Polygraph

• LIE DETECTION


  Polygraphy test, the practice of determining whether someone is lying, one of the scientific methods in crime detection
• POLYGRAPH


  popularly referred to as lie detector, always one of the scientific instruments in the detection of crime in criminal investigation department in all police organizations
• Polygraph

  literally means “many writings”

  derived from two Greek words “Poly (which means many)” and “Graphos (which means writing)”
• Polygraph 


  used to test or question individuals for the purpose of detecting deception or verifying truth of statement through a visual, permanent and simultaneous recording of a person’s cardiovascular and respiratory pattern as a minimum instrumentation requirement
• Polygraph

  measures and records several psychological indices such as blood pressure, pulse, respiration and skin conductivity while the subject is asked and answers a series of questions
• PHYSIOLOGICAL RESPONSES OF LYING

  changes in blood pressure, pulse rate, breathing and sweat activity; the instrument merely measures certain identifiable physical reactions as affecting the respiratory rate, blood pressure/pulse rate and galvanic skin resistance to a very minute amount of current in connection with the reliable questioning technique for diagnosing deception
• Blood pressure 


  the pressure exerted by circulating blood upon the walls of blood vessels and one of the principal vital signs
• PULSE OR PULSE RATE 


  represents the tactile arterial palpitation of the heartbeat by trained fingertips ; it can also be measured by listening to the heart directly using a stethoscope
• RESPIRATION OR BREATHING 


  the transport of oxygen from the outside air to the cells within tissues and the transport of carbon dioxide in the opposite direction
• Skin conductivity 


  also known as galvanic skin response ; is a method of measuring the electrical conductance of the skin which varies with its moisture level
• Lie

  any untruthful statement ; anything that deceives or creates false impression ; untrue statements especially with intent to deceive or to give an erroneous or misleading impression
• white lie or benign lie


  these are the kind of lies used to protect relationship or friendship
• pathological lie


  this is a lie who cannot distinguish right from wrong
• red lie 


  this involves political interests and motives because this is a part of communist propaganda strategy and is prevalent in communist countries
• black lie 


  a lie which accompanies pretentions and hypocrisies, intriguing to cause dishonor or discredit ones good image
• malicious or judicial lie


  this is very pure and justifiable kind of lie that is intended to mislead or obstruct justice
• fabrication

  a lie told when someone submits a statement as truth, without knowing for certain whether or not it is actually true
• bold face lie


  is one which is told when it is obvious to all concerned that is a lie
• lying by omission


  one lies by omission by omitting an important fact, deliberately leaving another person with a misrepresentation
• emergency lie 


  is strategic lie when the truth may not be told because it may harm a third party
• Perjury


  the act of lying verifiably false statements on a material matter under oath or affirmation in a court of law or in any of various sworn statements in writing
• panic liar


  one lies in order to avoid the consequences of a confession, they are afraid of embarrassment and it is serious blow to their ego; they believe that confession will just make the matter worst
• occupational liars 


  are practical liars and lies when it has a higher “pay off” than telling the truth
• psychopathic liar


  the most difficult type, these persons have no conscience and shows no regret for dishonesty and no manifestation of guilt
• ethnological liars


  are persons who cannot distinguish right from wrong due to their sick mind
• Written psychological tests, psychological or psychiatric interviews, personal interviews, and interviews by a selection board

  Considered to be less useful than polygraph screening
• EPPA does not affect public employers such as police agencies or other governmental institutions
• Reasons for using polygraph screening in police agencies

  1. It reveals information that cannot be obtained by other means

  2. It makes it easier to establish background information

  3. It deters undesirable applicants

  4. It is faster than other methods of selection
• Polygraph screening revealed applicant's involvement in serious, undetected criminality
• Background investigation

  Considered to be as useful as polygraph screening
• Applicant's involvement in serious, undetected criminality

  • 9% detected involvement in unsolved homicides
  • 34% indicated involvement in forcible rape
  • 38% showed participation in armed robberies
  • Other serious, unsolved crimes such as burglary, arson, and drug offenses were also revealed through polygraph screening
• Benefits of using polygraph screening in police agencies

  1. Applications were more honestly completed

  2. Higher quality employees were hired

  3. Fewer undesirable employees

  4. Over 90% of these agencies expressed either moderate or high confidence in their polygraph screening program

  5. 80% of them reported that the accuracy of the testing ranged between 86%-100%
• Polygraph testing had reportedly been used for the purpose of police applicant screening since at least the early 1950s