Polygraph
Components of the in-test phase
-Final review of questions -demonstration exam to adjust the instrument to subject's homeostasis, which will relax the truthful and stimulate the deceptive subject -data collection (charts recorded, usually 5 charts per person). -Upon completion the examiner evaluates the results which usually takes 10-15 min -Quiet/suitable environment important as it sounds etc. can produce emotional responses
What are the most common results from a polygraph
1.Truthful of No Deception Indicated: The subject was telling the truth in relation to the issue crime relevant questions 2.Deception Indicated: The subject was not telling the truth (was lying) in relation to the relevant questions 3.Inconclusive: based upon the recorded physiology, the examiner is unable to render an opinion as to truthfulness; in such cases, a subject must be retested at a later date 1 in 6 fail polygraph
What is the duration the in-test phase
15-20 mins
How long is a polygraph test
2-3 hours spent with people to establish baseline and make them less nervous
What is the duration of the pre-test phase
45-60 min but varies depending on the subject or the case
Single issue/Direct involvement ?
Control Question test, Baxter test compares responses to "relevant" questions, "Did you shoot your wife? with those of "control" questions Have you ever betrayed anyone who trusted you?" person who is telling the truth is assumed to fear control questions more than relevant questions because questions past truthfulness. if did not commit crime, relevant questions not threatening Example: On July 1, 2008, did you take that missing money, The question will be asked three times and will either proceed or follow the control question
What are the types of polygraph tests
Each test or exam is done a minimum of 3 times in order to record sufficient data for evaluation purposes Numerical scoring systems are used -Single issue/direct involvement -Mixed issue -Statement -Peak of tension/guilty knowledge test -Pre-employment screening test
Pre-employment screening test?
Form similar to the Relevant/Irrelevant Test Weed out persons who employ for police force
What is the difference in polygraph training between the USA and Canada
Many polygraph schools in USA but only one in Canada- all polygraph examiners are trained the same way/meet certain standards- increases validity and reliability
Identify and explain 3 major problems with using a polygraph to detect deception
Need a baseline, hard to get that sometimes, what if the person is nervous to begin with, you will not get a baseline. High false positive = innocent people can get nervous (increases GSR), when asked a question related to the crime as they think they can go to jail for that, this leads to many innocent people failing the polygraph test. Investigator bias = can intimidate innocent people. High false negative = professional liars can easily beat the polygraph test
What is the role of The American Polygraph Association/Canadian Association of Police Polygraph
Oversees the training, education, polygraph schools, quality controlo of virtually all Law Enforcement Polygraph Examiners in the (Western) World, including Police, Military, Intelligence Agencies, Anti-Terrorism Investigators, Customs personnel etc. Any member not conforming to professional standards of practice quality control, mandatory annual training, ethics. Will have their accreditation revoked.
What is the purpose of the pre-test phase
Relax the subject Determine suitability Establish understanding and rapport- if they like you they will feel more comfortable and will trust you more to tell you everything
What are the rules of polygraphs in court
Results of polygraph not admissible in court- it is a pseudo-science but courts will rely on expert testimony of the person who had administered the polygraph on the interview they had with the person after the polygraph Judge makes the decision whether expert testimony is admissible
Statement test
Statement: A subject can be tested on the veracity of a statement provided Example: in your statement were you lying to the investigators?
Who are the governing bodies and who oversees Quality control
The American Polygraph Association/Canadian Association of Police Polygraph
What does a polygraph test measure
The Psycho-Physiology of Deception •Respiration- breathing is measured and monitored with tubes placed around upper and lower torso •Galvanic Skin Response- also known as electro-dermal activity and most commonly sweat gland activity Use-Gel pads placed on palm- use gel pads can't compress to create different responses Silver spoons on finger tips can't compress to change responses • Cardio Vascular Activity- subjects blood pressure is monitored via a cardio cuff placed on the upper arm-Cannot control heart to try to be deceptive •Motion- subject is seated on a motion- sensing pad to ensure that they remain still during the examination and to detect countermeasures o Motion sensor pads - if you bite your tongue, if you squeeze your butt cheeks - then the motion sensor goes off - thus limiting ability to manipulate the polygraph readings
What Creates Useful Physiology What is the principle mechanism driving the polygraph
The principle mechanism or engine driving the polygraph is the fight or flight syndrome -when you lie, your body system responds, - heart beats quicker which you have no control over-flight or fight response takes place
What are the 3 phases of a polygraph test
pre-test in-test post-test
What were the 5 behavioural observation questions used by Detective Sergeant Steve Coburn when interviewing the two suspects
Thoughts and feelings on how Ms Nickles was murdered What kind of person would do something like that What should happen to person(s)/be the consequence Do they deserve the second chance Who can you exclude as a suspect involved What would be worse fear if they found out you were involved
When should a polygraph be considered
all other avenues of investigating a person's veracity have been exhausted and there are no further means of corroborating or refuting their claim Polygraph is not a solution to an investigation and should never replace accepted conventional investigative techniques. The reason, primarily, is the credibility of the witness Polygraph ought not be used as a matter of course but rather as a tool when all other have been tried unsuccessfully
What are some reasons for a polygraph test
alleged victims of crimes to take a polygraph test to verify whether a crime has occurred suspect to take a polygraph test as a means to resolve the case.
What are the components of the post-test phase
discusses the results with the subject and may interrogate the issue at hand (this is the time when they fail the test, at this time they may ask to stop the process, they are free to leave at any time, it is a voluntary process)
Peak of tension test/guilty knowledge test
do this on the onset of the investigation, before the details become known by the public multiple-choice test with items concerning knowledge that only a guilty subject could have. A test of a theft suspect might, for example, involve questions such as "Was $500, $1,000, or $5,000 stolen?" only a guilty person would know answer
What information is gathered in the pre-test phase
legal rights -10 min, understanding the right is more important than explaining the right medical and psychological history- individuals with mental issues or who are suicidal not tested -will not test hell's angel who stole $50 but will test a treasurer in a church because it questions integrity family background- help establish rapport knowledge of investigation, how the instrument works question formulation
What is usually done in the question formulation component
questions made together, builds questions with person being tested reduces anxiety remove children's name as it can evoke emotional responses suggestive questions are also not asked as it provokes emotions, anxiety
What Creates Useful Physiology What are the 6 principles of persuasion
reciprocity-obligation to give when you receive be the first to give- ensure what you give is personalized scarcity- the less/uncommon/rare there is of something, the more valuable it is tell persons what they stand to lose if they don't take it into consideration Authority-appearance of authority actually increases the likelihood that others will comply with requests - even if their authority is illegitimate. Consistency- Like to be consistent with things they have previously said or done more likely to do something after we've agreed to it verbally or in writing Liking-like people who are similar, pay compliments, physically attractive Consensus /social proof- look to actions and behaviors of others to guide our actions and decisions especially when uncertain
Mixed issue test
referred to as a knowledge or involvement examination Example: Concerning Joe, did you know he was going to be shot before it happened? Last fall, were you present when joe was killed?