A polygraph, commonly referred to as a lie detector test, is a device used to measure an individual’s physiological responses to questions in an attempt to determine the truthfulness of their answers. Though polygraphs boast an accuracy rate of 80% to 90%, false positives remain a significant concern, which is why many courts do not admit polygraph results as evidence. This article delves into the potential reasons behind these false positives.
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Machine Error
Like all machines, polygraphs can malfunction or produce errors. They monitor various physiological changes like heart rate, blood pressure, and sweating. Any discrepancy in these readings due to machine malfunction can misrepresent an individual’s truthfulness. However, during the pretest or calibration phase, experienced examiners can often detect machine errors.
Key Causes for False Positives
1. Blood Pressure: High blood pressure or hypertension can affect the readings. Examiners must be informed about an individual’s hypertension so they can adjust their interpretation of the results.
2. Nervousness: Feeling anxious during a test can elevate physiological responses, making an innocent person appear deceitful. It’s crucial for the examiner to differentiate between nervousness and dishonesty.
3. Medications/Drugs: Some drugs, whether prescription or illegal, can affect a person’s physiological responses. Drugs for anxiety or hypertension, for example, might affect heart rate or blood pressure, potentially skewing results.
4. Pregnancy: Pregnancy increases a woman’s blood volume and heart rate, potentially causing elevated readings.
5. Illness: Being sick or on medication for illnesses can distort the readings. Moreover, coughing or sneezing during the test can affect the results.
6. Fatigue: Tiredness or sleep deprivation can cause elevated physiological responses. Therefore, individuals who haven’t rested well might get inaccurate results.
7. Incompetent Examiner: The expertise of the polygraph examiner is crucial. Mistakes during the pretest, insufficient preparation, or misinterpretation of results can lead to false positives.
Rectifying Errors
If you believe an error occurred during your polygraph test, you have several options:
- Request a Retest: Especially if you believe external factors like illness or mindset skewed the initial results.
- Seek a Second Opinion: Have an independent examiner review the records. The aim is to acquire what’s termed a ‘negative assurance.’
- File a Complaint: If you suspect the examiner was at fault, consider lodging a complaint with the appropriate agency.
In conclusion, while polygraphs can be a valuable tool in discerning truth, various factors can lead to false positives. Being aware of these factors and ensuring you’re in the best physical and mental state, paired with an experienced examiner, can help in achieving more accurate results.
The Polygraph Process and Its Reliability
A polygraph test measures physiological responses—such as blood pressure, pulse, respiration, and skin conductivity—while the subject answers a series of questions. The goal is to detect signs of stress or anxiety that might indicate deception. The test includes three types of questions:
- Relevant Questions: Directly related to the investigation.
- Control Questions: Baseline questions used to compare responses.
- Irrelevant Questions: Neutral questions to establish normal physiological readings.
Polygraph examiners, or polygraphers, analyze these physiological responses to determine if there are significant changes when the subject answers relevant questions. This process, when conducted by trained professionals, is grounded in scientific principles and can yield highly accurate results.
Addressing the Issue of False Positives
While polygraphs are generally reliable, false positives can occur. Several factors can contribute to this phenomenon:
- Nervousness: Some individuals may experience heightened anxiety during the test, leading to physiological responses that mimic those associated with deception.
- Misunderstanding Questions: If the subject does not fully understand a question, their response might trigger stress indicators.
- Medical Conditions: Certain medical conditions or medications can affect physiological responses and potentially lead to false positives.
Mitigating False Positives
Despite the potential for false positives, several measures can be taken to mitigate their occurrence and enhance the reliability of polygraph tests:
- Professional Training: Ensuring that polygraphers are thoroughly trained and certified by recognized bodies such as the American Polygraph Association (APA) is crucial. Skilled examiners are better equipped to interpret results accurately and identify potential false positives.
- Pre-Test Interviews: Conducting comprehensive pre-test interviews helps establish a baseline for the subject’s physiological responses and clarifies any misunderstandings about the questions. This step reduces the likelihood of anxiety-induced false positives.
- Use of Control Questions: Incorporating well-designed control questions allows examiners to differentiate between stress caused by the test environment and stress indicative of deception.
- Technological Advancements: Modern polygraph machines and software offer enhanced accuracy in measuring and analyzing physiological responses, further reducing the risk of false positives.
The Value of Polygraphs
Despite the potential for false positives, polygraph tests remain valuable tools for detecting deception. Their benefits include:
- Deterrence: The knowledge that polygraph tests are being used can act as a deterrent to dishonest behavior in various settings, including employment screenings and criminal investigations.
- Corroborative Evidence: Polygraph results can complement other evidence, providing additional insights that support the investigation.
- Efficient Screening: Polygraph tests enable efficient screening of individuals in sensitive positions, ensuring that only trustworthy candidates are selected.
- Investigative Aid: In criminal cases, polygraph tests can help narrow down suspects and focus investigative efforts, saving time and resources.
Conclusion
While false positives are a recognized phenomenon in polygraph testing, their occurrence can be minimized through professional training, thorough pre-test interviews, effective use of control questions, and technological advancements. Polygraph tests, when conducted and interpreted by skilled examiners, provide a reliable and valuable means of detecting deception. Their ability to deter dishonest behavior, complement other evidence, and aid in investigations underscores their importance in maintaining security and integrity in various fields. Embracing polygraphs with a commitment to best practices ensures that their benefits far outweigh the occasional drawbacks of false positives.
