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CHAPTER II

DECEPTION DETECTION

Methods of deception detection used by

law enforcement agencies:

1.Devices which record the psycho-physiological responsea.Polygraph or lie detector machine

records physiological changes that occur

in association with lying in a polygraph.

Phases of Examination

i. Pre-test interview

ii.Actual interrogation and recordingthrough the instrument

Standard test questions:1.Irrelevant questionsno bearing to

the case under investigation (ex: age,

citizenship, occupation, etc).

2.Relevant questions pertaining tothe issue under investigation (ex: Did

you shoot to death Mr. X?).

3.Control questionsunrelated to thematter under investigation but are of

similar nature although less serious

as compared to those relevant

questions (ex: Have you ever used agun?).

iii.Post-test interrogation

Supplementary tests:

i. Peak-of-tension testmay be given ifsubject is not yet informed of the

details of the offense for which he is

being interrogated by the investigator.

ii.Guilt complex testapplied when theresponse to relevant and control

questions are similar in degree and

consistency in a way that the examiner

cannot determine whether the subjectis telling the truth or not.

iii.Silent answer test conducted in the

same manner as when relevant,irrelevant and control questions are

asked, but the subject is instructed to

answer the questions silently, to

himself, without making any verbalresponse.

Factors responsible for the 25% errorsof the lie detector:1.Nervousness or extreme emotional

tension experienced by a subject who is

telling the truth regarding the offense inquestion

2.Physiological abnormalities

3.Mental abnormalities

4.Unresponsiveness in a living or guiltysubject

5.Attempt to beat the machine by

controlled breathing or by muscularflexing

6.Unobserved application of muscular

pressure which produces ambiguities

and misleading indications in the bloodpressure tracing

b.Word association test A list ofstimulus and non-stimulus words are read

to the subject who is instructed to answer

as quickly as possible. The time interval

between the words uttered by theexaminer and the answer of the subject is

recorded. The test is not concerned with

the answer, be it a yes or no. Theimportant factor is the time of response in

relation to the stimulus or non-stimulus

words.

c.Psychological stress evaluator (PSE)

detects, measures, and graphically

displays the voice modulations that wecannot hear. When a person speaks, there

are audible voice frequencies, and

superimposed on these are the inaudible

frequency modulations which areproducts of minute oscillation of the

muscles of the voice mechanism. Such

oscillations of the muscles ormicrotremor occur at the rate of 8 to 14

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cycles per second and controlled by the

central nervous system.

2.Use of drugs that try to inhibit theinhibitor

a.

Truth serum In the test, hyoscinehydrobromide is given hypodermically inrepeated doses until a state of delirium is

induced. When the proper point is

reached, the questioning begins and thesubject feels a compulsion to answer the

questions truthfully.

b.Narcoanalysis or narcosynthesis

practically the same as that ofadministration of truth serum. The only

difference is the drug used. Psychiatric

sodium amytal or sodium penthotal isadministered to the subject.

c.Intoxication the apparent stimulation

effect of alcohol is really the result of the

control mechanism of the brain, soalcohol, like truth serum, and

narcoanalytic drugs inhibit the

inhibitor. (In vino veritasin wine thereis truth)

3.Hypnotism the alteration of

consciousness and concentration in whichthe subject manifests a heightened of

suggestibility while awareness is

maintained.

4.By observation

Physiological and psychological signs andsymptoms of guilt:

a.Sweating if accompanied with a

flushed face indicate anger,

embarrassment or extreme nervousness.If with a pallid face, may indicate shock

or fear. Sweating hands indicate tension.

b.Color change flushed face may

indicate anger, embarrassment or shame.Pale face is sign of guilt.

c.Dryness of the mouthnervous tension

causes dryness of the mouth which causes

continuous swallowing and licking of the

lips.

d.Excessive activity of the Adams apple on account of dryness of the throat,

subject will swallow saliva which causes

frequent upward and downwardmovement of the Adams apple.e.Fidgeting constantly moving about in

the chair, pulling his ears, rubbing his

face, picking and tweaking the nose, etc.Indicative of nervous tension.

f.Peculiar feeling inside there is a

sensation of lightness of the head and the

subject is confused. Result of troubledconscience.

g.Swearing to the truthfulness of his

assertionI swear to God I am tellingthe truth

h.Spotless past record subject may

assert that it is not possible for him to do

anything like that inasmuch as he is areligious man and that he has a spotless

record.

i.Inability to look at the investigatorstraight in the eye because of fear

that his guilt may be seen in his eyes.

j.Not that I remember expression

resort to this expression to avoidcommitting something prejudicial to him.

5.Scientific interrogation the questioningof a person suspected of having committed

an offense or of persons who are reluctant

to make a full disclosure of information inhis possession which is pertinent to the

investigation.

Suspectperson whose guilt is consideredon reasonable ground

Witness person other than the suspect

who is requested to give information

Different types of criminal offenders

a.Based on behavioral attitude:

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i. Active aggressive offenderscommit

crimes in an impulsive manner

ii.Passive inadequate offenders commit crimes because of inducement,

promise or reward.

b.Based on the state of mindi. Rational offenders commit crimewith motive or intention

ii.Irrational offenders commit crime

without knowing the nature and qualityof his act.

c.Based on proficiency

i. Ordinary offenders engaged in

crimes which require limited skillii.Professional offenders commit

crimes which require special skills

rather than violence.d.Psychological classification

i. Emotional offenderscommit crimes

in the heat of passion, anger, or

revenge.ii.Non-emotional offenders commit

crimes for financial gain and are

usually recidivist or repeaters.

Techniques of Interrogation

a.Emotional appeal interrogator must

create a mood that is conducive toconfession

b.Mutt and Jeff techniquethere must be

at least 2 investigators with oppositecharacter; one (Mutt) who is arrogant and

relentless, and the other (Jeff) who is

friendly, sympathetic and kind.c.Bluff on split-pair technique

applicable where there are two or more

persons who allegedly participated in the

commission of a crime. While one ofthem is interrogated, the interrogator may

claim that the subject was implicated by

the author and that there is no use for him

to deny participation.d.Stern approach questions must be

answered clearly, and the interrogator

utilizes harsh language.

e.The subject is given the opportunity tomake a lengthy, time-consuming

narration.

6.Confession an expressed

acknowledgment by the accused in acriminal case of the truth of his guilt as tothe crime charged, or of some essentials

thereof.