A polygraph test: Evaluating Truthfulness or Deception
A polygraph test is an investigation into the truthfulness or deception of a person's answers. The examiner evaluates the charts and scores them based on the subject's responses. These results can either indicate deception or truthfulness, or they can be inconclusive. The results are then transmitted to the client in writing, or they may be given to an interpreter if the subject wishes. The procedure is private and most examiners videotape the test to help them analyze the results.
Detecting deception in experimental simulations
In experiments involving real criminals, polygraph tests are the only reliable method of detecting deception. The polygraph measures the accuracy of the answer to questions that are relevant to the crime under investigation. The deception detection questions are formulated to ask the subjects specific, relevant questions. Their answers are compared to comparison questions centered on transgressions of a general nature. These comparison questions are introduced with a cover story that may reflect the suspect's concern that admitting to wrongdoing will negatively affect his or her credibility.
While polygraphs are highly effective in detecting deception, they are still not perfect. In addition, there are a number of false positives. A study done by the National Research Council found that only 73.8% of polygraphs were accurate, according to a report published in 2012.
Detecting deception in field settings
The accuracy of the polygraph varies considerably between different settings. Whether or not it is able to detect deception depends on a variety of factors, including the environment and the people being investigated. Often, officers who are unable to obtain a confession will reenact the incident and imitate the deceptive responses of a suspected suspect. The lack of realism makes it difficult to generalize the results of the polygraph to other settings.
The limitations of polygraphs and interviews must be understood by law enforcement officers. Deception cannot be detected by chance alone and cannot be reliably confirmed unless all the relevant information is known. Investigators are looking for cues that indicate discomfort or a lack of confidence. The person may be under stress for an unspecified issue, so interviewers must be cautious when pursuing a suspect. Detecting deception is not a foolproof process, so officers must exercise caution when applying the polygraph in a field setting.
Limitations of the polygraph test
There are some limitations to polygraph tests, and some are largely unknown. The most prominent of these limitations is the subject's gender. Research has shown that females and males have different autonomic arousal patterns, which could affect the validity of polygraph tests. Unfortunately, few studies have been conducted to determine how well polygraph tests can detect these differences. However, one study in particular, conducted by Cutrow et al. (45), did address this issue. In this study, they found that the guilty knowledge test was highly accurate for female subjects, while the test was highly inaccurate for male subjects.
While there are many new applications for the polygraph, their scientific foundation is a bit shaky. While the Daubert decision hasn't made much of an impact on polygraph evidence exclusion, the Cordoba decision has required trial courts to evaluate polygraph evidence with more particularity. The decision cites the high error rate and lack of standards for the test's administration. But the majority of trials still exclude polygraph evidence.
Complaints about the test
The Department of Homeland Security Office of Inspector General (DHS OIG) conducted an audit of the CBP polygraph and complaints process. The audit examined the polygraph requirements from 2010 and the effectiveness of CBP's processes to ensure accuracy. The polygraph itself is performed in three stages, the final one being the review by quality control personnel. Complaints about the polygraph process should be directed to the appropriate agency. To ensure accuracy, the polygraph test must be administered at a time that is convenient for the individual undergoing the test.
The process used to administer the polygraph test for CBP agents includes a pre-test interview, testing equipment, screening questions about illegal drugs, and national security. Post-test interviews are also required. Of the approximately 130 complaints filed against CBP polygraphs, six are backed up by audio recordings. However, if you are considering a polygraph test for employment, here are some tips to ensure a positive experience.
