Lie Detection
Also known as:
Truth Verification
Veracity assessment
Psycho physiological stress detection
©Guy Van Damme 2008
History of separating truth
from deception
• In ancient China the suspect held a spoonful of rice in his or her
mouth during a prosecutor's speech. Since salivation was believed
to cease at times of emotional anxiety, the person was considered
guilty if by the end of that speech the rice remained dry.
• For hundreds of years pulse has also been used to detect
deception. A nobleman suspected his wife of infidelity and
informed his advisor of this. A test was arranged at dinner where
the advisor was seated next to the nobleman’s wife. While
conversing with her he casually laid his hand upon her wrist and
mentioned the name of the person suspected by the nobleman.
The lady’s pulse suddenly quickened while it had not when
mentioning her husband’s name. A confession was later obtained.
(Gesta Romanorum 1906)
©Guy Van Damme 2008
• The idea that lying produces physical side-effects (psycho-physiological
analogues) has long been claimed.
• Mosso, with strong encouragement by his mentor Lombroso, used a
“plethysmograph” (developed by Francis Franke) that measures blood
pressure and volume, to determine the influence of emotion and fear on
cardio activity and respiration.
• Lombroso actually applied the experimental use of the plethysmograph
and spygmograph during interrogations.
• Adamkiewicz’s experimental proof that the secretion of sweat is closely
linked to psychological processes, lead Sticker to experiment with the
galvanic skin phenomenon and the development of the first psychogalvanometer.
• With the combination of the three systems: pneumograph; psychogalvanometer and cardiospysmograph, by Arthur MacDonald, the
Polygraph was born.
©Guy Van Damme 2008
Other truth verification
• In 1964, Charles R. McQuiston together with two friends, Wilson Ford and
Alan Bell, developed the first prototype of his “Psychological Stress
Evaluator”. The PSE relied on measuring stress-induced changes to the
“muscle micro-tremor (8-12 Hz)” as displayed in involuntary changes in
the voice. The theory of the micro tremor comes from Lippold who did
indicate that stress causes the muscles to tremble in the 8-12 Hz frequency
• This muscle tremor then reflects on the vocal cords, being muscles
• In less than one century the search for and studies on truth verification
developed four main methods: the polygraph, the voice stress analyzer,
psychological profiling and truth serum.
©Guy Van Damme 2008
The Latest and the Future
• In the middle 90’s, several publications “crucified” the “micro tremor”
technologies. To analyze these, one obviously has to detect and record
them. Normally available hardware just doesn’t “see” 8-12 Hz.
• In 1998, Amir Liberman, Israel, developed and presented for research
“Layered Voice Analysis”, a technology looking at the whole “hearable”
spectrum of the voice. This new technology does not depend on any
micro tremors and can use any microphone and telephone line for data
• Several other technologies are in development, such as “iris control”,
infrared face scanning and the latest: MRI (magnetic resonance
• At present, polygraph, VSA (aka PSE, CVSA) and LVA (and related
technologies) are the most commonly used psycho physiological veracity
assessment tools, world wide.
©Guy Van Damme 2008
• The branch of psychology that is concerned with the physiological
bases of psychological processes
• Study of the interface of mind and body
• Looks at the way psychological activities produce physiological
• Psycho physiological measures are used to study emotion and
attention responses in response to stimuli (for example: a question
©Guy Van Damme 2008
Lying and stress
The act of lying causes stress
Lie-detection consists mainly of stress detection.
Lie-detection systems use physiological data.
The data relies on detecting the stress that a person experiences
when he is lying.
©Guy Van Damme 2008
Nervous System
Central Nervous System
Peripheral Nervous System
Autonomic NS
Somatic NS
STRESS (Fight or Flight)
©Guy Van Damme 2008
• Nobody can live without a certain amount of stress. Crossing a
road, trying to catch a train, or simply a feeling of joy is enough to
'trigger' the stress mechanism. Stress is not necessarily bad; stress is
part of life as every emotion, every activity causes stress (R. D.
Vooijs - 2004)
• Although stress is also associated with positive emotions, lie
detection focuses on negative stress such as stress caused by
anger or fear.
©Guy Van Damme 2008
What is stress?
• everybody has a general notion of what is stress, however, the
wide use of the term 'stress' has led to a multitude of different
• general consensus: the stress concept involves external or internal
stimulation of the organism, which upsets its internal balance
• general agreement that stress involves a series of physiological
and behavioral changes which prepare the organism for the
appropriate coping response, or, the fight or flight mode.
©Guy Van Damme 2008
The effects of stress
• (very complex: only the physiological responses will be discussed)
• Physiological effects:
• induced by the ANS,
• operates involuntary
• can (normally) not be brought under conscious control
©Guy Van Damme 2008
Effects of stress on speech
Sub glottal air
Height of Larynx
Tension and shape of
Regularity of fold
©Guy Van Damme 2008
Lips, tongue, jaw
and pharynx
tension and
Analyzable variables
• As with hand writing analysis, analyzable variables can be found in the voice:
F0 mean: Fundamental frequency
Pitch range: Difference between highest and lowest pitch in an utterance
Pitch variability dispersion of Pitch (e.g. standard deviation)
Pitch perturbation or jitter
Slight variations in the duration of glottal cycles
Pitch contour: Fundamental frequency values plotted over time (intonation)
F1 mean: Frequency of first (lowest) formant
F2 mean: Mean frequency of the second formant
Intensity mean: Energy values for a speech sound wave averaged over an utterance
Intensity range: Difference between highest and lowest intensity value in an utterance
Intensity variability: Measure of dispersion of the intensity values (e.g. standard deviation)
High frequency energy: Relative proportion of energy in the upper region
Speech rate: Length of an utterance
Spectral noise: A-periodic energy components in the spectrum
Zero Crossings: Number of times a sound wave graph crosses the zero line [Scherer '89]
©Guy Van Damme 2008
Summary of the Psychophysiology
Brain  how it manifests Body
(Body Control Centre)
No control over
85-90% of our brain activity
Normal state
Fight or flight
Move (jump) from Para-sympathetic to Sympathetic
•70% of blood directed to major muscles, brain, lungs
•need for more oxygen
•Some glands get an increase in activity, others less:
sweat glands, saliva gland
•Brain gets more oxygen for faster thinking
©Guy Van Damme 2008
Comparing technologies?
Uses system of multiple
sensors, recording:
Heart pulse rate
Blood pressure
Sweat – Galvanic Skin
Response (GSR)
LVA 6.5
VSA (aka PSE, CVSA) is a
“micro tremor” technology,
using the tremor of Lippold (812 Hz frequencies) to
determine the level of honesty
or deception, by measuring
the stress detected in this
spectrum of the voice.
NB: LVA does not use “micro
tremors” in any shape or form.
©Guy Van Damme 2008
Technology based on analysis
of the whole hearable
spectrum of frequencies that
are received from a voice. Up
to 3800 algorithms which
detect states of stress and
emotions, and measure and
grade them accordingly.
LVA 6.50
Investigation Focus Tool
• A professional truth verification system which analyzes a subject’s
voice, using Nemesysco’s Layered Voice Analysis technology
• Allows the investigator to concentrate on the relevant issues while
conducting an investigation by reviewing the subject’s emotional
response to specific questions or topics
• Designed for professional investigators : governments security
organizations, law -enforcement agencies, corporate security
officers, private investigators, etc.
©Guy Van Damme 2008
LVA 6.50
Investigation Focus Tool
• The LVA 6.50 system has two main operation modes:
• Online Mode: real time analysis of face-to-face or over-the-phone
conversations .
• Offline Mode: in-depth analysis of pre-recorded material.
©Guy Van Damme 2008
Core parameters
• Partial list:
General Stress
Emotional Stress
Cognitive Stress
Thinking effort
©Guy Van Damme 2008
LVA 6.50
Investigation Focus Tool
• SPT – A numerical value describing the relatively high frequency range.
The LVA associates this value with the EMO (Emotional Stress Level).
• SPJ – A numerical value describing the relatively low frequency range.
The LVA associates this value with the COG (Cognitive Stress Level).
• JQ - A numerical value describing the distribution uniformity of the
relatively low frequency range. LVA associates this value with the Global
Stress Level.
• AVJ – A numerical value describing the average range of the relatively
low frequencies. LVA associates this with the Thinking Level.
• SOS – Say or Stop. It is a numerical value describing the changes in the
SPT and SPJ within a single sample. The LVA associates this value with fear
and with issues the subject does not want to discuss.
©Guy Van Damme 2008
Real-time analysis of conversations
©Guy Van Damme 2008
Online Mode
• Provides analysis during open conversation and in situations not
limited to the confinements of interrogation room.
• Highlights problematic issues in the conversation with real-time
textual messaging ("Truth", "False Statement", etc.) as well as a
graphs view.
• Allows the investigator to identify the relevant issues in real-time
and focus on those with further questions while discarding the
irrelevant issues, saving precious investigation time, resources and
©Guy Van Damme 2008
Online Mode - Microphone
• Real-time analysis during a face-to-face interview using a
• Ordinary, visible microphone
• High-gain, concealed microphone
• Online mode allows the investigator to record the conversation for
a thorough analysis at later time.
©Guy Van Damme 2008
Online Mode - Telephone
• Allows real-time analysis during a phone conversation
• No special equipment required, just a phone adapter
• Conversation can be recorded for a thorough analysis at later
©Guy Van Damme 2008
Online Mode - process
• Creating the subject’s voice baseline:
• calibrating for 10-14 seconds (as the subject initially speaks).
• Conducting the interview:
• The system analyzes every 1-2 seconds of the subject’s voice
• Visual feedbacks to the investigator:
• indications include simple textual feedbacks such as "Truth", "False
Statement", "Inaccuracy“, “Subject Not Sure”, "High Stress“, etc.
©Guy Van Damme 2008
Online Mode - demo
• [Click on the image for demonstration]
©Guy Van Damme 2008
In-depth analysis of pre-recorded
©Guy Van Damme 2008
Offline Mode
• Thorough analysis of recorded files; either imported or previously
recorded with Online investigation.
• Higher accuracy in analysis
• Uses more parameters for increased accuracy of results.
• Allows manual removal of noise and improvement of the sound quality
• Provides textual and graphic feedbacks
• Manages previous recordings/ investigations in a simple database
©Guy Van Damme 2008
Offline Mode - demo
• [Click on the image for demonstration]
©Guy Van Damme 2008
LVA6.50 - Advantages
©Guy Van Damme 2008
LVA 6.50 - Advantages
• Accurate and difficult to manipulate
• Allows the investigator to focus on relevant directions and reduces
investigation effort and resources.
• Supports Face-To-Face interviews, interviews over the phone or
analysis of recorded material
• Does not require the suspect to be hooked up to a machine.
©Guy Van Damme 2008
LVA 6.50 - Advantages
• The suspect does not have to know that his/her voice is been
analyzed for emotion detection therefore allowing a flexible
• Language independent; detecting emotions in the voice, not the
actual words spoken.
• User friendly interface
©Guy Van Damme 2008
Thank you
©Guy Van Damme 2008