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The effect of cognitive load on nonverbal behavior in the cognitive interview for suspects
Personality and Individual Differences 130 (2018) 51–58
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The effect of cognitive load on nonverbal behavior in the cognitive interview for suspects
T
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P. Frosina, M. Logue, A. Book , T. Huizinga, S. Amos, S. Stark Brock University, St. Catharines, ON, Canada
A R T I C LE I N FO
A B S T R A C T
Keywords: Interrogation Nonverbal cues Cognitive interview Cognitive load Psychopathy
We investigated whether cognitive load results in changes to nonverbal behavior in the context of interrogation, and whether psychopathic traits affected this relationship. Cognitive load was implemented by using the cognitive interview for suspects (CIS). Onehundred- and-fifty undergraduate students were assigned to one of two conditions: 1) a true event, where they played a game with a confederate, and money went missing from a wallet in the room, or 2) a false-alibi condition, where they read a scenario similar to the true event (in order to create a feasible alibi), and were instructed to steal $10 from the wallet. Blinking, hand gestures, trunk movements, and direct eye gaze were coded at each point in the CIS. Regardless of condition, the increase in cognitive load had the effect of increasing blinking and decreasing hand gestures and direct eye gaze. There were significant interactions between CIS stage and experimental condition for blinks and hand gestures, where people in the false alibi condition had a sharper increase in blinking, and decrease in hand gestures when cognitive load was introduced. Psychopathic traits did not affect the utility of above cues, but change in trunk movements was positively correlated with psychopathy in the false alibi condition.
1. Introduction Police are trained to use nonverbal cues to detect deception (Bull, 1989), but their accuracy hovers around chance, regardless of experience (Vrij, 2000, 2004). In fact, training in traditional interrogation techniques, (i.e. Reid technique) actually result in decreased accuracy (Kassin & Fong, 1999). Cues used include gaze-aversion, an increase in hand/ft movements, and an increase in fidgeting, which are thought to increase due to heightened anxiety or nervousness when being deceptive. The most commonly stereotyped cue is gaze-aversion (e.g. Akehurst, Kohnken, Vrij, & Bull, 1996) which actually has little association with deception, according to a comprehensive meta-analysis (DePaulo et al., 2003). In fact, a recent study suggests that deception is characterized by increased deliberate eye-contact (Mann et al., 2012). DePaulo et al.'s meta-analysis did not find any cues that reliably discriminate between lies/truths. It should be noted that most studies that have been conducted have used student samples in a laboratory context, and only three used forensic samples. In one study of actual interrogations, Mann, Vrij, and Bull (2002) found that liars blinked less, but no relationship was observed for gaze-aversion, illustrators, or hand/arm movements. Approximately half of the sample showed gazeaversion during deception, while the other half showed less gazeaversion, suggesting that there may be individual differences in how
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deception is expressed in nonverbal behavior. Another possible reason for mixed findings is that deception causes changes in nonverbal behavior that may differ between individuals. Thus, it would be important to examine these cues in relation to baseline behaviors. Previous research does suggest that prior familiarity with an individual increases accuracy of deception detection (e.g. DePaulo, 1994). We can exaggerate differences between liars and truth tellers by increasing cognitive load (i.e. making deception more cognitively demanding; Vrij et al., 2008). Deception is already more cognitively demanding than truth telling for a number of reasons, as discussed by Vrij et al. For example, the deceiver has to formulate a story and remind themselves of the details of the story (DePaulo et al., 2003) and deception requires a good deal of self-monitoring in order to appear to be honest (DePaulo & Kirkendol, 1989). Further, the deceiver must invest energy into monitoring the interviewer to determine whether the lie is being believed (Buller & Burgoon, 1996). The deceiver also has to attempt to suppress the truth (Spence et al., 2001). Overall, then, deception requires deliberate mental effort that is unnecessary when telling the truth (Gilbert, 1991). Because deception is cognitively demanding, some researchers have suggested that the nonverbal cues that should be associated with deception are those that are associated with increased cognitive load. Unlike the nonverbal cues associated with anxiety (e.g. increased
Corresponding author. E-mail addresses: [email protected] (P. Frosina), [email protected] (A. Book).
https://doi.org/10.1016/j.paid.2018.03.012 Received 15 August 2017; Received in revised form 23 February 2018; Accepted 7 March 2018 0191-8869/ © 2018 Elsevier Ltd. All rights reserved.
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blinking and gesturing; Vrij et al., 2008), cognitive load reduces fidgeting, gesturing, and blinking. This has led a number of researchers to suggest that these could be cues to deception, given its cognitive demands (e.g. Mann et al., 2002; Vrij & Mann, 2003). Vrij et al. (2008) attempted to enhance the differences between liars and truth tellers, having participants tell stories in reverse chronological order in an attempt to increase cognitive load. Participants were randomly assigned to a reverse order or chronological order condition. As expected, more verbal cues to deceit were observed in the reverse order condition, but, also, nonverbal behavior that is typically associated with anxiety increased, including blinking and hand/foot movements. While gaze-aversion was measured, no results were reported. These findings suggest that not only is telling stories in the reverse order more cognitively demanding, it may also increase anxiety, resulting in an increase in the nonverbal behavior associated with anxiety. Vrij et al. (2008) suggest that a cognitively demanding interview will be especially problematic for people attempting to be deceptive, as deception is cognitively demanding on its own. One interview that does increase cognitive load is the cognitive interview for suspects (CIS) developed by Geiselman (2012). The CIS increases cognitive load by asking the suspect to recount their story in different orders (e.g. backwards). The cognitive interview is an empirically validated method for interviewing witnesses and victims (reviewed by Geiselman, 2012), elicits more information (and more correct information), and has excellent reliability and validity (Kohnken, Milne, Memon, & Bull, 1999). As mentioned, this interview has recently been adapted for use with suspects (Geiselman, 2012). Not only does the CIS increase cognitive load, but also cues to deception can be examined at different points in the interview, allowing the interviewer to see changes in behavior as cognitive load increases. As suggested by Vrij et al. (2008), discrepancies in nonverbal behaviors should occur with the addition of cognitive load. Because some previous findings suggest that individual differences exist for some nonverbal cues (e.g. gaze aversion in the Mann et al., 2002), we sought to determine whether psychopathic traits, which include a tendency to make use of deception and manipulation (Hare, 2003) might influence the display of nonverbal cues during deception. As well, psychopaths are responsible for a disproportionate amount of crime (Quayle, 2008) and, thus, are overrepresented in the legal system (Hare, 2003). People with psychopathic traits do tend to utilize deception more often than other people (Seto, Khattar, Lalumiére, & Quinsey, 1997), and there is some evidence that they may be better at it than others (Billings, 2004; Book, Starzyk, Holden, Wasylkiw, & Edwards, 2006), although Klaver, Lee, Spidel, and Hart (2009) found that raters were better able to pick up on deception in psychopaths than in non-psychopaths, and Raskin and Hare (1978) did not find any differences in arousal during deception. Though findings are mixed, it is clear that deception detection is an important part of the interrogation process, and may be impacted by individual differences such as psychopathy (Klaver et al., 2009). Fitting with the idea that psychopaths have a dominant interpersonal style is Quayle's (2008) assertion that psychopathic suspects will try to charm and outwit the interrogator, including using distracting and dominant nonverbal behavior, such as using more hand gestures, moving towards the interviewer, and direct eye contact. While little research has been conducted looking at nonverbal behavior and deception in relation to psychopathy, a number of studies have examined their nonverbal behavior in interpersonal situations and interviews. In the only study to examine the relationship between nonverbal behaviors and deception in individuals with psychopathic traits, Klaver, Lee, and Hart (2007), asked inmates from a federal prison to tell a true story regarding their crime, and a false story about a crime they didn't commit. Regardless of condition, people scoring higher on psychopathy displayed more blinking and illustrators (Klaver et al.). The researchers suggested that the increase in blinking may serve to
help psychopaths manage the impression they give to the interviewer, however further research is needed to validate this claim. These findings contradict previous studies investigating blinking behavior in deceitful suspects (Mann et al., 2002; Vrij & Mann, 2001), and shed light of the possibility of interpersonal traits associated with psychopathy moderating nonverbal behaviors in deceptive psychopaths (Klaver et al.). With regard to the increase in illustrator usages, Klaver et al. touched on previous studies showing interpersonal characteristics of psychopathy being associated with an increase in hand gestures (Gillstrom & Hare, 1988; Rimé, Bouvy, Leborgne, & Rouillon, 1978). Research by Gillstrom and Hare (1988), examined hand gestures from videotaped interviews of individuals scoring high, medium and low on the PCL-R. Their results showed psychopaths to employ more hand gestures when compared to non-psychopaths. Specifically, people with psychopathic traits exhibited more beats (hand gestures that are unrelated to speech) compared to those scoring medium or low. It was also theorized that beats might be used to distract the interviewer and gain control over the interview itself (Gillstrom & Hare, 1988). The above findings highlight the need for research to examine factor scores of psychopathy with regards to differences in nonverbal behaviors during deception. The current study seeks to examine whether changes in nonverbal behaviors over the course of the CIS are consistent with either a) heightened anxiety (resulting in increased gesturing, gaze aversion, and blinking), b) increased cognitive load (resulting in decreases), or c) both. Because other studies have found that individual differences may be important (Mann et al., 2002), we also predicted that psychopathic traits may be related to changes in nonverbal cues when cognitive load is introduced. 2. Methods 2.1. Participants One-hundred-and-fifty undergraduate students participated (76 women; 74 men (Mage = 20.97; SD = 3.42)) and were randomly assigned to the truthful or false-alibi condition. The study was given approval to proceed by the university Research Ethics Board. 2.2. Measures 2.2.1. Psychopathic traits Psychopathic traits were assessed using the Self-Report Psychopathy Scale: Version III (SRP-III), which has demonstrated strong reliability (α = 0.88) in previous studies (Williams, Nathanson, & Paulhus, 2003). The SRP-III accommodates changes by Hare (2003) pertaining to the expansion of the PCL-R from a two to a four-facet structure examining Antisocial Behavior, Impulsive Thrill-Seeking, Interpersonal Manipulation and Cold Affect (Williams et al., 2003). The SRP-III measures components associated with Factor 1 and Factor 2 of the PCL-R and divides the acquired results into four facets: interpersonal manipulation, callous affect, erratic lifestyle and anti-social behaviors (Williams, Paulhus, & Hare, 2007). Each of these facets has shown to have construct validity with regards to self-reports of anti-social behaviors as well as personality characteristics (Williams et al., 2007), and has shown to be a valid and reliable measure of subclinical psychopathic traits (Williams et al., 2003). The measure consists of 64 items rated on a five-point scale with potential responses ranging from 1 (disagree strongly) to 5 (strongly agree). Internal consistencies in the present study support the reliability of the measure (alphas range from 0.75 to 0.83 for Interpersonal Manipulation, Callous Affect, Erratic Lifestyle, and Antisocial Behavior). 2.2.2. Nonverbal behaviors Nonverbal behaviors were coded employing techniques showing acceptable reliability in previous studies (e.g. Granhag & Stromwall, 52
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room before returning. The game continues until [research confederate] comes back into the lab and locates the wallet that is on the desk. This person opens the wallet, and claims that there is $10 missing.” “The wallet is sitting on the table in the corner of the room. Take the $10 out of the wallet. You will be interviewed by a separate person to determine whether you took the $10. If you convince the interviewer that you did not take the money, you will get to keep the $10.”
2002; Vrij, 1995). To establish interrater reliability, two raters coded the nonverbal behaviors for 10 randomly chosen participants. After we established that interrater reliability was acceptable, the raters each coded half of the remaining interviews. Nonverbal behaviors under investigation included blinking (frequency), beats (frequency), and trunk movements (frequency). Blinking, beats, and trunk movements were coded as frequency of the behavior per minute. Intraclass correlations (ICC's) were deemed acceptable (0.96, 0.83, and 0.71 for blinking, beats, and trunk movements, respectively), and the tw raters each coded half of the remaining participant videos. Direct eye gaze was coded according to the instructions for the interpersonal measure of psychopathy (IMP) (Kosson, Steuerwald, Forth, & Kirkhart, 1997). More specifically, a participant could be scored as 0 (indicating that the behavior was not exhibited at all), 1 (the behavior was somewhat evident), 2 (the behavior was very evident), or 3 (the behavior was exhibited consistently/frequently). The IMP has shown to have strong inter-rater reliability in previous research (Vitacco & Kosson, 2010) which was replicated in our raters (ICC = 0.92). It should be noted that the raters were blind to the randomly assigned condition and to psychopathy scores when coding was conducted.
2.3.3. The CIS Participants in both conditions were interviewed about the missing $10. The CIS was broken up into 5 sections for this study; 1) baseline, 2) forward telling of the story, 3) backward telling of the story, 4) a second forward telling, and 5) a “challenge”. We were most interested whether introduction of cognitive load (in stage 3) would result in changes in nonverbal behavior. After the participant responded to baseline questions, the interrogator began the cognitive interview. Participants were asked to recall the events in the previous room: a) chronologically, b) in reverse-order, c) chronologically again, and d) challenged regarding the facts. Participants were all told that the interviewer could not determine whether the person was telling the truth, and all were able to keep the $10.
2.3. Procedures Participants were randomly assigned to the truth or false-alibi condition using a random number generator.
2.3.3.1. Video recordings. Two video cameras were used with one camera placed in each of the two rooms. The video camera in the first room was used to record a) the interaction between the researcher and the participant, and b) to assure that participants in the truthful condition did not take money from the wallet and that participants in the deceptive condition did take the money. In the second room, the video camera was used to record the interview between the interviewer and the participant, and for subsequent coding of the nonverbal behaviors under examination. The camera was aimed at a chair where the participant was to be seated and was realigned for each participant so its visual field was from head to knee. After the CIS interview, participants completed the SRP-4.
2.3.1. Truthful condition On arrival, the participant engaged in a game of Connect Four with one of the research assistants. Connect Four is a two-player game. Players take turns dropping discs from the top into a grid. The object of the game is to form a line of four discs before your opponent (the line can be vertical, horizontal, or diagonal). While playing the game, the researcher engaged participants in conversation about a variety of everyday topics. After approximately five to 7 min, another researcher entered to grab a textbook, and left again. Game-play continued for another 5 min. At that point, the researcher stepped out of the room to answer a phone call, leaving the participant alone. After re-entering the room, game-play resumed. Three minutes later, the second researcher returned to obtain his wallet, and found that $10 was missing from it. The other researcher reported that the participant was only left alone in the room for a brief period of time while she took a phone call. The second researcher left to engage the help of another researcher to help determine what happened. The participant was then interviewed by the third researcher in a separate room. Participants were informed that if they were able to convince the interviewer that they did not take the money, they would earn $10.
3. Results To establish how nonverbal behaviors play out during the Cognitive Interview for Suspects (CIS) for people in the truthful and false alibi conditions, a mixed MANOVA was conducted to look at the nonverbal cues over the stages of the interview (baseline, first forward telling, backward telling, second forward telling, and challenge). Multivariate and univariate results are given in Table 1. A power analysis conducted in G*Power 3.1 (Faul, Erdfelder, Lang, & Buchner, 2007) found that a Table 1 Results of mixed MANOVA.
2.3.2. False-alibi condition The participant was provided with a constructed alibi describing the general outline of the truthful condition. They were instructed to design an alibi around the outline and to add more details. The instructions conclude by telling the participant to take $10 from a wallet that is sitting on the desk across from them. Participants were also informed that they would be interviewed by another researcher regarding the missing money. Participants were given 10 min to practice their alibi, with the goal of convincing the interrogator that they did not take the $10, and that, if successful, they would be able to keep the money. The instructions were as follows:
Multivariate Tests Between Subjects Within Subjects Univariate Tests Group
“You entered the room and played a few games of connect four with [researcher two]. Connect four is a board game similar to tic-tac-toe played with discs similar to checkers pieces. The goal of the game is to be the first to line up 4 pieces on the board while taking alternating turns. A short time later, [researcher one], who shares the laboratory, enters the room and you all have a brief conversation and he leaves. The game continues until [researcher two] receives a phone call and leaves the
Stage
Stage × Group
53
df
F
p
ηp2
Group Stage Group × Stage
4, 145 16, 133 16, 133
39.95 10.23 1.88
< .001 < .001 .028
.524 .552 .184
Blinks Beats Trunk Gaze Blinks Beats Trunk Gaze Blinks Beats Trunk Gaze
1, 1, 1, 1, 4, 4, 4, 4, 4, 4, 4, 4,
1.76 26.4 7.6 115.35 4.85 4.31 1.27 41.87 4.54 3.9 0.87 0.88
.19 < .001 .007 < .001 .001 .002 .009 < .001 .001 .004 .484 .477
.012 .151 .049 .438 .032 .028 .009 .22 .03 .026 .006 .006
148 148 148 148 592 592 592 592 592 592 592 592
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gaze (there was a significant decrease in direct gaze), although blinking and beats comparisons approached significance.
Table 2 Descriptive statistics for SRP-4 and nonverbal behaviors at baseline.
Variable Age Factor 1 Factor 2 Total SRP Blinksa Beatsa Trunka Direct Gazea
Truthful
N = 71
False Alibi
N = 79
Mean 20.58 78.48 67.95 146.44 0.37 0.005 0.01 2.59
SD 2.96 16.64 15.19 29.06 0.02 0.009 0.002 0.07
Mean 21.32 77.06 67.24 144.30 0.42 0.065 0.02 1.57
SD 3.78 15.41 14.66 27.22 0.02 0.008 0.002 0.065
3.1. Psychopathic traits
(F) p 1.75 (.19) 2.75 (.10) 0.40 (.53) 1.56 (.21) 1.76 (.19) 26.40 (< .001) 7.60 (.007) 115.35 (< .001)
Our second objective for the study was to examine whether individual differences, such as psychopathic traits, influence changes in nonverbal cues over the course of the Cognitive Interview for Suspects. We conducted bivariate correlational analyses between psychopathic traits (Factor 1, Factor 2, and total SRP) and changes in beats, blinks, trunk movements, and direct eye gaze from the backward telling (when cognitive load was introduced) to the baseline level. We conducted these correlations separately for truthful and false-alibi conditions (see Table 4). Psychopathy was unrelated to changes in nonverbal cues in the truthful condition. However, in the false-alibi condition, Factor 1, Factor 2, and total SRP scores were significantly positively correlated with change scores for trunk movements (r (78) = 0.25, p < .05; r (78) = 0.32, p < .05; r (78) = 0.32, p < .05, respectively; all medium effect sizes), indicating that people higher on psychopathic traits had a larger increase in trunk movements at the introduction of cognitive load. Fig. 5 illustrates this relationship over the entire cognitive interview. It should be noted that trunk movements were not an important indicator in the general sample, highlighting the importance of examining individual differences.
a Per minute, estimated marginal means from MIXED ANOVA (irrespective of interview stage); significant differences between groups in bold.
total of 78 and 134 participants were needed for such an analysis, assuming a small/medium to medium effect size, indicating that we had an adequate sample size to test our predictions. All multivariate tests were significant, as expected (group, stage, and the interaction between stage and group. Group and stage were large effects, while the interaction was small to moderate. Univariate repeated measures tests found that blinking, beats, and direct eye gaze changed significantly over the course of the CIS (increased blinking, decreased hand gestures and direct eye gaze with increase in cognitive load), and that beats, trunk movements, and direct eye gaze differed between groups (see also Table 2). Figs. 1 through 4 illustrate the nonverbal behaviors at each stage of the CIS (by group). The interaction between group and CIS stage was a significant predictor for frequency of blinking and beats. To determine whether the increase in cognitive load was accompanied by a significant change in blinking, beats, and eye gaze, we used contrasts to test the backwards telling against baseline and the first forward telling (both prior to the increase in cognitive load). As can be seen in Table 3, the backwards telling was significantly different from baseline levels for all three nonverbal cues. The only cue that was significantly different at the backwards telling versus the first forward telling was direct eye
4. Discussion In general, we predicted that nonverbal cues would change with increased cognitive load, and our main objective was to examine whether those changes were in line with the heightened anxiety or cognitive load arguments. If the cognitive load argument holds, direct eye gaze should increase (Mann et al., 2012) and blinking and gesturing should decrease (Vrij et al., 2008), though Vrij et al. state that some research suggests increasing blinking and hand gestures with the implementation of cognitive load, suggesting that cognitive load may also
Fig. 1. Change in blinks per minute throughout the Cognitive Interview for Suspects (CIS). 54
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Fig. 2. Beats per minute over the course of the Cognitive Interview for Suspects.
Fig. 3. Change in trunk movements over the course of the Cognitive Interview for Suspects (CIS).
the mechanism for changes in nonverbal behavior is related to an increase in cognitive load. However, as found by Vrij et al., 2008), blinking increased as the interview progressed, which is inconsistent with some research finding that blinking is either unrelated to deception in interview settings (Mann et al., 2002; Vrij & Mann, 2001) or
change nonverbal cues by increasing nervousness on the part of the deceiver. Anxiety is known to increase fidgeting and blinking, while decreasing direct eye gaze. As expected from the cognitive load argument, there was a decrease in beats as the Cognitive Interview for Suspects (CIS) progressed, which provides support for the notion that 55
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Fig. 4. Direct eye gaze over the course of the Cognitive Interview for Suspects (CIS).
negatively related because an increase in cognitive load results in less blinking (Leal, Vrij, Fisher, & van Hooff, 2008). However, these findings are consistent with some of the research in the Vrij et al. (2008) metaanalysis in which blinking increased with the introduction of cognitive load, but that this may be due to heightened anxiety. Trunk movements did not differ as cognitive load was increased. From the perspective of increased cognitive load, we should have seen an increase in direct eye gaze (Mann et al., 2012). However, our findings directly contrasted with this prediction. These findings, in combination with those for blinking, suggest that nervousness/anxiety play a more important role in nonverbal behavior during interrogation contexts than previously thought (e.g. Vrij et al., 2008). Overall, our findings suggest that changes in nonverbal cues over the course of the CIS are in line with both the heightened anxiety and increased cognitive load arguments. Regardless of the reason, nonverbal cues do change over the course of the interview, and also differ between truthful and deceptive conditions. This adds credence to Geiselman's (2012) findings that people's accuracy at judging deception versus truth improved as cognitive load increased. These findings also suggest that using an interview that increases cognitive load is a good way of enhancing the differences between liars and truth tellers, as suggested by Vrij et al. (2008). Findings also suggest that anxiety and cognitive load both affect nonverbal behavior during deception. The increase in blinking and decrease in direct eye gaze both support the anxiety argument, while reduced hand gestures (beats) support the cognitive load argument (e.g. Vrij et al., 2008), as does the fact that the cues were more enhanced when cognitive load was implemented. Given that there was support for both anxiety and cognitive load arguments, it is possible that both mechanisms are at play in determining nonverbal behavior in the interrogation context. Our second aim was to examine how psychopathic traits relate to changes in nonverbal cues as the interview progresses. This is especially important given the tendency of psychopathic individuals to engage in deceptive behavior, especially in an interrogation context (Quayle, 2008). At the bivariate level, psychopathic traits were not significantly
Table 3 Changes in nonverbal cues when cognitive load is added. Cue
Comparison
Blinking
Backwards Backwards Backwards Backwards Backwards Backwards
Beats Direct Eye Gaze
vs. vs. vs. vs. vs. vs.
Baseline Forward 1 Baseline Forward 1 Baseline Forward 1
Mean Diff
SE
p value
0.04 0.017 −0.031 0.01 −0.664 −0.587
0.011 0.011 0.013 0.006 0.059 0.055
.001 .10 .02 .076 < .001 < .001
Table 4 Correlations between psychopathic traits and change in nonverbal behavior with the introduction of cognitive load.
Blinks
Beats
Trunk
Direct Gaze
Condition
N
Factor 1
Factor 2
Total SRP
Truthful False Alibi Baseline Truthful False Alibi Baseline Truthful False Alibi Baseline Truthful False Alibi Baseline
71 79 150 71 79 150 71 79 150 71 79 150
0.04 0.12 −0.10 −0.09 0.04 0.17 0.11 0.25⁎ −0.09 −0.15 0.02 −0.22a
0.12 0.09 0.05 −0.07 0.12 0.17 0.04 0.32⁎⁎ 0.11 −0.14 0.15 −0.09
0.09 0.12 −0.03 −0.09 0.09 0.18 0.08 0.32⁎⁎ 0.01 −0.16 0.11 −0.17
Change was calculated as score in “Backwards” telling minus the baseline score for each behavioral cue. Baseline correlations are the relationships between psychopathic traits and nonverbal cues in general (irrespective of condition, at baseline). a p between .10 and .05. ⁎ = less than 0.05. ⁎⁎ = less that 0.01.
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Fig. 5. Trunk movements per minute by level of psychopathic traits.
comparison to criminals. Thus, if offenders find lying to be more cognitively easy, it is possible they are able to pay better attention to their nonverbal behaviors during deception and maintain better control over them (Porter, Doucette, Woodworth, Earle, & MacNeil, 2008). This differential perception of the ease of being deceptive may be mitigated by the likely increased ability of a university sample to deal with increases in cognitive load. University student samples have higher levels of education, as well as having a fairly rigorous work/school schedule. For these reasons, they may be more practiced at dealing with increases in cognitive load. Future research should focus on garnering an offender samples to determine whether the same relationships hold for forensic samples. Speaking to other methodological issues, the false-alibi group for this study was constructed by having undergraduate students take money from a wallet, and attempting to convince the interviewer of their innocence. This begs the question of whether this type of design is conducive to high stakes lying situations that individuals who have committed a crime are thrust into during police interview. As noted by Ekman (2009), while high stakes lying increases the amount of fear felt by the individual concealing the truth, it also motivates the liar to put forward a strong effort in convincing the interviewer of their innocence. It is quite possible that participants within our sample did not feel that they were in a high stakes situation where failure to convince the interviewer of their innocence would yield detrimental results. Thus, some participants may have taken a ‘go through the motions’ attitude towards the interview knowing that the ‘crime’ they had committed earlier was part of the study, and no detrimental effects would come of it. Thus, it is important for future research to study nonverbal behaviors exhibited during deception in a high stakes situation such as a real-life police interviews. As well, it is possible that changing the methodology pertaining to how the interview room was arranged, and also how some behaviors were coded could yield different results in future studies. For example, deceptive individuals were given 10 min to construct an alibi that they believed would be sufficient in convincing the interviewer of their innocence. As noted by Ekman (1988), one of the main reasons
associated with any of the nonverbal cues at baseline (irrespective of condition). Further, psychopathic traits were unrelated to changes in blinking, beats, and direct eye gaze, suggesting that people with psychopathic traits show similar changes in these cues when cognitive load is increased. This is inconsistent with research conducted by Klaver et al. (2007), who found that Factor 1 scores were related to increased blinking in deceptive situations. Clearly, psychopathic traits do not influence the changes in blinks and beats due to increased cognitive load and/or anxiety during the CIS. However, our finding that changes in trunk movements is specific to people scoring higher on psychopathic traits (and only in the false-alibi condition) reinforces the necessity of considering individual differences in evaluating statement veracity. This finding is consistent with research suggesting that individuals with psychopathic traits use a dominant and distracting interpersonal style to influence others and manage impressions (Kosson et al., 1997), which would clearly be an important consideration when one is in an interrogative context. Indeed, researchers (Klaver et al., 2007; Riggio & Friedman, 1983), have noted the lack of attention paid towards individual characteristics such as personality, and the possibility of these factors playing a role in the nonverbal behavioral cues of deception that are exhibited.
4.1. Limitations and future directions Our study provides some support for the cognitive load and anxiety arguments for nonverbal behavior changes during the cognitive interview, and also points out that consideration of individual differences is important. However, it is important to point out that our results are based on a university sample. This is important because the majority of individuals that are interviewed within a police setting come from an offender population, and research has shown differences between offender and non-offender samples regarding deception. For instance, research by Granhag, Andersson, Stromwall, and Hartwig (2004), showed a significant difference regarding the amount of mental effort used when telling a lie with students reporting more effort needed in 57
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individuals fail to convince other that they are telling the truth is due to not having enough time to adequately prepare themselves. Although in reality, one would not seek to give individuals more time to be better prepared to deceive someone, this raises the question of whether the amount of time given to the participants in this study is similar to the time an offender has to develop an alibi before being interviewed. Obviously, it would be quite difficult to allow a participant the same amount of time as an offender who has been brought in for questioning. Nevertheless, this limitation highlights the importance of future studies gathering data from real life police interviews where offenders have been able to construct an alibi over a longer period of time.
deception in the interrogation room. Law and Human Behavior, 23, 499–516. http:// dx.doi.org/10.1023/A:1022330011811. Klaver, J. R., Lee, Z., & Hart, S. D. (2007). Psychopathy and nonverbal indicators of deception in offenders. Law and Human Behavior, 31, 337–351. http://dx.doi.org/10. 1007/s10979-006-9063-7. Klaver, J. R., Lee, Z., Spidel, A., & Hart, S. D. (2009). Psychopathy and deception detection using indirect measures. Legal and Criminological Psychology, 14, 171–182. http://dx.doi.org/10.1348/135532508X289964. Kohnken, G., Milne, R., Memon, A., & Bull, R. (1999). The cognitive interview: A metaanalysis. Psychology, Crime & Law, 5, 3–27. http://dx.doi.org/10.1080/ 10683169908414991. Kosson, D., Steuerwald, B., Forth, A., & Kirkhart, K. (1997). A new method for assessing the interpersonal behaviour of psychopathic individuals: Preliminary validation studies. Psychological Assessment, 9, 89–101. http://dx.doi.org/10.1037/1040-3590. 9.2.89. Leal, S., Vrij, A., Fisher, R. P., & van Hooff, H. (2008). The time of the crime: Cognitively induced tonic arousal suppression when lying in a free recall context. Acta Psychologica, 129, 1–7. Mann, S., Vrij, A., & Bull, R. (2002). Suspects, lies, and videotape: An analysis of authentic high-stake liars. Law and Human Behavior, 26, 365–376. http://dx.doi.org/10.1023/ A:1015332606792. Mann, S., Vrij, A., Leal, S., Granhag, P., Warmelink, L., & Forrester, D. (2012). Windows to the soul? Deliberate eye contact as a cue to deceit. Journal of Nonverbal Behavior, 36, 205–215. http://dx.doi.org/10.1007/s10919-012-0132-y. Porter, S., Doucette, N. L., Woodworth, M., Earle, J., & MacNeil, B. (2008). Halfe the world knowes not how the other halfe lies: Investigation of verbal and nonverbal signs of deception exhibited by criminal offenders and non-offenders. Legal and Criminological Psychology, 13, 27–38. http://dx.doi.org/10.1348/ 135532507X186653. Quayle, J. (2008). Interviewing a psychopathic suspect. Journal of Investigative Psychology and Offender Profiling, 5, 79–91. http://dx.doi.org/10.1002/jip.83. Raskin, D. C., & Hare, R. D. (1978). Psychopathy and detection of deception in a prison population. Psychophysiology, 15, 126–136. http://dx.doi.org/10.1111/j.1469-8986. 1978.tb01348.x. Riggio, R. E., & Friedman, H. S. (1983). Individual differences and cues to deception. Journal of Personality and Social Psychology, 45, 899–915. http://dx.doi.org/10.1037/ 0022-3514.45.4.899. Rimé, B., Bouvy, H., Leborgne, B., & Rouillon, F. (1978). Psychopathy and nonverbal behaviour in an interpersonal situation. Journal of Abnormal Psychology, 87, 636–643. http://dx.doi.org/10.1037/0021-843X.87.6.636. Seto, M., Khattar, N., Lalumiére, M., & Quinsey, V. (1997). Deception and sexual strategy in psychopathy. Personality and Individual Differences, 22, 301–307. http://dx.doi.org/ 10.1016/S0191-8869(96)00212-7. Spence, S., Farrow, T., Herford, A., Wilkinson, I., Zheng, Y., & Woodruff, P. (2001). Behavioural and functional anatomical correlates of deception in humans. Neuroreport: For Rapid Communication of Neuroscience Research, 12, 2849–2853. http://dx.doi.org/10.1097/00001756-200109170-00019. Vitacco, M. J., & Kosson, D. S. (2010). Understanding psychopathy through an evaluation of interpersonal behavior: Testing the factor structure of the interpersonal measure of psychopathy in a large sample of jail detainees. Psychological Assessment, 22, 638–649. http://dx.doi.org/10.1037/a0019780. Vrij, A. (1995). Behavioral correlates of deception in a simulated police interview. Journal of Psychology: Interdisciplinary and Applied, 129, 15–28. http://dx.doi.org/10.1080/ 00223980.1995.9914944. Vrij, A. (2000). Detecting lies and deceit: The psychology of lying and the implications for professional practice. Chichester, England: Wiley. Vrij, A. (2004). Why professionals fail to catch liars and how they can improve. Legal and Criminological Psychology, 9, 159–183. http://dx.doi.org/10.1348/ 1355325041719356. Vrij, A., & Mann, S. (2001). Telling and detecting lies in a high-stake situation: The case of a convicted murderer. Applied Cognitive Psychology, 15, 187–203. http://dx.doi.org/ 10.1002/1099-0720(200103/04)15:2<187::AID-ACP696>3.0.CO;2-A. Vrij, A., & Mann, S. (2003). Deception detection. In C. Bass, & D. Oakley (Eds.). P. Halligan (pp. 348–362). Malingering and illness deception: Oxford University Press. Vrij, A., Mann, S., Fisher, R., Leal, S., Milne, R., & Bull, R. (2008). Increasing cognitive load to facilitate lie detection: The benefit of recalling an event in reverse order. Law and Human Behavior, 32, 253–265. http://dx.doi.org/10.1007/s10979-007-9103-y. Williams, K. M., Nathanson, C., & Paulhus, D. L. (2003). Structure and validity of the SelfReport Psychopathy Scale-III in normal populations. 111th Annual Convention of the American Psychological Association. Williams, K. M., Paulhus, D. L., & Hare, R. D. (2007). Capturing the four-factor structure of psychopathy in college students via self-report. Journal of Personality Assessment, 88, 205–219. http://dx.doi.org/10.1080/00223890701268074.
4.2. Implications Our study found support for the idea that nonverbal cues change when cognitive load is increased, and that the changes are consistent with an increase in anxiety and cognitive load. This suggests that both mechanisms are important in determining nonverbal behavior in the interrogation context. Regardless of the reason behind the changes, it does appear that changes in nonverbal behavior could be used in assessing statement veracity, should the findings replicate with higher stakes deception and in other samples. References Akehurst, L., Kohnken, G., Vrij, A., & Bull, R. (1996). Lay persons' and police officers' beliefs regarding deceptive behaviour. Applied Cognitive Psychology, 10, 461–471 (doi: 10.1002/(SICI)1099-0720(199612)10:6 < 461::AID-ACP413 > 3.0.CO;2-2). Billings, F. (2004). Psychopathy and the ability to deceive. Dissertation65. Abstracts International. Book, A. S., Starzyk, K., Holden, R., Wasylkiw, L., & Edwards, M. (2006). Psychopathy and experimentally induced deception in self-report assessment. Personality and Individual Differences, 41, 601–608. http://dx.doi.org/10.1016/j.paid.2006.02.011. Bull, R. (1989). Can training enhance the detection of deception? In J. C. Yuille (Ed.). Credibility assessment (pp. 83–97). Dordrecht, Netherlands: Kluwer. Buller, D., & Burgoon, J. (1996). Interpersonal deception theory. Communication Theory, 6, 203–242. DePaulo, B. (1994). Spotting lies: Can humans learn to do better? Current Directions in Psychological Science, 3, 83–86. http://dx.doi.org/10.1111/1467-8721.ep10770433. DePaulo, B., & Kirkendol, S. (1989). The motivational impairment effect in the communication of deception. In J. C. Yuille (Ed.). Credibility assessment (pp. 51–70). Dordrecht, the Netherlands: Kluwer. DePaulo, B. M., Lindsay, J. J., Malone, B. E., Muhlenbruck, L., Charlton, K., & Cooper, H. (2003). Cues to deception. Psychological Bulletin, 129, 74–118. http://dx.doi.org/10. 1037/0033-2909.129.1.74. Ekman, P. (1988). Lying and nonverbal behaviour: Theoretical issues and new findings. Journal of Nonverbal Behavior, 12, 163–175. http://dx.doi.org/10.1007/BF00987486. Ekman, P. (2009). Lie catching and micro expressions. In C. Martin (Ed.). The philosophy of deception (pp. 118–133). Oxford University Press. Faul, F., Erdfelder, E., Lang, A.-G., & Buchner, A. (2007). G*Power 3: A flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behavior Research Methods, 39, 175–191. Geiselman, E. R. (2012). The cognitive interview for suspects (CIS). American Journal of Forensic Psychology, 30, 5–20. Gilbert, D. (1991). How mental systems believe. American Psychologist, 46, 107–119. Gillstrom, B. J., & Hare, R. D. (1988). Language-related hand gestures in psychopaths. Journal of Personality Disorders, 2, 21–27. http://dx.doi.org/10.1521/pedi.1988.2. 1.21. Granhag, P., Andersson, L. O., Stromwall, L. A., & Hartwig, M. (2004). Imprisoned knowledge: Criminals' beliefs about deception. Legal and Criminological Psychology, 9, 103–119. http://dx.doi.org/10.1348/135532504322776889. Granhag, P., & Stromwall, L. A. (2002). Repeated interrogations: Verbal and nonverbal cues to deception. Applied Cognitive Psychology, 16, 243–257. http://dx.doi.org/10. 1002/acp.784. Hare, R. D. (2003). The Hare Psychopathy Checklist – Revised (PCL-R) (2nd ed.). Toronto, Ontario: Multi-Health Systems. Kassin, S., & Fong, C. (1999). I'm innocent! Effects of training on judgments of truth and
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The effect of cognitive load on nonverbal behavior in the cognitive interview for suspects
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P. Frosina, M. Logue, A. Book , T. Huizinga, S. Amos, S. Stark Brock University, St. Catharines, ON, Canada
A R T I C LE I N FO
A B S T R A C T
Keywords: Interrogation Nonverbal cues Cognitive interview Cognitive load Psychopathy
We investigated whether cognitive load results in changes to nonverbal behavior in the context of interrogation, and whether psychopathic traits affected this relationship. Cognitive load was implemented by using the cognitive interview for suspects (CIS). Onehundred- and-fifty undergraduate students were assigned to one of two conditions: 1) a true event, where they played a game with a confederate, and money went missing from a wallet in the room, or 2) a false-alibi condition, where they read a scenario similar to the true event (in order to create a feasible alibi), and were instructed to steal $10 from the wallet. Blinking, hand gestures, trunk movements, and direct eye gaze were coded at each point in the CIS. Regardless of condition, the increase in cognitive load had the effect of increasing blinking and decreasing hand gestures and direct eye gaze. There were significant interactions between CIS stage and experimental condition for blinks and hand gestures, where people in the false alibi condition had a sharper increase in blinking, and decrease in hand gestures when cognitive load was introduced. Psychopathic traits did not affect the utility of above cues, but change in trunk movements was positively correlated with psychopathy in the false alibi condition.
1. Introduction Police are trained to use nonverbal cues to detect deception (Bull, 1989), but their accuracy hovers around chance, regardless of experience (Vrij, 2000, 2004). In fact, training in traditional interrogation techniques, (i.e. Reid technique) actually result in decreased accuracy (Kassin & Fong, 1999). Cues used include gaze-aversion, an increase in hand/ft movements, and an increase in fidgeting, which are thought to increase due to heightened anxiety or nervousness when being deceptive. The most commonly stereotyped cue is gaze-aversion (e.g. Akehurst, Kohnken, Vrij, & Bull, 1996) which actually has little association with deception, according to a comprehensive meta-analysis (DePaulo et al., 2003). In fact, a recent study suggests that deception is characterized by increased deliberate eye-contact (Mann et al., 2012). DePaulo et al.'s meta-analysis did not find any cues that reliably discriminate between lies/truths. It should be noted that most studies that have been conducted have used student samples in a laboratory context, and only three used forensic samples. In one study of actual interrogations, Mann, Vrij, and Bull (2002) found that liars blinked less, but no relationship was observed for gaze-aversion, illustrators, or hand/arm movements. Approximately half of the sample showed gazeaversion during deception, while the other half showed less gazeaversion, suggesting that there may be individual differences in how
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deception is expressed in nonverbal behavior. Another possible reason for mixed findings is that deception causes changes in nonverbal behavior that may differ between individuals. Thus, it would be important to examine these cues in relation to baseline behaviors. Previous research does suggest that prior familiarity with an individual increases accuracy of deception detection (e.g. DePaulo, 1994). We can exaggerate differences between liars and truth tellers by increasing cognitive load (i.e. making deception more cognitively demanding; Vrij et al., 2008). Deception is already more cognitively demanding than truth telling for a number of reasons, as discussed by Vrij et al. For example, the deceiver has to formulate a story and remind themselves of the details of the story (DePaulo et al., 2003) and deception requires a good deal of self-monitoring in order to appear to be honest (DePaulo & Kirkendol, 1989). Further, the deceiver must invest energy into monitoring the interviewer to determine whether the lie is being believed (Buller & Burgoon, 1996). The deceiver also has to attempt to suppress the truth (Spence et al., 2001). Overall, then, deception requires deliberate mental effort that is unnecessary when telling the truth (Gilbert, 1991). Because deception is cognitively demanding, some researchers have suggested that the nonverbal cues that should be associated with deception are those that are associated with increased cognitive load. Unlike the nonverbal cues associated with anxiety (e.g. increased
Corresponding author. E-mail addresses: [email protected] (P. Frosina), [email protected] (A. Book).
https://doi.org/10.1016/j.paid.2018.03.012 Received 15 August 2017; Received in revised form 23 February 2018; Accepted 7 March 2018 0191-8869/ © 2018 Elsevier Ltd. All rights reserved.
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blinking and gesturing; Vrij et al., 2008), cognitive load reduces fidgeting, gesturing, and blinking. This has led a number of researchers to suggest that these could be cues to deception, given its cognitive demands (e.g. Mann et al., 2002; Vrij & Mann, 2003). Vrij et al. (2008) attempted to enhance the differences between liars and truth tellers, having participants tell stories in reverse chronological order in an attempt to increase cognitive load. Participants were randomly assigned to a reverse order or chronological order condition. As expected, more verbal cues to deceit were observed in the reverse order condition, but, also, nonverbal behavior that is typically associated with anxiety increased, including blinking and hand/foot movements. While gaze-aversion was measured, no results were reported. These findings suggest that not only is telling stories in the reverse order more cognitively demanding, it may also increase anxiety, resulting in an increase in the nonverbal behavior associated with anxiety. Vrij et al. (2008) suggest that a cognitively demanding interview will be especially problematic for people attempting to be deceptive, as deception is cognitively demanding on its own. One interview that does increase cognitive load is the cognitive interview for suspects (CIS) developed by Geiselman (2012). The CIS increases cognitive load by asking the suspect to recount their story in different orders (e.g. backwards). The cognitive interview is an empirically validated method for interviewing witnesses and victims (reviewed by Geiselman, 2012), elicits more information (and more correct information), and has excellent reliability and validity (Kohnken, Milne, Memon, & Bull, 1999). As mentioned, this interview has recently been adapted for use with suspects (Geiselman, 2012). Not only does the CIS increase cognitive load, but also cues to deception can be examined at different points in the interview, allowing the interviewer to see changes in behavior as cognitive load increases. As suggested by Vrij et al. (2008), discrepancies in nonverbal behaviors should occur with the addition of cognitive load. Because some previous findings suggest that individual differences exist for some nonverbal cues (e.g. gaze aversion in the Mann et al., 2002), we sought to determine whether psychopathic traits, which include a tendency to make use of deception and manipulation (Hare, 2003) might influence the display of nonverbal cues during deception. As well, psychopaths are responsible for a disproportionate amount of crime (Quayle, 2008) and, thus, are overrepresented in the legal system (Hare, 2003). People with psychopathic traits do tend to utilize deception more often than other people (Seto, Khattar, Lalumiére, & Quinsey, 1997), and there is some evidence that they may be better at it than others (Billings, 2004; Book, Starzyk, Holden, Wasylkiw, & Edwards, 2006), although Klaver, Lee, Spidel, and Hart (2009) found that raters were better able to pick up on deception in psychopaths than in non-psychopaths, and Raskin and Hare (1978) did not find any differences in arousal during deception. Though findings are mixed, it is clear that deception detection is an important part of the interrogation process, and may be impacted by individual differences such as psychopathy (Klaver et al., 2009). Fitting with the idea that psychopaths have a dominant interpersonal style is Quayle's (2008) assertion that psychopathic suspects will try to charm and outwit the interrogator, including using distracting and dominant nonverbal behavior, such as using more hand gestures, moving towards the interviewer, and direct eye contact. While little research has been conducted looking at nonverbal behavior and deception in relation to psychopathy, a number of studies have examined their nonverbal behavior in interpersonal situations and interviews. In the only study to examine the relationship between nonverbal behaviors and deception in individuals with psychopathic traits, Klaver, Lee, and Hart (2007), asked inmates from a federal prison to tell a true story regarding their crime, and a false story about a crime they didn't commit. Regardless of condition, people scoring higher on psychopathy displayed more blinking and illustrators (Klaver et al.). The researchers suggested that the increase in blinking may serve to
help psychopaths manage the impression they give to the interviewer, however further research is needed to validate this claim. These findings contradict previous studies investigating blinking behavior in deceitful suspects (Mann et al., 2002; Vrij & Mann, 2001), and shed light of the possibility of interpersonal traits associated with psychopathy moderating nonverbal behaviors in deceptive psychopaths (Klaver et al.). With regard to the increase in illustrator usages, Klaver et al. touched on previous studies showing interpersonal characteristics of psychopathy being associated with an increase in hand gestures (Gillstrom & Hare, 1988; Rimé, Bouvy, Leborgne, & Rouillon, 1978). Research by Gillstrom and Hare (1988), examined hand gestures from videotaped interviews of individuals scoring high, medium and low on the PCL-R. Their results showed psychopaths to employ more hand gestures when compared to non-psychopaths. Specifically, people with psychopathic traits exhibited more beats (hand gestures that are unrelated to speech) compared to those scoring medium or low. It was also theorized that beats might be used to distract the interviewer and gain control over the interview itself (Gillstrom & Hare, 1988). The above findings highlight the need for research to examine factor scores of psychopathy with regards to differences in nonverbal behaviors during deception. The current study seeks to examine whether changes in nonverbal behaviors over the course of the CIS are consistent with either a) heightened anxiety (resulting in increased gesturing, gaze aversion, and blinking), b) increased cognitive load (resulting in decreases), or c) both. Because other studies have found that individual differences may be important (Mann et al., 2002), we also predicted that psychopathic traits may be related to changes in nonverbal cues when cognitive load is introduced. 2. Methods 2.1. Participants One-hundred-and-fifty undergraduate students participated (76 women; 74 men (Mage = 20.97; SD = 3.42)) and were randomly assigned to the truthful or false-alibi condition. The study was given approval to proceed by the university Research Ethics Board. 2.2. Measures 2.2.1. Psychopathic traits Psychopathic traits were assessed using the Self-Report Psychopathy Scale: Version III (SRP-III), which has demonstrated strong reliability (α = 0.88) in previous studies (Williams, Nathanson, & Paulhus, 2003). The SRP-III accommodates changes by Hare (2003) pertaining to the expansion of the PCL-R from a two to a four-facet structure examining Antisocial Behavior, Impulsive Thrill-Seeking, Interpersonal Manipulation and Cold Affect (Williams et al., 2003). The SRP-III measures components associated with Factor 1 and Factor 2 of the PCL-R and divides the acquired results into four facets: interpersonal manipulation, callous affect, erratic lifestyle and anti-social behaviors (Williams, Paulhus, & Hare, 2007). Each of these facets has shown to have construct validity with regards to self-reports of anti-social behaviors as well as personality characteristics (Williams et al., 2007), and has shown to be a valid and reliable measure of subclinical psychopathic traits (Williams et al., 2003). The measure consists of 64 items rated on a five-point scale with potential responses ranging from 1 (disagree strongly) to 5 (strongly agree). Internal consistencies in the present study support the reliability of the measure (alphas range from 0.75 to 0.83 for Interpersonal Manipulation, Callous Affect, Erratic Lifestyle, and Antisocial Behavior). 2.2.2. Nonverbal behaviors Nonverbal behaviors were coded employing techniques showing acceptable reliability in previous studies (e.g. Granhag & Stromwall, 52
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room before returning. The game continues until [research confederate] comes back into the lab and locates the wallet that is on the desk. This person opens the wallet, and claims that there is $10 missing.” “The wallet is sitting on the table in the corner of the room. Take the $10 out of the wallet. You will be interviewed by a separate person to determine whether you took the $10. If you convince the interviewer that you did not take the money, you will get to keep the $10.”
2002; Vrij, 1995). To establish interrater reliability, two raters coded the nonverbal behaviors for 10 randomly chosen participants. After we established that interrater reliability was acceptable, the raters each coded half of the remaining interviews. Nonverbal behaviors under investigation included blinking (frequency), beats (frequency), and trunk movements (frequency). Blinking, beats, and trunk movements were coded as frequency of the behavior per minute. Intraclass correlations (ICC's) were deemed acceptable (0.96, 0.83, and 0.71 for blinking, beats, and trunk movements, respectively), and the tw raters each coded half of the remaining participant videos. Direct eye gaze was coded according to the instructions for the interpersonal measure of psychopathy (IMP) (Kosson, Steuerwald, Forth, & Kirkhart, 1997). More specifically, a participant could be scored as 0 (indicating that the behavior was not exhibited at all), 1 (the behavior was somewhat evident), 2 (the behavior was very evident), or 3 (the behavior was exhibited consistently/frequently). The IMP has shown to have strong inter-rater reliability in previous research (Vitacco & Kosson, 2010) which was replicated in our raters (ICC = 0.92). It should be noted that the raters were blind to the randomly assigned condition and to psychopathy scores when coding was conducted.
2.3.3. The CIS Participants in both conditions were interviewed about the missing $10. The CIS was broken up into 5 sections for this study; 1) baseline, 2) forward telling of the story, 3) backward telling of the story, 4) a second forward telling, and 5) a “challenge”. We were most interested whether introduction of cognitive load (in stage 3) would result in changes in nonverbal behavior. After the participant responded to baseline questions, the interrogator began the cognitive interview. Participants were asked to recall the events in the previous room: a) chronologically, b) in reverse-order, c) chronologically again, and d) challenged regarding the facts. Participants were all told that the interviewer could not determine whether the person was telling the truth, and all were able to keep the $10.
2.3. Procedures Participants were randomly assigned to the truth or false-alibi condition using a random number generator.
2.3.3.1. Video recordings. Two video cameras were used with one camera placed in each of the two rooms. The video camera in the first room was used to record a) the interaction between the researcher and the participant, and b) to assure that participants in the truthful condition did not take money from the wallet and that participants in the deceptive condition did take the money. In the second room, the video camera was used to record the interview between the interviewer and the participant, and for subsequent coding of the nonverbal behaviors under examination. The camera was aimed at a chair where the participant was to be seated and was realigned for each participant so its visual field was from head to knee. After the CIS interview, participants completed the SRP-4.
2.3.1. Truthful condition On arrival, the participant engaged in a game of Connect Four with one of the research assistants. Connect Four is a two-player game. Players take turns dropping discs from the top into a grid. The object of the game is to form a line of four discs before your opponent (the line can be vertical, horizontal, or diagonal). While playing the game, the researcher engaged participants in conversation about a variety of everyday topics. After approximately five to 7 min, another researcher entered to grab a textbook, and left again. Game-play continued for another 5 min. At that point, the researcher stepped out of the room to answer a phone call, leaving the participant alone. After re-entering the room, game-play resumed. Three minutes later, the second researcher returned to obtain his wallet, and found that $10 was missing from it. The other researcher reported that the participant was only left alone in the room for a brief period of time while she took a phone call. The second researcher left to engage the help of another researcher to help determine what happened. The participant was then interviewed by the third researcher in a separate room. Participants were informed that if they were able to convince the interviewer that they did not take the money, they would earn $10.
3. Results To establish how nonverbal behaviors play out during the Cognitive Interview for Suspects (CIS) for people in the truthful and false alibi conditions, a mixed MANOVA was conducted to look at the nonverbal cues over the stages of the interview (baseline, first forward telling, backward telling, second forward telling, and challenge). Multivariate and univariate results are given in Table 1. A power analysis conducted in G*Power 3.1 (Faul, Erdfelder, Lang, & Buchner, 2007) found that a Table 1 Results of mixed MANOVA.
2.3.2. False-alibi condition The participant was provided with a constructed alibi describing the general outline of the truthful condition. They were instructed to design an alibi around the outline and to add more details. The instructions conclude by telling the participant to take $10 from a wallet that is sitting on the desk across from them. Participants were also informed that they would be interviewed by another researcher regarding the missing money. Participants were given 10 min to practice their alibi, with the goal of convincing the interrogator that they did not take the $10, and that, if successful, they would be able to keep the money. The instructions were as follows:
Multivariate Tests Between Subjects Within Subjects Univariate Tests Group
“You entered the room and played a few games of connect four with [researcher two]. Connect four is a board game similar to tic-tac-toe played with discs similar to checkers pieces. The goal of the game is to be the first to line up 4 pieces on the board while taking alternating turns. A short time later, [researcher one], who shares the laboratory, enters the room and you all have a brief conversation and he leaves. The game continues until [researcher two] receives a phone call and leaves the
Stage
Stage × Group
53
df
F
p
ηp2
Group Stage Group × Stage
4, 145 16, 133 16, 133
39.95 10.23 1.88
< .001 < .001 .028
.524 .552 .184
Blinks Beats Trunk Gaze Blinks Beats Trunk Gaze Blinks Beats Trunk Gaze
1, 1, 1, 1, 4, 4, 4, 4, 4, 4, 4, 4,
1.76 26.4 7.6 115.35 4.85 4.31 1.27 41.87 4.54 3.9 0.87 0.88
.19 < .001 .007 < .001 .001 .002 .009 < .001 .001 .004 .484 .477
.012 .151 .049 .438 .032 .028 .009 .22 .03 .026 .006 .006
148 148 148 148 592 592 592 592 592 592 592 592
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gaze (there was a significant decrease in direct gaze), although blinking and beats comparisons approached significance.
Table 2 Descriptive statistics for SRP-4 and nonverbal behaviors at baseline.
Variable Age Factor 1 Factor 2 Total SRP Blinksa Beatsa Trunka Direct Gazea
Truthful
N = 71
False Alibi
N = 79
Mean 20.58 78.48 67.95 146.44 0.37 0.005 0.01 2.59
SD 2.96 16.64 15.19 29.06 0.02 0.009 0.002 0.07
Mean 21.32 77.06 67.24 144.30 0.42 0.065 0.02 1.57
SD 3.78 15.41 14.66 27.22 0.02 0.008 0.002 0.065
3.1. Psychopathic traits
(F) p 1.75 (.19) 2.75 (.10) 0.40 (.53) 1.56 (.21) 1.76 (.19) 26.40 (< .001) 7.60 (.007) 115.35 (< .001)
Our second objective for the study was to examine whether individual differences, such as psychopathic traits, influence changes in nonverbal cues over the course of the Cognitive Interview for Suspects. We conducted bivariate correlational analyses between psychopathic traits (Factor 1, Factor 2, and total SRP) and changes in beats, blinks, trunk movements, and direct eye gaze from the backward telling (when cognitive load was introduced) to the baseline level. We conducted these correlations separately for truthful and false-alibi conditions (see Table 4). Psychopathy was unrelated to changes in nonverbal cues in the truthful condition. However, in the false-alibi condition, Factor 1, Factor 2, and total SRP scores were significantly positively correlated with change scores for trunk movements (r (78) = 0.25, p < .05; r (78) = 0.32, p < .05; r (78) = 0.32, p < .05, respectively; all medium effect sizes), indicating that people higher on psychopathic traits had a larger increase in trunk movements at the introduction of cognitive load. Fig. 5 illustrates this relationship over the entire cognitive interview. It should be noted that trunk movements were not an important indicator in the general sample, highlighting the importance of examining individual differences.
a Per minute, estimated marginal means from MIXED ANOVA (irrespective of interview stage); significant differences between groups in bold.
total of 78 and 134 participants were needed for such an analysis, assuming a small/medium to medium effect size, indicating that we had an adequate sample size to test our predictions. All multivariate tests were significant, as expected (group, stage, and the interaction between stage and group. Group and stage were large effects, while the interaction was small to moderate. Univariate repeated measures tests found that blinking, beats, and direct eye gaze changed significantly over the course of the CIS (increased blinking, decreased hand gestures and direct eye gaze with increase in cognitive load), and that beats, trunk movements, and direct eye gaze differed between groups (see also Table 2). Figs. 1 through 4 illustrate the nonverbal behaviors at each stage of the CIS (by group). The interaction between group and CIS stage was a significant predictor for frequency of blinking and beats. To determine whether the increase in cognitive load was accompanied by a significant change in blinking, beats, and eye gaze, we used contrasts to test the backwards telling against baseline and the first forward telling (both prior to the increase in cognitive load). As can be seen in Table 3, the backwards telling was significantly different from baseline levels for all three nonverbal cues. The only cue that was significantly different at the backwards telling versus the first forward telling was direct eye
4. Discussion In general, we predicted that nonverbal cues would change with increased cognitive load, and our main objective was to examine whether those changes were in line with the heightened anxiety or cognitive load arguments. If the cognitive load argument holds, direct eye gaze should increase (Mann et al., 2012) and blinking and gesturing should decrease (Vrij et al., 2008), though Vrij et al. state that some research suggests increasing blinking and hand gestures with the implementation of cognitive load, suggesting that cognitive load may also
Fig. 1. Change in blinks per minute throughout the Cognitive Interview for Suspects (CIS). 54
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Fig. 2. Beats per minute over the course of the Cognitive Interview for Suspects.
Fig. 3. Change in trunk movements over the course of the Cognitive Interview for Suspects (CIS).
the mechanism for changes in nonverbal behavior is related to an increase in cognitive load. However, as found by Vrij et al., 2008), blinking increased as the interview progressed, which is inconsistent with some research finding that blinking is either unrelated to deception in interview settings (Mann et al., 2002; Vrij & Mann, 2001) or
change nonverbal cues by increasing nervousness on the part of the deceiver. Anxiety is known to increase fidgeting and blinking, while decreasing direct eye gaze. As expected from the cognitive load argument, there was a decrease in beats as the Cognitive Interview for Suspects (CIS) progressed, which provides support for the notion that 55
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Fig. 4. Direct eye gaze over the course of the Cognitive Interview for Suspects (CIS).
negatively related because an increase in cognitive load results in less blinking (Leal, Vrij, Fisher, & van Hooff, 2008). However, these findings are consistent with some of the research in the Vrij et al. (2008) metaanalysis in which blinking increased with the introduction of cognitive load, but that this may be due to heightened anxiety. Trunk movements did not differ as cognitive load was increased. From the perspective of increased cognitive load, we should have seen an increase in direct eye gaze (Mann et al., 2012). However, our findings directly contrasted with this prediction. These findings, in combination with those for blinking, suggest that nervousness/anxiety play a more important role in nonverbal behavior during interrogation contexts than previously thought (e.g. Vrij et al., 2008). Overall, our findings suggest that changes in nonverbal cues over the course of the CIS are in line with both the heightened anxiety and increased cognitive load arguments. Regardless of the reason, nonverbal cues do change over the course of the interview, and also differ between truthful and deceptive conditions. This adds credence to Geiselman's (2012) findings that people's accuracy at judging deception versus truth improved as cognitive load increased. These findings also suggest that using an interview that increases cognitive load is a good way of enhancing the differences between liars and truth tellers, as suggested by Vrij et al. (2008). Findings also suggest that anxiety and cognitive load both affect nonverbal behavior during deception. The increase in blinking and decrease in direct eye gaze both support the anxiety argument, while reduced hand gestures (beats) support the cognitive load argument (e.g. Vrij et al., 2008), as does the fact that the cues were more enhanced when cognitive load was implemented. Given that there was support for both anxiety and cognitive load arguments, it is possible that both mechanisms are at play in determining nonverbal behavior in the interrogation context. Our second aim was to examine how psychopathic traits relate to changes in nonverbal cues as the interview progresses. This is especially important given the tendency of psychopathic individuals to engage in deceptive behavior, especially in an interrogation context (Quayle, 2008). At the bivariate level, psychopathic traits were not significantly
Table 3 Changes in nonverbal cues when cognitive load is added. Cue
Comparison
Blinking
Backwards Backwards Backwards Backwards Backwards Backwards
Beats Direct Eye Gaze
vs. vs. vs. vs. vs. vs.
Baseline Forward 1 Baseline Forward 1 Baseline Forward 1
Mean Diff
SE
p value
0.04 0.017 −0.031 0.01 −0.664 −0.587
0.011 0.011 0.013 0.006 0.059 0.055
.001 .10 .02 .076 < .001 < .001
Table 4 Correlations between psychopathic traits and change in nonverbal behavior with the introduction of cognitive load.
Blinks
Beats
Trunk
Direct Gaze
Condition
N
Factor 1
Factor 2
Total SRP
Truthful False Alibi Baseline Truthful False Alibi Baseline Truthful False Alibi Baseline Truthful False Alibi Baseline
71 79 150 71 79 150 71 79 150 71 79 150
0.04 0.12 −0.10 −0.09 0.04 0.17 0.11 0.25⁎ −0.09 −0.15 0.02 −0.22a
0.12 0.09 0.05 −0.07 0.12 0.17 0.04 0.32⁎⁎ 0.11 −0.14 0.15 −0.09
0.09 0.12 −0.03 −0.09 0.09 0.18 0.08 0.32⁎⁎ 0.01 −0.16 0.11 −0.17
Change was calculated as score in “Backwards” telling minus the baseline score for each behavioral cue. Baseline correlations are the relationships between psychopathic traits and nonverbal cues in general (irrespective of condition, at baseline). a p between .10 and .05. ⁎ = less than 0.05. ⁎⁎ = less that 0.01.
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Fig. 5. Trunk movements per minute by level of psychopathic traits.
comparison to criminals. Thus, if offenders find lying to be more cognitively easy, it is possible they are able to pay better attention to their nonverbal behaviors during deception and maintain better control over them (Porter, Doucette, Woodworth, Earle, & MacNeil, 2008). This differential perception of the ease of being deceptive may be mitigated by the likely increased ability of a university sample to deal with increases in cognitive load. University student samples have higher levels of education, as well as having a fairly rigorous work/school schedule. For these reasons, they may be more practiced at dealing with increases in cognitive load. Future research should focus on garnering an offender samples to determine whether the same relationships hold for forensic samples. Speaking to other methodological issues, the false-alibi group for this study was constructed by having undergraduate students take money from a wallet, and attempting to convince the interviewer of their innocence. This begs the question of whether this type of design is conducive to high stakes lying situations that individuals who have committed a crime are thrust into during police interview. As noted by Ekman (2009), while high stakes lying increases the amount of fear felt by the individual concealing the truth, it also motivates the liar to put forward a strong effort in convincing the interviewer of their innocence. It is quite possible that participants within our sample did not feel that they were in a high stakes situation where failure to convince the interviewer of their innocence would yield detrimental results. Thus, some participants may have taken a ‘go through the motions’ attitude towards the interview knowing that the ‘crime’ they had committed earlier was part of the study, and no detrimental effects would come of it. Thus, it is important for future research to study nonverbal behaviors exhibited during deception in a high stakes situation such as a real-life police interviews. As well, it is possible that changing the methodology pertaining to how the interview room was arranged, and also how some behaviors were coded could yield different results in future studies. For example, deceptive individuals were given 10 min to construct an alibi that they believed would be sufficient in convincing the interviewer of their innocence. As noted by Ekman (1988), one of the main reasons
associated with any of the nonverbal cues at baseline (irrespective of condition). Further, psychopathic traits were unrelated to changes in blinking, beats, and direct eye gaze, suggesting that people with psychopathic traits show similar changes in these cues when cognitive load is increased. This is inconsistent with research conducted by Klaver et al. (2007), who found that Factor 1 scores were related to increased blinking in deceptive situations. Clearly, psychopathic traits do not influence the changes in blinks and beats due to increased cognitive load and/or anxiety during the CIS. However, our finding that changes in trunk movements is specific to people scoring higher on psychopathic traits (and only in the false-alibi condition) reinforces the necessity of considering individual differences in evaluating statement veracity. This finding is consistent with research suggesting that individuals with psychopathic traits use a dominant and distracting interpersonal style to influence others and manage impressions (Kosson et al., 1997), which would clearly be an important consideration when one is in an interrogative context. Indeed, researchers (Klaver et al., 2007; Riggio & Friedman, 1983), have noted the lack of attention paid towards individual characteristics such as personality, and the possibility of these factors playing a role in the nonverbal behavioral cues of deception that are exhibited.
4.1. Limitations and future directions Our study provides some support for the cognitive load and anxiety arguments for nonverbal behavior changes during the cognitive interview, and also points out that consideration of individual differences is important. However, it is important to point out that our results are based on a university sample. This is important because the majority of individuals that are interviewed within a police setting come from an offender population, and research has shown differences between offender and non-offender samples regarding deception. For instance, research by Granhag, Andersson, Stromwall, and Hartwig (2004), showed a significant difference regarding the amount of mental effort used when telling a lie with students reporting more effort needed in 57
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individuals fail to convince other that they are telling the truth is due to not having enough time to adequately prepare themselves. Although in reality, one would not seek to give individuals more time to be better prepared to deceive someone, this raises the question of whether the amount of time given to the participants in this study is similar to the time an offender has to develop an alibi before being interviewed. Obviously, it would be quite difficult to allow a participant the same amount of time as an offender who has been brought in for questioning. Nevertheless, this limitation highlights the importance of future studies gathering data from real life police interviews where offenders have been able to construct an alibi over a longer period of time.
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