesses can judge the accuracy of their own memories and how memory judgements change across the lifespan. The book has contributions from many of the leading researchers in metacognition from around the world.
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Hypermnesia is a phenomenon in which memory performance improves across repeated tests even though no new exposure to the study material occurs between tests. Hypermnesia is a combined effect of reminiscence (item gains) and intertest forgetting (item losses). When reminiscence exceeds intertest forgetting, memory performance increases across repeated tests to produce hypermnesia. In this chapter, we review basic findings and theories and explore possible applications of hypermnesia. Based upon the review, we propose the following. In education, repeated testing can be used to maximize students' recall and promote long-term retention. In forensic settings, repeated testing can be used to uncover new information but repeated testing can also increase incorrect recall and distort source information. For older adults, we propose that a decline in reminiscence may indicate abnormal aging process. In clinical psychology, hypnotic hypermnesia is not a special case of hypermnesia but hypnosis can increase false confidence by highly hypnotizable individuals. Finally, we propose that hypermnesia is a normal memory phenomenon that should be included in a standardized memory scale to measure the level of memory functioning. We conclude the chapter by suggesting that the practitioners of repeated testing must be aware of the benefits and costs of repeating a test.
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One week after committing a simulated robbery while intoxicated or sober, each of 142 male university students recalled the event within a "cognitive interview." In Exp 1, alcohol consumption reduced the accuracy of recall of information about persons. In Exp 2, person identification (ID) suffered following the consumption of alcohol, but only when arousal was low. Higher levels of arousal appeared to minimize the negative impact of alcohol on encoding and recall. Alcohol impaired Ss' recollections of what they did. Data from Exp 2 supported the hypothesis that increased arousal reduces attention to peripheral sources of information. A similar hypothesis about the effects of alcohol received only mixed support because the Ss' behaviors reflected the "alcohol myopia," but their IDs of target persons did not. Manipulations at the time of retrieval of Ss' beliefs about how much alcohol had been consumed also altered accuracy of recall. (PsycINFO Database Record (c) 2014 APA, all rights reserved)
Article
Alcohol is a contributing factor in many crimes, yet little is known of its effects on eyewitness memory and face identification. Some authors suggest that intoxication impairs attention and memory, particularly for peripheral scene information, but the data supporting this claim are limited. The present study therefore sought to determine whether (i) intoxicated participants spend less time fixating on peripheral regions of crime images than sober counterparts, (ii) whether less information is recognised from image regions receiving fewer gaze fixations and (iii) whether intoxicated participants are less able to identify the perpetrator of a crime than sober participants. Contrary to expectations, participants' ability to explore and subsequently recognise the contents of the stimulus scenes was unaffected by alcohol, suggesting that the relationship between intoxication, attention and eyewitness memory requires closer scrutiny. Copyright © 2013 John Wiley & Sons, Ltd.