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All About Lie Detector Tests

The majority of lie detectors are instruments which measure changes in certain areas of a person’s body in response to questions. The concept is that if an individual responds differently to specific kinds of questions, the individual can be determined either innocent or guilty. If a person’s behavior is not considered innocent or innocent, this is referred to as an inconclusive outcome.

Through the years, laboratory and field research has revealed that most liars have similar patterns of change of physical behaviour that sensors can detect. Of however, there are some instances when some liars fail to exhibit the same physical characteristics like the majority. This is why lie detectors are able to detect a margin of error.

This page will concentrate on two test to detect lies:

(1) EyeDetect(r)

(2) Polygraph

The two devices were proven by field and laboratory research to possess more than 80% accuracy in detect deceit. If a lie detector system achieves an accuracy of 80% or more the device is not appropriate for use by security-conscious businesses.

There are various methods in use today for lie detector testing, including personal interviews (lie detection by observation), integrity tests, voice stress analyzers, micro expression software, electroencephalogram, fMRI, and others.


The test for ocular motor deception (now known as EyeDetect) was originally developed around 2002, by two researchers from University of Utah. University of Utah.

It’s a computer-driven device with a high-definition tracking camera that tracks eye movements like pupil dilation eyes movements (fixations) and blink rate in tests of 15 to 30 minutes in which the test participant answers the questions using the computer mouse.

Eye behavior and test results are collected and analyzed using a computer-generated algorithm to calculate the credibility score.

EyeDetect offers many features that are similar to polygraph since its creators know polygraphs well.

EyeDetect tests are automated and standardized. They score without any involvement from a human examiner, aside from the preparation of the test. No sensors or other equipment are connected to the individual taking the test.


The instrument known as the polygraph was invented during the 20th century. In essence, it’s an instrument to record the variations in three categories of physiological activity: (1) cardiovascular activity like blood pressure and heart rate, (2) respiratory activity and (3) conductance in the skin.

The polygraph began as an analog device, but was updated in the late 1990s to be more digital that is today software-driven.

The cardiovascular activity is monitored using the same blood pressure cuff as one you’ve seen at the doctor’s office. The frequency and depth of breathing are recorded by tube-shaped sensors , which are connected to the chest and abdomen.

The conductivity of the skin, or resistance which is also known by the term electrodermal, can be measured using small electrodes attached to finger with a tiny glue as well as Velcro wraps.

A majority of polygraph examiners also come with a motion sensor to the chair that is used for testing a person. It detects small movements of the legs, trunk, and feet.

Tests based on polygraphs rely on examiners to answer questions and score tests.

Test Format

The recording of changes in physiological function as well as the responses to questions is recorded in the course of EyeDetect and polygraph tests. Both systems have the pre-test that follows by the test for lie detection. Both tests contain exercises to make the test taker familiar with the format of questions.

Note: The person who must be subjected to an examination for lying is referred to as”examinee. “examinee.”

Before testing using EyeDetect Examiners watch an audio-visual demonstration of the subject matter to be tested and is provided with instructions on “how” to be conducted.

In an exam for polygraphs an examinee receives instructions from the examiner on “how” this test is administered and the test questions are discussed to ensure that the person taking the test understands the purpose that the examination will cover.

Both tests may contain a pre-test process, referred to as an acquaintance test or stimulation. This test can be used as an opportunity to test the accuracy of the device in order to provide the user with confidence in the device.

The tests are both based on the subject matter. Check out for the “Test questions” subsection below to find more information.

Test Protocols

Two test protocol are for EyeDetect or polygraph testing: (1) screening tests and (2) tests for diagnosing.

Screening tests are that are conducted without any known incident or allegation and are of a general nature. They might ask the person being examined about a range of target behavior or may focus on an individual issue that is that is of significance. The target behaviors can include theft, use of drugs and fraud, bribery or domestic violence.

Screening tests are commonly utilized as a pre-employment test of applicants for jobs and as an additional exercise for employees currently employed.

Diagnostic tests are performed when there is an alleged incident or allegation . They include questions that are specific to an incident, like the robbery of a bank sexual assault, a bank robbery, or murder. These kinds of tests are usually employed in civil or criminal instances.

Test Questions

Tests for eye detection and polygraph contain “relevant” questions that are designed to address the target’s behavior or the issue of concern.

* Have you ever used illegal substances within the last 90 days?
Did you smuggle any cash out of your account at the 1st National Bank last week?

There are as well “comparison” questions that aren’t related to the behavior of the test subject or subject of concern. They are designed to determine an appropriate reaction in the event that the examiner is being honest or offer a different set of questions to test the test taker’s intention of passing the test.

If someone does not react strongly to questions on comparison but is able to respond strongly to the relevant questions the two systems may make a suggestion that they are lying.

Psychology of Testing

In the test for lie detectors the examinees are mostly focused on getting through the exam. If they fail the test to detect lies it could mean they be fired, but not be hired, end up in jail, divorced, etc.

A true-to-lifer will be focused on following directions and answering every question truthfully. A true-to-life person doesn’t want to be a failure on the test because of something that isn’t related to the truth.

A person who is a liar will be anxious about appearing innocent while answering the pertinent questions with only a minimal reaction to their body. Everyone is driven to be successful in passing the test.

Both tests show when there is a higher physiological response to the relevant questions than those that are posed to the comparison question the test subject is believed to be deceiving.

If an examinee exhibits an increased physiological response to the comparison question than to relevant questions, then the examiner is assumed to be harmless.

If there is no significant variation is noticed in the test taker’s response to the relevant questions and those that compare the test result may be classified as “inconclusive.” This means that the test subject’s behavior was not innocent or guilty.

Test Scoring

The tests for eye detection are scored using an algorithm developed by computers. Information about eye behavior and test results are used to calculate an acceptable score within minutes of the test’s conclusion.

Tests for polygraphs are scored by examiners who’ve received instruction in reading and interpreting the physiological responses. Polygraph instruments also rely on algorithms that aid the examiner.

Accuracy of the Test

The accuracy of both EyeDetect and Polygraph has been tested in numerous lab experiments under controlled conditions using “ground fact.” According to definition ground truth is a term that is used in research studies that reveal the exact number of lab participants are assigned to the “innocent” or “guilty” circumstance.

The guilty participants will be required to participate in a mock or simulation crime in the laboratory study, whereas those designated as innocent are not required to commit any mock crime. Both groups are examined on the same subject.

The results of lab studies for eyeDetect as well as polygraph were published in journals of science and peer-reviewed in a number of cases.

Despite the findings from scientific studies certain physiological reactions might not be exclusive for liars and truthtellers. Truthtellers can be nervous, anxious, or distracted during a test and could exhibit symptoms of an reaction that are typically experienced by those who are guilty.

If an honest person fails an examination, it is referred to as a false-positive (FP) results. If a lieder fails a test, this is known as a false negative (FN) outcome. For EyeDetect or polygraph, they is a margin of error. Both have been demonstrated to reduce FPs as well as FNs.


A few examinees attempt in an attempt to “fool” their system through employing countermeasures. Countermeasures are actions that a person takes to defy or discredit the test.

Examples of countermeasures are physical exercise, mental exercises or using drugs. Countermeasures’ purpose is to alter changes in the body in order to alter the test results.

In the instance of EyeDetect the changes in eye behavior that are observed during questions are due to an increase in cognitive load. These changes are not voluntary. They are uncontrollable.

Furthermore, the speedy time of the questions asked during the EyeDetect test makes implementing an effective countermeasure difficult.

There are various methods in use today for lie detector testing, including personal interviews (lie detection by observation), integrity tests, voice stress analyzers, micro expression software, electroencephalogram, fMRI, and others.

Other than EyeDetect and Polygraph Other methods are usually not more than 88% reliable expensive or very injurious as well as uncomfortable for test subject.