Polygraphs, commonly known as lie indicator tests, are routinely used in criminal investigations and during security showings since their inception numerous decades ago. Tests are made to evaluate physiological responses that could reveal deception. So, with an understanding of what lie detectors uk do and how they measure that information, you should be able to grasp a better idea about when tokens are useful or not.
How lie detectors work?
The basic idea behind a lie sensor test is that misleading behavior, no matter how subtle, can cause some physiological changes. The changes are measured using sensors that are affixed to the body through a polygraph machine. A polygraph test is then administered and set up to measure these physiological responses in response to the questions asked of the subject.
What lie detectors measure?
- Heart Rate: It uses a ‘Polygraph’ to measure the rate of heart using sensors on the chest. Most likely, deception induces a heart rate change due to the stress or anxiety associated with lying.
- Blood Pressure: Measurements are acquired using a cuff (upper arm). Not the same as heart rate but altered blood pressure may signal lying or anxiety, which can be related to deceptive responses.
- Respiration: Continuous monitoring of breath rates and patterns using chest or abdominal electrodes. Irregular breathing is a sign of stress or nervousness that can indicate dishonesty.
How to Interpret Polygraph Results?
A polygraph test just records the physiological data and it takes a certified professional expert to interpret them. These are used to monitor changes from base measurements gathered on control questions. In response to their critical questions, substantial changes in heart rate, blood pressure or respiration could indicate stress or deception. It is worth bearing in mind that the polygraph, while useful and accurate, does have its limitations.
Problems and Implications
While polygraph testing is not perfect the subject’s anxiety, some medical conditions and even the skill of the examiner may sway the results. In addition, physiological responses can be perturbed by countermeasures—techniques intentionally used to change physiological perception—which may reduce the efficacy of PHQ or other performance measures.
Although polygraph testing is still a robust and useful tool in many investigative and security environments, including in settings like those involvinglie detectors uk, knowing what it is they test and measure can provide some insight into their value and utility for specific groups. Polygraphs should only be used as part of an overall assessment strategy and not in isolation.