What is polygraph test?

A polygraph test, commonly known as a lie detector test, is a tool used to measure and record various physiological indicators, such as heart rate, blood pressure, respiratory rate, and skin conductivity, while a person answers a series of questions. The underlying assumption of the polygraph test is that deceptive answers will produce physiological responses that can be differentiated from those associated with truthful answers.

How the Polygraph Test Works:

1. Pre-Test Phase:
   • The examiner explains the test process to the subject and asks baseline questions to establish a reference point for their physiological responses.
   • The subject is asked to confirm they understand the questions.
2. Questioning Phase:
   • The examiner asks a mix of relevant and control questions. Relevant questions are directly related to the issue under investigation, while control questions are general questions used to gauge the subject’s truthfulness.
   • The subject’s physiological responses are recorded during this phase.
3. Post-Test Phase:
   • The examiner analyzes the data collected to determine if there are significant differences in the physiological responses between the relevant and control questions.
   • The examiner may discuss the results with the subject.

Reliability and Criticism:

• Accuracy: Proponents claim that polygraph tests are effective in detecting deception with an accuracy rate of around 80-90%. However, the reliability of the test is highly debated.
• False Positives/Negatives: The test may produce false positives (indicating deception when the subject is truthful) or false negatives (failing to detect deception).
• Legal and Ethical Concerns: The use of polygraph tests in legal settings varies by jurisdiction. In some places, the results are not admissible in court due to concerns about their reliability.

Modern Usage:

• Polygraph tests are commonly used in criminal investigations, pre-employment screenings for certain sensitive positions (e.g., in law enforcement or intelligence agencies), and in some instances of internal investigations within organizations.