The study analyzed video recordings of interviews with 16 criminal suspects who initially lied but later told the truth. The researchers coded behaviors like gaze aversion, blinking, and hand movements to identify differences between lying and truth-telling. They found that liars paused longer between responses and blinked less than when telling the truth, which may indicate higher cognitive load while lying. However, there were many individual differences, so no definitive behavioral indicators of lying could be identified.

1. Suspects, Lies, and Videotape : An
Analysis of Authentic High-Stake Liars
2002
Samantha Mann, Aldert Vrij,
and Ray Bull

2. Objectives
 To identify certain body movements, those are
present when a person is lying.
 Differentiate between a novel liar and
authentic liars.
 How did they conduct the study and what did
they find out.

3. Keywords
 High Stakes
 Authentic
 Forensic
 Content Analysis
 Cognitive Load
 Single Blind Study
 Quasi-experiment
 Pearson Correlation Statistical Test (R Value)

4. Introduction
 http://www.youtube.com/watch?v=b1bol0C7_FA
 http://www.youtube.com/watch?feature=player_embedded&v=Ik
XxmMUIx8k
 http://www.youtube.com/watch?feature=player_embedded&v=IFI
ssC2k6SQ
 Are you a liar? You would probably answer "no". Let's ask it
another way. How many times did you say something that
was not completely true last week? For many reasons, the
answer is probably quite a lot! We're all liars some of the
time, but for some people lying may be extremely important.
How do people act when lying is the only think they can do
to keep themselves out of jail? Do they blink a lot? Sweat?
Let's find out.

5.  How to Spot a Liar
 Fidgeting?
 Decreased eye contact?
 Actually most people move less and to date
there has been no credible study done to
show any connection between eye contact
and truthfulness

6.  Background
 The behavior of liars has traditionally been studied
experimentally, in the laboratory
 Can you see a problem with this?
 Vrij and Mann (2001) Differences between lying in ‘real
life settings’ & lying in an ‘experimental situation’ led to
examining videotape of a murder in police custody
 This study extends the findings of that study with a larger
sample

7.  AIM
1. To determine if there are systematic behavioral indicators
to distinguish between those who are telling lies and those
who are telling the truth.
2. To determine if cognitive load causes changes in behavior
related to lying or telling the truth

8.  Cognitive Load- Hypothetical construct used to describe
the load related to the executive control of working
memory.
 • Cognitive psychologists argue that during complex
mental activities the amount of information & interactions
that must be processed simultaneously can either under-
load, or overload the finite amount of working memory
one possesses

9.  Sample
An opportunity sample of 16 police’ suspects
• 13 males & 3 females
• 4 juveniles (three-13 y.o. & one-15y.o.) & 12 adults (under 65).
• 15 were Caucasian (English as a 1st language) & 1 Asian
(Punjabi was his 1st but was fluent English)
All interviews were conducted in English.
Crimes for which participants were being interviewed
• Theft (9)
• Arson (2)
• Attempted rape
• murder (4)
Most participants (10), were known to the police & had been
interviewed about other crimes

10.  Sample
Police detectives at Kent County Constabulary (U.K) were
asked if they could recall videotaped interviews in which they
had participated, where the suspect had initially lied and later
told the truth
Once cases meeting this criterion were found the case files
were gathered up.

11.  Sample
An hour-long videotape consisting of clips from 16 suspects.
The truths that were selected were chosen so they could be
as comparable as possible in nature to the lies
Truthful response to an easy question such as giving a name
and address is not comparable to a deceitful response
regarding whether or not the suspect has committed a
murder.

12.  Method – Natural experiment/quasi
experiment
• The independent variable was not directly
manipulated by the experimenter
1) What was the independent variable?
Whether they decided to tell the truth or lies.
2) What was the dependent variable?
The accompanying body language.

13. Design: Repeated measures
design
The participants had a video
recording of their body
language both when they lied
and later told the truth.

14.  Procedure
1. Total of 65 video clips (27 truth / 38 lies)
2. Length of clip & length of response varied but not
significant in terms of analysis of behavior.

15.  Observers were instructed to ‘code the video
footage’ –
 Content analysis • Not informed about the
hypothesis or nature of the video clips
 What do we call this? deception
 What is it used to control? Demand
characteristics.

16.  Content Analysis
A methodology used in the social sciences for objectively
studying the content of a communication (written work,
speech, film)
It is a quantitative method producing data that is often
percentages or numerical, serving two important purposes:
• to remove much of the subjectivity from summaries
• to simplify the detection of trends

17.  Behaviors recorded
1. Gaze Aversion
2. Blinking
3. Head Movements
4. Speech Disturbances
5. Pauses
6. Hand & Arm Movements (These Were Originally Coded
Individually)
7. Self-manipulations
8. Illustrators
9. Hand-finger Movements

18.  Each of the coded behaviors was transformed into a
format, so that the truths and lies could be directly
compared
 The result was one truth-telling score, and one lie telling
score for each behavior for each participant

19. Controls
1. Two observers told to independently code behavior
were compared for on a sample of the videos (not all of them)
2. What is this called? Observer triangulation to check inter
rater reliabilty
3. What is it used to control? Participant bias
4.A Pearson correlation statistical test • A measure of the
strength of a linear association between two variables
5. Strong consistency between the two coders, in other words
there was no significant difference between the two coders.

20.  Results
1. Behavioral results for the 6 categories were not
significantly different
2. Noticeable differences were found between the hand
and arm movements (truthful 15.31; lying 10.80) and
pauses (truthful 3.73, lying 5.31)
3. The deceptive group paused longer and blinked less
but there were many individual differences
4. http://www.youtube.com/watch?feature=player_em
bedded&v=P_6vDLq64gE

21.  Explanations
Give some support for the cognitive load process in
explaining deceptive behavior, as both fewer blinking and
longer pauses are possible indicators of cognitive load
However, because they did not measure nor manipulate
cognitive load and nervousness in this study, all conclusions
are speculative

22.  Summary
The body language of authentic liars is different from people
who lie in normal situations.
The best indicators are pauses and blinking.

23. Alternative study
 Mann et al conducted a quasi experiment. An alternative
study method might have been to conduct a true lab
experiment.
1. Describe a laboratory experiment as an experimental
method. (5)
2. How could they have conducted an experiment with a
similar aim, but as a true lab experiment?
Write a description of the study, including the who, what,
where and how.(10)
2. What would the advantages and disadvantages of such an
experiment be, compared to the original?
Evaluate this new study
in practical and methodological terms. (10)

24.  Guide
 http://psychtutor.weebly.com/mann-vrij-and-bull---high-
stakes-liars.html
 https://www.google.co.in/search?q=Suspects%2C+Lies
%2C+and+Videotape%3A+An+Analysis+of+Authentic+H
igh-Stake+Liars+-
 http://www.slideshare.net/MrOakes/mann-core-
study?qid=c04a12ab-7071-456e-a16c-
85b872ca11ea&v=&b=&from_search=1