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LIAR?
SUSPECT, LIES AND VIDEO TAPES: AN
ANALYSIS OF AUTHENTIC HIGH-STAKE
              LIARS


 -Samantha Mann, Aldert Vrij and Ray Bull
Background
This study is one of the very few, and the most
extensive to date, which has examined
deceptive behavior in a real-life, high-stakes
setting. The behavior of 16 suspects in their
police interviews has been analyzed. Clips of
video footage have been selected where other
sources (reliable witness statements and
forensic evidence) provide evidence that the
suspect lied or told the truth.
Aim
• To determine if there are systematic
  behavioral indicators to distinguish between
  those who are telling lies and those who are
  telling the truth.
• To determine if cognitive load (complex
  cognitive processes) causes changes in
  behavior relevant to lying or telling the truth
•Real life high
• Deceptive       stake lies
  behaviour      •Cognitive
• Veracity          Load
              •Blind testers
METHOD : laboratory
   experiment
DESIGN: Repeated
    measure
SAMPLE
•4 participants were juveniles :3 aged 13 and other aged 15
• Remainder were adult < 65 years
•15 were Caucasian (where English was their first
language)
•1 participant was of Asian ethnicity (a male whose first
language was Punjabi but who was fluent in English).
• All interviews were conducted in English.

                13                    3
SAMPLE
•Range of crimes:
1. theft (N =9)
2. arson (N =2)
3. attempted rape (N =1)
4. murder (N =4).
•The majority of participants (at least 10 of
16) were well known to the police and had
been interviewed on several occasions
previously, relating to previously committed
offenses.
PROCEDURE
• Police detectives at Kent County Constabulary, UK, were asked if
  they could recollect videotaped interviews in which they were
  involved where the suspect had lied at one point and told the
  truth at another.
• The end result was an hour-long videotape consisting of clips from
  16 suspects. Truths that were selected were chosen so as to be as
  comparable as possible in nature to the lies (a truthful response to
  an easy question such as giving a name and address was not
  comparable to a deceitful response regarding whether or not the
  suspect has committed a murder. Video-footage about names
  and addresses were therefore not included as truths in this study).
• Total of 65 video clips (27 truth / 38 lies)
• Length of clip and length of response varied but not significant in
  terms of analysis of behavior.
• Two observers independently coded behavior and were
  compared for inter-rater reliability on a sample of the videos (not
  all of them)
• Behaviours recorded were: 1) gaze aversion, 2) blinking, 3)
  head movements, 4) self-manipulations, 5) illustrators, 6)
  Hand-finger movements, 7) speech disturbances 8)pauses
• Given the small number of participants and relative large
  number of behaviors, researchers reduced behavioral
  indices by clustering the three types of hand and arm
  movements (illustrators, self manipulations, and
  hand/finger movements) into one category “hand and
  arm movements.” This clustering had no effect on the
  results.
• Each of the coded behaviors was transformed into a
  format in order that truths and lies may be directly
  compared.
For example: Hand & Arm Movements X 60
             Total length of truth/lying
RESULTS
• Data was analyzed using Multivariate
  Analysis of Variance (MANOVA): a statistical
  test procedure for comparing multivariate
  (population) means of several groups.
• Veracity was the only within subject factor
  and the dependent variables were the six
  listed in the table.
TRUTHFUL               DECEPTIVE
    BEHAVIOUR
                      MEAN              SD   MEAN               SD


   GAZE AVERSION      27.82         9.25     27.78          11.76


      BLINKS          23.56         10.28    18.50              8.44


  HEAD MOVEMENTS      26.57         12.34    27.53          20.93


HAND/ARM MOVEMENTS    15.32         14.35    10.80              9.99


      PAUSES          3.73          5.14     5.31               4.95


SPEECH DISTURBANCES   5.22          3.79     5.34               4.93
EVALUATION OF RESULTS
 Individual differences occurred and there was no
    particular behaviour that all liars exhibited.
   50% showed an increase and 50% showed a decrease in
    head movements and speech disturbances while lying.
   56% 44% - gaze aversion
   More participants (69%) showed an than in hand
    movements during deception.
   Blinking and pausing as the majority of participant
    paused longer and blinked less while lying (81%)
DISCUSSION
• The findings of the study give some support for the
  cognitive load process in explaining deceptive
  behaviour.
• Falsifies the stereotypical view of increased
  blinking; Nixon effect
• However, neither cognitive load nor nervousness
  were measured or manipulated before the study
   conclusions were speculative
APPLICATIONS
 Challenges the simplistic views of
  professional lie catchers that a typical of
  deceptive behaviours exists.
 Highlights the importance of establishing a
  baseline behaviour before attempting to
  detect deception.
STRENGTHS

•   Control of variables in lab experiment;
•   inter-rater reliability;
•   specific behaviors identified and measured;
•   quantitative data- reliable
 Different interviewers were used for different participants.
 Sometimes more than one interviewer was present.
 The total number of people present varied.
  Though these factors may have influenced the person’s
  behaviour, the researchers controlled these factors using within
  factor design.
 No comparison between high stake liars and high stake truth
  tellers.
 Small sample size= not generalizable (this was because of the
  limited availability of appropriate tapes and the time
  consuming process of obtaining them) limits generalizability to
  criminals in police custody only.
 People who have been arrested more than once might
  experience less fear and guilt, be more experienced liars.
THE
END

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Suspect, lies and video tapes

  • 2. SUSPECT, LIES AND VIDEO TAPES: AN ANALYSIS OF AUTHENTIC HIGH-STAKE LIARS -Samantha Mann, Aldert Vrij and Ray Bull
  • 3. Background This study is one of the very few, and the most extensive to date, which has examined deceptive behavior in a real-life, high-stakes setting. The behavior of 16 suspects in their police interviews has been analyzed. Clips of video footage have been selected where other sources (reliable witness statements and forensic evidence) provide evidence that the suspect lied or told the truth.
  • 4. Aim • To determine if there are systematic behavioral indicators to distinguish between those who are telling lies and those who are telling the truth. • To determine if cognitive load (complex cognitive processes) causes changes in behavior relevant to lying or telling the truth
  • 5. •Real life high • Deceptive stake lies behaviour •Cognitive • Veracity Load •Blind testers
  • 6. METHOD : laboratory experiment DESIGN: Repeated measure
  • 7. SAMPLE •4 participants were juveniles :3 aged 13 and other aged 15 • Remainder were adult < 65 years •15 were Caucasian (where English was their first language) •1 participant was of Asian ethnicity (a male whose first language was Punjabi but who was fluent in English). • All interviews were conducted in English. 13 3
  • 8. SAMPLE •Range of crimes: 1. theft (N =9) 2. arson (N =2) 3. attempted rape (N =1) 4. murder (N =4). •The majority of participants (at least 10 of 16) were well known to the police and had been interviewed on several occasions previously, relating to previously committed offenses.
  • 9. PROCEDURE • Police detectives at Kent County Constabulary, UK, were asked if they could recollect videotaped interviews in which they were involved where the suspect had lied at one point and told the truth at another. • The end result was an hour-long videotape consisting of clips from 16 suspects. Truths that were selected were chosen so as to be as comparable as possible in nature to the lies (a truthful response to an easy question such as giving a name and address was not comparable to a deceitful response regarding whether or not the suspect has committed a murder. Video-footage about names and addresses were therefore not included as truths in this study). • Total of 65 video clips (27 truth / 38 lies) • Length of clip and length of response varied but not significant in terms of analysis of behavior. • Two observers independently coded behavior and were compared for inter-rater reliability on a sample of the videos (not all of them)
  • 10. • Behaviours recorded were: 1) gaze aversion, 2) blinking, 3) head movements, 4) self-manipulations, 5) illustrators, 6) Hand-finger movements, 7) speech disturbances 8)pauses • Given the small number of participants and relative large number of behaviors, researchers reduced behavioral indices by clustering the three types of hand and arm movements (illustrators, self manipulations, and hand/finger movements) into one category “hand and arm movements.” This clustering had no effect on the results. • Each of the coded behaviors was transformed into a format in order that truths and lies may be directly compared. For example: Hand & Arm Movements X 60 Total length of truth/lying
  • 11. RESULTS • Data was analyzed using Multivariate Analysis of Variance (MANOVA): a statistical test procedure for comparing multivariate (population) means of several groups. • Veracity was the only within subject factor and the dependent variables were the six listed in the table.
  • 12. TRUTHFUL DECEPTIVE BEHAVIOUR MEAN SD MEAN SD GAZE AVERSION 27.82 9.25 27.78 11.76 BLINKS 23.56 10.28 18.50 8.44 HEAD MOVEMENTS 26.57 12.34 27.53 20.93 HAND/ARM MOVEMENTS 15.32 14.35 10.80 9.99 PAUSES 3.73 5.14 5.31 4.95 SPEECH DISTURBANCES 5.22 3.79 5.34 4.93
  • 13. EVALUATION OF RESULTS  Individual differences occurred and there was no particular behaviour that all liars exhibited.  50% showed an increase and 50% showed a decrease in head movements and speech disturbances while lying.  56% 44% - gaze aversion  More participants (69%) showed an than in hand movements during deception.  Blinking and pausing as the majority of participant paused longer and blinked less while lying (81%)
  • 14. DISCUSSION • The findings of the study give some support for the cognitive load process in explaining deceptive behaviour. • Falsifies the stereotypical view of increased blinking; Nixon effect • However, neither cognitive load nor nervousness were measured or manipulated before the study  conclusions were speculative
  • 15. APPLICATIONS  Challenges the simplistic views of professional lie catchers that a typical of deceptive behaviours exists.  Highlights the importance of establishing a baseline behaviour before attempting to detect deception.
  • 16. STRENGTHS • Control of variables in lab experiment; • inter-rater reliability; • specific behaviors identified and measured; • quantitative data- reliable
  • 17.  Different interviewers were used for different participants.  Sometimes more than one interviewer was present.  The total number of people present varied. Though these factors may have influenced the person’s behaviour, the researchers controlled these factors using within factor design.  No comparison between high stake liars and high stake truth tellers.  Small sample size= not generalizable (this was because of the limited availability of appropriate tapes and the time consuming process of obtaining them) limits generalizability to criminals in police custody only.  People who have been arrested more than once might experience less fear and guilt, be more experienced liars.
  • 18.
  • 19.