Polygraphs have been controversial tools in law enforcement and national security for nearly a century. Polygraph results are not usually admissible in court due to reliability and accuracy concerns. Critics argue polygraphs can be easily manipulated and are valuable investigative tools.
Role of stress
Being accused of wrongdoing and facing a polygraph is an extremely stressful and anxiety-producing experience. The elevated stress response alone mimics signs of deception in an innocent person. Things like increased heart rate, sweaty palms, and rapid breathing are normal when we feel threatened or anxious. In a Catch-22 scenario, the physical manifestations of stress during the polygraph incorrectly point to dishonesty, when in fact the person is nervous simply due to the pressure of being tested. An American Psychological Association report on polygraph accuracy concluded that “An innocent person who is afraid of being falsely accused anxious when answering truthfully and that anxiety difficult to distinguish from the anxiety caused by deception.”
Certain medical conditions also interfere with polygraph testing. For example, heart patients take medications that affect blood pressure and heart rate. It alters physiological responses assessed by the polygraph. Respiratory disorders such as asthma and emphysema also alter normal breathing patterns. Mental health issues can also contribute. Disorders associated with high anxiety like PTSD, panic disorders, or phobias skew test results. Polygraph examiners attempt to take medical conditions into account by reviewing a person’s medical history beforehand. But some situations like short-term illnesses go unreported and still affect results. Critics argue that polygraph administrators lack proper medical training in accounting for these influences.
Mental health and medications
Mental health disorders involving high anxiety or paranoia predispose individuals to appear deceptive on tests, even when answering truthfully. Disorders that affect thinking and perception like schizophrenia also complicate assessments of truth-telling. Many medications used to treat mental health conditions further complicate polygraph results. Blood pressure medications, anti-anxiety drugs, antidepressants, and antipsychotics all directly impact the physiological processes measured during polygraph exams. Critics point out that innocent people taking psychiatric medications or experiencing psychiatric symptoms end up at higher risk for false positive results. The National Research Council has cautioned that polygraph testing is likely to result in “unacceptable numbers of innocent subjects being falsely identified as deceptive”. For more info, visit lie detector test locations across USA.
Can polygraph testing be improved?
Polygraph experts continue working to enhance accuracy and account for the many variables that affect results. It includes better pre-test interviewing, a careful review of medical history, specialized training to detect countermeasures, and the introduction of computerized polygraph systems thought to be less subjective in measurement. However, fundamental questions remain about whether such efforts adequately control for the range of factors that incorrectly skew outcomes.
The National Research Council concluded that polygraph testing yields inaccurate results 30% of the time or more. Others put error rates even higher. Given such concerns, debate continues over whether polygraphs merit a role in the criminal justice system and law enforcement. Rather than lie detection, experts say polygraph analysis works best as an investigative aid alongside other approaches. Viewing polygraph results as just one data point avoids overreliance on a metric with inherent limitations. In light of the many variables that skew accuracy, polygraph results must be interpreted with ample caution and healthy skepticism.