FORENSIC CRIMINOLOGY
AND PSYCHOPHYSIOLOGY;
Truth Verification
tools, with a special study of Truster Pro.
Drs. Guy van Damme
In 1997, I was
asked by Prof. A. Padayachee, to develop a module of Forensic Criminology for
the University of Durban Westville, one particular chapter being "Investigative
tools", meaning all Truth Verification techniques. As a long practising
polygraph operator, qualified in forensic psychophysiology in 1982, I was asked
by Trustech Israel, to analyse their latest product, the Truster Pro.
It soon became
clear that this knowledge should not be restricted to the academic world but be
made available to the real practitioners in the field. To share my knowledge of
Truth Verification tools and the Truster Pro in particular we composed this
article. I hope you enjoy it.
This paper is
directed at people involved, or merely interested, in the fight of crime.
The purpose
is to provide or to improve the basic knowledge of "Truth Verification" needed
by any investigator.
Certain
techniques and different methods of Investigative tools will be discussed
enlarging on the newest tool, the Truster Pro without the intent of neglecting
or degrading the other excellent tools, such as the well known and proven
polygraph.
2.
Investigative Tools, Truth Verification Techniques.
2.1
Introduction.
Mankind, throughout history, has sought and found ways
and means of separating truth from deception.
The science of truth verification however, based
mainly upon psycho-physiological analogues, is barely one hundred years old.
Many stories of inventive procedures have been carried
over from the past.
One ancient legend mentions a method employing the
tail of a donkey.
The donkey was placed in a darkened tent and its tail
was then generously coated with lampblack.
All possible suspects were then asked, one after the
other, to enter the tent and pull the donkey's tail.
They were told that the donkey would only bray if a liar
pulled his tail.
The honourable men obviously having nothing to fear
did indeed pull the donkey's tail and came out of the tent with their hand
blackened with lampblack.
The liar however, afraid of the fact that the donkey
would indeed bray, did not pull the tail and reappeared from the tent with
clean hands.
An interesting technique stemming from ancient China
is the following:
When subjects were interrogated, they were given a
small amount of dry rice, with the instruction to keep the rice under the
tongue.
After the interrogation, he had to spit out the rice
in his hand.
The fortunate people whose rice was wet by saliva
could keep their head. The person whose rice was still dry lost it.
The theory comes down to a well-known phenomenon: the
mouth goes dry when under stressful conditions.
The middle ages in western Europe, followed by the
dark times of the Inquisition, used methods not to be proud of: hot irons, iron
maiden, the wheel, burning at the stake, dunking etc. Ironically, they have proven
to be the least effective.
From these ancient records until today, many
techniques and methods have been invented and tried to ascertain truth and lie,
deception or non-deception, right or wrong.
Sometimes based upon pure psychological methods, sometimes
purely mechanical, sometimes a combination of both, they all come down to the
basic need of knowing the real facts.
The great breakthrough came at the end of the 19th
century (1893) when the well known "father of criminology" Cesare
Lombroso started experimenting with pulse and blood pressure changes in order
to establish verification of truth in answers given to questions by actual
criminal suspects.
The idea of using the pulse as a truth verification
technique was older than that, but Lombroso and his student Angelo Mosso were
the first to actually use a physical device to demonstrate the changes in pulse
and blood volume and to scientifically document the findings.
Already in the middle ages it was related that the
pulse was used as an investigative tool.
A nobleman suspected his wife of infidelity and
informed his advisor of this.
The advisor arranged a test during a dinner party at
which he was seated next to the nobleman's wife.
While conversing he casually laid his hand on the
wrist of the lady 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).
In 1730, just before he died, Daniel Defoe wrote an
essay called "An effectual Scheme for the Immediate Preventing of Street
Robberies and Suppressing all Other Disorders of the Night".
Defoe claimed that taking the pulse rate of a suspect
is a practical, effective and more human method of determination of deception.
"Guilt always carries fear around with it, there
is a tremor in the blood of a thief, that, if attended to, would effectually
discover him, and if charged as a suspicious fellow, on that suspicion only I
would always feel his pulse, and I would recommend it to practice. The innocent
man which knows himself clear and has no surprise upon him; when they cry
"stop thief" he doesn't start; or strive to get out of the way; much
less does he tremble and shake, change countenance or look pale, and less still
does he run for it and endeavour to escape."
Defoe went on:
"It is true some are so hardened in crime that they
will boldly hold their faces, carry it off with an air of contempt, and outface
even a pursuer; but take hold of his wrist and feel his pulse, then you shall
find his guilt; confess he is the man, in spite of bold countenance or a false
tongue...a conscious heart will discover itself by faltering pulse..."
It may be true, that this discovery by the pulsation
of the blood cannot be brought to a certainty, and therefore it is not to be
brought into evidence; but I insist if it be duly and skilfully observed, it
may be brought to be allowed for a just addition to other circumstances,
especially if concurring with other grounds of suspicion (Scott-Kilvert
1965; Ansley 1989).
Mosso, with strong encouragement by his mentor
Lombroso, used for his research on emotion and fear during questioning and
their influence on cardio activity and respiration, a
"plethysmograph".
This instrument, developed by Francis Franke measures
blood pressure and volume.
The use of it revealed periodic undulations in blood
pressure caused by the respiration cycle.
Mosso was the first scientist to report that the
breathing pattern changes under certain stimuli.
He also reported that variations in blood pressure and
the circulation of blood during fear are greater than those resulting from mere
noise and sound.
Mosso's mentor, Cesare Lombroso actually applied
Mosso's experimental blood pressure and pulse tests to actual criminal suspects
on several occasions.
In his second edition of L'Homme Criminel (published 1895) Lombroso describes his experimental use of the plethysmograph and spygmograph during interrogations.
Scientific research towards truth verification thus
started as an academic discipline.
The military forces (with greater budgets than police
forces) quickly became aware of the importance of reliable truth verification
techniques (or better, procuring information from unwilling subjects)
and engaged in their own research.
Dr. Charles E. Cady, a U.S. military surgeon, observed
Rebel officers divulge important information whilst under the influence of
chloroform.
Although not involving himself in the practical
application, he strongly recommended that skilled anaesthetists should
administer pure chloroform to subjects in a well-ventilated room and, whilst
the subject is semiconscious, interrogate him bluntly and pointedly
(Eisenschiml, 1940).
Further developments in scientific truth verification
at the end of the previous century came from F. Galton, who developed the word
association test and Wilhelm Wundt, the founder of the first psychological
laboratory in Leipzig, Germany.
Wundt modified Galton's association method to a
standardised form, still in use.
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.
The three essential components of the modern polygraph
had now been developed, together with the knowledge of word association and
hypnotics (truth serum).
Arthur MacDonald can be described as the first person
to propose the development and the creation of an apparatus combining the three
systems: pneumograph, psychogalvanometer and cardiospysmograph.
The polygraph was born.
Hundreds of scientists from then on worked on the
development of polygraph, word association and so called truth serums.
In 1964, Charles R. McQuiston made a new step in the
truth verification research.
The U.S. Army desired a alternative instrument to the
polygraph with no need for direct connection to the subjects body, one of the
main disadvantages of the polygraph.
He coined the name "voice stress analysis"
and together with two retired friends, Wilson Ford and Alan Bell, he developed
the first prototype of his "Psychological Stress Evaluator".
The PSE relied on measuring stress-induced changes to
the "muscle micro-tremor" as displayed in involuntary changes in the
voice.
In less than one century the science of truth
verification developed four main techniques and instruments, the polygraph, the
voice stress analysis, psychological profiling and truth serum.
2.2
Polygraph
2.2.1
Scope
The scope of this document is to give you the
essential facts about polygraph testing, in order to give you the basic
understanding of what happens if you consult a polygraph examiner, what he can
and cannot do and to make a right choice to consult him or one of his
colleagues using a different truth verification technique.
2.2.2
Underlying principles.
The term " POLY-GRAPH" means literally
" Multiple Writing" (from the Greek Language).
The name is now often connected to the term " Lie
Detector" or as " an instrument for recording of several different
pulsations (as of physiological variables) simultaneously" (Encyclopaedia
Britannica).
The name was derived from the fact that the polygraph,
as opposed to, for example, the GSR or VSA which only record one reading, looks
at various selected physiological activities.
Human beings (as well as any other mammals and most
other living beings) are endowed with a very sophisticated survival mechanism.
Their whole well being depends on the maintenance of
an inner balance, fluids and chemicals, throughout every organ in the body.
This balance is called homeostasis.
In the centre of the brain is a gland called the
Hypothalamus: our internal regulator.
All our unconscious activities such as sleep,
breathing, digestion, pulse, blood volume, respiration etc. are regulated by
the autonomic nervous system, controlled by the hypothalamus.
When our well being is threatened, physically or
psychologically, one of our sensors, hearing, seeing, feeling or even instinct,
will send alarm signals to the autonomic nervous system which will activate its
sympathetic department and take action.
When the ear of the subject receives a potentially
threatening message from the examiner, this stimulus is transferred via sensory
neurones to the temporal lobe of the cerebrum.
Regarding treating the nature of the stimulus the
signal is send to the frontal lobe (the centre for judgement and reasoning)
where the question is perceived and a judgement made.
If the question is perceived as threatening, the alarm
is sent from the frontal lobe through the hypothalamus to the sympathetic
system which will then take appropriate action nl. a sympathetic response.
(Note that this whole process cannot even be
calculated in microseconds, it is semi instantaneous).
The body is now programmed for " fight or
flight" mode.
The adrenal medulla glands will extract adrenaline
(hormones known as epinephrine and norepinephrine) so that certain bodily
functions will alter in order to stand the best chance to survive the emergency.
For example, the blood will be instantly distributed
to the most important areas like the brain and the larger muscles, and in other
parts the arterioles will constrict, preventing blood going to where it is not
needed.
Other very obvious effects will take place, known by
all of us:
* The mouth
gets dry, due to the salivary glands producing much thicker saliva.
* The heart
pumps harder and faster, thereby increasing blood volume and pulse.
*
Stimulation of the respiratory muscles leads to breathing changes.
* The sweat
glands are stimulated and forced to release perspiration.
* The iris
of the eye dilates permitting more light into the eye.
* The anal
and urinary sphincters contract and the bladder relaxes.
*
Involuntary muscles contract.
While the sympathetic system organises this whole
defence system in next to no time, the parasympathetic system, functionally
antagonistic towards his partner, follows up in order to re-establish the
chemical balance of the body.
Without these two antagonistic partners, the defence
system of the body would go into a high build up and cause damage to the body
(E.g.. burst artery in brain). The two of them are essential to maintain a
perfect homeostasis.
All of the above mentioned physiological activity can
be measured.
As Dr. James A. Matte puts it:
"The
forensic psychophysiologist (the polygraph examiner) measures
and
records breathing patterns, heart beat, pulse rate and strength,
changes in
mean blood pressure, and electrodermal responses in
order to
obtain physiological evidence of hypothalamic
activity
including
the sympathetic and the parasympathetic subdivisions of
the
autonomic nervous system during the psychophysiological
veracity
examination ( polygraph examination) on the test."
(J. A.
Matte 1996, Forensic Psychophysiology using the Polygraph)
The " Introduction" briefly outlined the various stages of history of the
polygraph and explained that three basic scientific techniques had to be
developed before the first real polygraph was created.
The polygraph collects physiological data from at
least three systems of the human body:
* The
respiratory system: the examiner will record " thoracic breathing"
and " abdominal breathing".
Convoluted
rubber tubes are placed over the chest and the abdomen.
* Galvanic skin response
(electrodermal).
Two small
metal plates are connected to the fingers (normally the middle section of the
index and ring finger of the left hand). These
plates record the filling up of sweat glands (empty during homeostatic
condition) and the nearly immediate
reabsorbation of the moisture.
* The
Cardiac system: the examiner will record Blood volume and Pulse rate.
A medical
blood pressure cuff containing a rubber bladder is wrapped around the upper right arm, against the
brachial artery. The cuff is connected via the instrument (cardiosphygmograph)
to a hand pump with a pressure indicating gauge.
* Certain
systems (e.g. Lafayette) offer an option where the examiner can measure minor
movements induced by the contraction of involuntary muscles.
These five (thoracic and abdominal breathing, blood
volume, pulse rate and galvanic skin response) or six (movement) readings
will be recorded on "Chart" (see later). Normally the
examiner will do three to four charts.
From these charts, the examiner will do his
calculations (manually or with computerised systems via his software), make his
decision and file a report, which goes to the client.
2.2.3
The Polygraph examination.
2.2.3.1
General.
The typical polygraph examination consist of three
distinctive parts:
* the pre
test interview
* the
actual examination or chart collection phase
* the test
date analysis phase
2.2.3.2
The pre test interview
Most people do not really realise that in fact, the
most important and often the longest phase in a polygraph examination is the
pre test interview.
While the average test will take approximately 90
minutes, the pre test
interview can easily absorb 45 minutes in general.
During the pre test interview the examiner will:
* Talk
nicely with the subject and do his best to put him / her at ease.
* Will give
the subject a detailed explanation of what is going to happen during the actual
testing
phase and confirm his understanding.
* Will
define the subject's legal rights.
* Explain
to the subject what the polygraph is all about and how it
works
(briefly)
* Write
down all the subject's details in order to make the identification sheet attached to the
report.
*Ask certain questions
about the subject's health, if he has eaten over the last 5 - 6 hours, if he
had a good nights rest and is not to tired.
* Talk
about the "incident" or "issue".
* Discuss all the questions which will be asked and make sure the
subject answers them all
confidently and understandingly.
* Ask the
subject one last time if he is prepared to undergo the test and then invite him to take
a seat
in the interviewing chair.
The examiner will then connect the different
components to the subject whilst asking him to sit absolutely still during the
whole time of each chart recording (approximately 4 to 5 minutes).
2.2.3.3
The actual polygraph examination.
Before the pre test interview, the examiner had a
briefing with the client, which will typically be the investigator but, in
certain cases, can be the subject himself.
During this briefing, the examiner has to make up his
mind as to which type of questionnaire he will be using (see later). Depending
on the type of test he will draw up a specific questionnaire, discuss the
relevant questions (see later) with the client and, on his approval, go to the
interview room (see later) to start his pre test interview.
2.2.3.3.1
The interview room.
The ideal interview room is not too small, not too big
(3,5m X 3m). It should be guaranteed have privacy with no possibility of
interference (no telephone).
The furniture has to be sober but adequate: desk and
chair for the examiner, normal chair for the subject and a chair for the test
itself. This last chair has to be really comfortable, has to have large and
long enough armrests in order to give the subject the easiest means to sit
still during the chart recording.
Psychological research has indicated that the most
relaxing colour for the walls is with a very light hint of purple mix. This
colour seems to subdue the subject and leads easier to confessions.
2.2.3.3.2.
Question types.
In the different types of test questionnaires which
will be discussed
later, three different types of questions will be
used.
* Irrelevant questions.
Irrelevant questions are essentially questions, which
will give the examiner a truthful answer. It is generally a "Yes"
answer.
Examples:
- Is today
__________________?
- Is your
name _____________?
- Are you
sitting in a chair?
- Were you
born in _________?
The irrelevant question gives the examiner a good idea
how the subject reacts when being truthful.
It also allows the parasympathetic system to bring
back homeostasis.
* Control questions.
The control questions are questions on which all
subjects will be potentially untruthful. They are used to absorb any anxiety of
a truthful subject and draw the attention away from the relevant questions.
The control questions are so designed that they will
draw a possible lie from the subject to items broadly similar to the issue on
hand.
The reaction to the control questions will be compared
to the relevant questions in order to give a result.
Examples of control questions:
- Before
this year, did you ever steal anything in your life?
- Before
this year, did you ever lie to someone who trusted you?
- Do you
remember if you ever stole anything from a place where you
worked?
- Do you
remember ever seriously lying to any of your colleagues?
The question is typically a "No" question.
When the subject says yes to a question, which asks if he ever stole anything,
the examiner will quietly ask what he stole. Most subjects will then say,
"small things" or mention a few neglectable items. The examiner will
then rephrase:
Apart from what you told me, did you ever steal
anything else in your life?, which will then result in the desired
"No" answer.
* Relevant questions
The relevant questions are the questions of which the
examiner wants a result. These are the questions which only the subjects knows
the truth about and is the reason for undergoing the test.
The question must be phrased to engage the subject to
say "No". If for example we want to solve a dispute between X and Y
where X says she gave Y a cheque and Y says she never got it we will ask X :
- Did you
give Y the cheque we discussed?
X will say obviously say "Yes" while we want
"No".
The examiner will retract a "No" answer by
formulating the question as
follows:
- Did you
lie when you told me you gave Y the cheque we discussed?
Now we get a "No" answer.
The relevant questions are split up in 4 categories
(e.g. theft of car):
- Primary
Involvement: Did you steal that car?
- Secondary
Involvement: Did you help anybody to steal that car?
- Guilty
Knowledge: Do you know who stole that car?
- Evidence
Connecting : Did you get any reward coming from the
theft of
that car? or : Do you know where that
car is at present time?
These four different questions are called " the
four legs of the crime: " Did you do it, did you help, do you know who did
it, did you get anything out of it".
2.2.3.3.3
Type of tests.
Various and different types of test questionnaires
have been developed during the history of the polygraph. We can not go through
all different techniques but will only discuss the three most used tests as
today. Excellent documentation of all possible test questionnaires can be found
in the recommended reading list, especially S. Abrams and J. Matte.
*
MGQT.
The Modified General Question Technique ( MGQT) is a
modified version of the Reid technique developed by the famous John E. Reid in
1953.
The difference is in the strict structuring of the
test. No changes on the order of Irrelevants, controls and relevants are
allowed. It is a test adapted in most computerised scoring algorithms.
The test involves
the four legs of a crime as mentioned above.
The structure of the test is as follows:
- 1.
Irrelevant
- 2.
Irrelevant
- 3.
Relevant: Secondary involvement
- 4.
Irrelevant
- 5.
Relevant: Primary involvement
- 6.
Control
- 7.
Irrelevant
- 8.
Relevant: Guilty knowledge
- 9.
Relevant: Evidence connecting
- 10.
Control
*
ZCT
The Zone Comparison Technique stems from Baxter, one
of the great
researchers in polygraph techniques. Although
originally designed as a
S.K.Y technique (Suspicion, Knowledge, You (did you))
he later used it as a technique using three relevant questions, three controls
and four irrelevants concentrating with the relevants on only one leg of the
four legs of the crime.
The structure of the test is as follows:
- 1.
Irrelevant
- 2.
Irrelevant
- 3.
Irrelevant
- 4.
Control
- 5.
Relevant
- 6.
Control
- 7.
Relevant
- 8.
Irrelevant
- 9.
Control
- 10.
Relevant
* RANKING
In a ranking test all questions are relevant. It is
typically used to identify other people's involvement in a particular case or
to locate where the missing goods are.
It will go as follows:
- Is Mr. X
involved in this incident?
- Is Mr. Y
involved in this incident?
- Is Mr. Z
involved in this incident?
Ranking is extremely useful in investigations where
one subject has been directly linked to the crime and to find out who his/hers
accomplices can be.
Example:
An armed robbery took place at a wage pay out office
of a certain company. Thirteen staff members were present. The robbers (three)
got away with R138.000,00.
All thirteen staff members had to come for polygraph
testing regarding the involvement in the robbery (handing out information to
the robbers as to when, where, how etc.)
A ZCT test was done on all staff members.
A lady cashier was found deceptive regarding her
involvement in the armed robbery.
It was then decided to do a ranking regarding which
robber she had spoken to.
The questions were all: " Was your "brother,
sister, mother, father,
boyfriend, etc." involved in the robbery we
discussed.
The result pointed to her brother.
The next ranking's objective was to determine where
the money was being kept at that time.
The questions were: " Is the money at your "
mother's, brother's, boyfriend's, etc" house?
It again pointed to the brother's house.
The last ranking went through the brother's house:
Is the money in the " garden, garage, bathroom,
ceiling, etc." of your brother's house?
The test indicated the bathroom. After having given
this information to the police, they reported 40 minutes later that they had
indeed found the money under the bath in the bathroom of her brother's house.
Case was closed two days after the robbery took place.
* Other tests.
- Stimtest: A ranking where the person picks a card or
number and will be asked to lie when asked if he picked that certain number.
Used as a relaxation technique in pre test interviews or as a demonstration.
* Pre employment interviews
Often used for important or high-risk employment. The
technique used is Relevant/ Irrelevant whereas the irrelevant questions, when
scored as ranking, should score higher than the relevant ones.
2.2.3.4
Scoring
The actual scoring of the test is a profession. We
will not go into any detail since the investigator has to rely on the skills of
the examiner.
The computerised polygraphs use scoring algorithms.
The most renowned software is called "Polyscore" and was designed by
the "Applied Physics Laboratory" of the "Johns Hopkins
University".
2.2.4
Who uses the polygraph?
The polygraph daily becomes more and more popular in
RSA.
At present the USA, Israel, Russia and Japan are
probably the biggest users, although 77 other countries are also known as being
frequent users of the polygraph for various applications.
The polygraph is obviously mostly used in
investigations:
Crime
investigators (private or official)
Fraud
investigators, Insurance companies etc.
Another popular use is involved in pre employment
screening and honesty maintenance checks.
Attorneys often use it in civil litigation.
The private sector often requires it for matters not
involving the legal or criminal justice system.
In certain countries the polygraph is generally used
as a tool to control and check people on parole.
2.2.5
Is the polygraph admissible in court?
In certain countries and certain states of the USA,
yes.
In South Africa, no real status has been given to the
validity of a polygraph test as evidence in court.
One Magistrate's court (Booysens) once accepted (1996)
two polygraph tests as evidence, but since then no other case has been
reported, as far as the author is aware.
The CCMA at certain times ruled in favour of the
employer due to a polygraph test done on one of their employees, but rejected
the test just as often.
The polygraph test remains an investigative tool
mainly and has to be viewed purely as that.
It is our opinion that any evidence delivered in court
has to be foolproof and not one investigative tool such as truth verification
test can claim to be 100%.
2.2.6
Training available for polygraph operators.
In the RSA, training was available through a pilot
school in Midrand, but our correspondent stated that too much problems arose
about accreditations.
The University of Durban Westville is in the process
of developing a BA Honours module, which will enable BA Criminologists or
Psychologists to fully qualify as Truth Verification Experts.
In the USA several Universities offer training courses
on an academic level comparable to BA Honours.
Private institutions can be found through the APA
(American Polygraph Association) which offer Certificates at non-academic
level.
Matte (Forensic Psychophysiology using the polygraph;
1996: 671) however states that the training of polygraph should be restricted
to persons who have already obtained a degree at a minimum level of a BA.
Israel, Japan, Russia, Belgium, the Netherlands,
France, Germany and Italy all have Universities offering Polygraph
qualification at Honours or Masters level (no private colleges known to the
author).
2.3
VOICE STRESS ANALYSER (VSA).
2.3.1
Underlying principles
In 1964, Charles R. McQuiston made a new step in the
truth verification research.
The US Army desired to obtain an alternative
instrument to the polygraph with no need for direct connection to the subject's
body, one of the main disadvantages of the polygraph.
The instrument was to be "a remote lie
detector" with a concept based on recognition that emotional stress
induces measurable change into the human voice.
All VSA's rely on measuring stress-induced changes to
the "muscle micro-tremor" as displayed in involuntary changes in the
voice. These changes can be found in a tremor associated with contraction of
muscles, effecting minute oscillations at a frequency of about ten to twelve
Hertz (cycles per second).
The amplitude of these oscillations is a fiftieth or
less of that of the total contraction.
Although all muscles do exhibit this tremor, the voice
stress analyser will only take into regard those associated with the human
voice.
Since our voice transmits these tremors at the same
time as the occurrence of stress, the PSE can be used to analyse a narrative
conversation, a serious advantage over the traditional polygraph, where only
carefully timed (25 sec. interval) questions, with only strict yes or no
answers, can be used.
The basis of the PSE comes down to McQuiston's
discovery that, under stress, these tremors disappear. When a person speaks,
air is pushed from the lungs upward to the vocal cords. As a result, the vocal
cords vibrate in the frequency mentioned above (the speaker's main leading
frequency).
The air keeps flowing upward to the mouth and goes
through the tongue, teeth and lips, thereby creating the speech flow.
When a person lies, the amount of blood in the vocal
cords drops as a result of stress, so, no tremor.
In short, the VSA searches for the disappearance of
the normal tremor in a voice due to stress. This lack of tremor indicates a
lie.
2.3.2
Development of the VSA
McQuiston coined the name "voice stress
analysis" and together with two retired friends, Wilson Ford and Alan
Bell, he developed the first prototype of his "Psychological Stress
Evaluator" (PSE).
In 1970, the three of them founded "Dektor
Counterintelligence and Security, Inc."
This company brought the first PSE' s on the market
and is still one of the biggest manufacturers and suppliers of the instrument.
This instrument, applying voice stress analysis,
represented the first major advance since the introduction of the kymograph in
1920 by Keeler (" = a device that physically records motion or
pressure", i.e. the predecessor of the polygraph).
It applied a single-pen-heated wire Electrocardiogram
chart recorder to describe the changes to the micro-tremor.
For approximately 12 years, the PSE was dominant in
stress analysis, until the Verimetrics system, another invention of McQuiston,
appeared.
The Verimetrics allowed the analytical process to take
advantage of the newly developed personal computers to more conveniently and
effectively produce charts.
Shortly afterwards Charles Humble brought the "
Computer Voice Stress Analyser" (CVSA) system on the market.
The major advantage this system brought was the
ability of "real-time" analysis. The interview could now be committed
directly to the instrument, without the need of an intermediate recording on
magnetic tape.
Various adaptations, modernisations and more flexible
systems have since then been introduced such as:
*Diogenes Voice Stress Analysis System (Diogenes Group
1996)
*Truster (1997): a program on CD-ROM using a highly
sophisticated algorithm which enables the system not only to detect a state of
stress and measure its degree, but also to pinpoint the cause of the stress:
from lying, exaggeration or emotional conflict.
* Truster Pro (end of 1998): Truster Pro cannot really
be called a CVSA, but entails more. This new product will be discussed later.
2.3.3
Advantages of VSA over the Polygraph.
* The VSA can be used as a remote truth verification
tool.
* No direct connection to the subject's body, nor any
testing equipment (respiratory tubes, arm cuff, electro dermal finger cups).
* Possibility to interview the subject over the
telephone.
* Previously recorded conversations can be analysed
later.
* Normal conversation using full phrases and answers
can be used, no need for yes and no answers only, no timing of questions
necessary (in short, one can do an interview as well as an interrogation).
* The subject can be held ignorant of the fact that he
is interviewed and that his answers will be analysed (in this case the
recording nor the analysis can be used against him).
2.3.4
Disadvantages
The VSA is a relatively young instrument using a
technique, which has not been as thoroughly evaluated as the
psychophysiological data recorded by the polygraph.
The polygraph has been used for many decades and has
been a study object of many universities and government agencies all over the
world.
There is no doubt that the future will still bring
dramatic improvements and that faults will be documented (computer bugs).
The VSA analyses only one single item, namely the
tremor in the voice while the polygraph, as its name says, reads multiple
items, thoracic breathing, abdominal breathing, blood pulse, blood volume,
galvanic skin response and movement. However, the frequency and amplitude modulations
in the voice cover a broad spectrum.
2.3.5
Reliability / accuracy
As said already, not one truth verification technique
can claim to be 100% accurate.
In the past, is was commonly agreed that the polygraph
had a higher reliability in correctly indicating deception or truthfulness.
Clifton Coetzee, a well known polygraphist and voice stress annalist states in
his latest work (Truth extraction; 2000: 74) that a skilled and well trained
operator will obtain the same results with polygraph as well as with CVSA.
Several sources indicate reliability of the CVSA as
higher than 91,1%.
The effectiveness of a VSA test is based on the total system consisting of the hardware, the software and, most importantly, the