Understanding Polygraph Test Results
Results of a lie detector test are based on a numerical score, which is generated by analyzing the reactions to each question asked during the procedure. Following established scoring protocols – which will vary by exam type – the result of the exam is based on the rules for that particular testing technique.
When an APA validated testing method is used, these numerical scores translate to a probability of deception based on scientific peer-reviewed research and published studies. The scoring thresholds for a specific testing method are established as a result of this research, and are then used to make the final decision.
There are no absolutes in lie detector testing. Polygraph is a probabilistic science, which means the results are based on probabilities, which are based on research and mathematical (multinomial) calculations. A polygraph will never indicate that a person is lying or truthful, only the probability of deception to the target issue.
Standard scoring thresholds are set so that TRUTHFUL examinees will fall into the “less than 10% probability of deception” and the UNTRUTHFUL examinees will fall into the “greater than 95% probability of deception.” These are arbitrary cutoffs which are considered standard for the polygraph industry, but it should be noted that these thresholds can be changed based on a particular client’s tolerance for error. Click HERE for more information about polygraph accuracy.
For example, for a job applicant with the CIA, that 10% error limit would not be acceptable. The CIA would never accept an applicant that has a 10% probability of lying about their background, so the tolerances for error would be much smaller, and the cut scores would also be different than standard.
Standard scoring thresholds are set so that TRUTHFUL examinees will fall into the “less than 10% probability of deception” and the UNTRUTHFUL examinees will fall into the “greater than 95% probability of deception.” These are arbitrary cutoffs which are considered standard for the polygraph industry, but it should be noted that these thresholds can be changed based on a particular client’s tolerance for error.
For example, for a job applicant with the CIA, the 10% threshold would not be acceptable. The CIA would never accept an applicant that has a 10% probability of lying about their background, so the tolerances for error would be much smaller, and the cut scores would also be different than standard.
STANDARD SCORING THRESHOLDS are set so that TRUTHFUL examinees will fall into the “less than 10% probability of deception” and the UNTRUTHFUL examinees will fall into the “greater than 95% probability of deception.” These are arbitrary cutoffs which are considered standard for the polygraph industry, but it should be noted that these thresholds can be changed based on a particular client’s tolerance for error.
For example, for a job applicant with the CIA – where National security is at stake – the 10% threshold would not be acceptable. The CIA would never accept an applicant that has a 10% probability of lying about their background, so the tolerances for error would be much lower, and the cut scores would also be different than standard.
POLYGRAPH RESULTS ARE USUALLY PRESENTED USING ONE OF THE FOLLOWING TERMS
NO DECEPTION INDICATED (NDI)
When a subject’s response to a given question falls into the “truthful” range, the reactions produced are similar to those taken from actual case studies wherein test subjects were being truthful (as independently verified). The Examinee may reasonably be excluded as a suspect. This result is only used with single (specific) issue testing.
DECEPTION INDICATED (DI)
When a subject’s response to a given question falls into the “deceptive” range, the reactions produced are similar to those taken from actual case studies wherein test subjects were lying about the target issue (as independently verified). Subject can not be excluded as a suspect. Subject is likely to be withholding pertinent information regarding this issue. This result is only used with single (specific) issue testing. Click HERE to see the reasons why people fail polygraph exams.
NO SIGNIFICANT REACTIONS (NSR)
When a subject’s responses to ALL the relevant questions falls into the “truthful” range, the reactions produced are similar to those taken from actual case studies wherein test subjects were being truthful (as independently verified). Subject’s statements may reasonably be accepted. This result applies only to multiple issue or screening exams. Note that decisions using this format are not question-specific. This exam is either passed or failed as a whole.
SIGNIFICANT REACTIONS (SR)
When a subject’s response to ANY of the relevant exam questions falls into the “deceptive” range, the reactions produced are similar to those taken from actual case studies wherein test subjects were lying about one or more of the test issues. Subject can not be excluded as a suspect, or is likely to be withholding pertinent information regarding this topic. This result applies only to multiple issue or screening exams. Note that decisions using this format are not question-specific. This exam is either passed or failed as a whole. Click HERE to see the reasons why people fail polygraph exams.
INCONCLUSIVE (INC)
When a subject’s response to a given question is found to be inconclusive, a determination of truth or deception could not be made. Inconclusive results occur in less than 10% of all responses analyzed, but increase proportionately with the number of relevant questions asked in the overall examination. The most common causes of inconclusive results are:
- INSUFFICIENT REACTIONS: Reactions of the subject are too weak (below threshold levels) to produce results which can be scored. This can be the result of fatigue, legal or illegal drugs, lack of sleep, exams which are given late in the day, or the use of too many relevant questions.
- INCONSISTENT REACTIONS: Reactions of the subject are inconsistent throughout the examination. In some cases there is some reaction to the relevant questions, but in other cases there is none. For an exam to be scored conclusively there must be consistency. This situation is sometimes caused by an attempt by the subject to conceal knowledge of — or involvement in — a similar or related matter.
On a case-by-case basis it is often impossible to determine the precise cause of an inconclusive result. Frequently, retesting the subject under different (more ideal) conditions or on a more specific issue will help produce a conclusive examination.
NO OPINION (NO)
When polygraph charts (polygrams) are distorted to the point they can not be analyzed, a determination of “no opinion” must be rendered. Such distortions are most often overt (intentional) bodily movements, but may also be caused by medical disorders, coughing, sneezing, sniffling, hyperventilation and other breathing irregularities, muscle spasms or other acute nervous reactions. This result also appears when the Examinee is unable to follow all of an Examiner’s instructions. Sometimes retesting will minimize these issues, but such distortions are usually beyond the examiner’s control, and in many cases are created with the intent to interfere with the exam.
NO OPINION DUE TO COUNTERMEASURES (CM)
When an Examinee intentionally attempts to subvert the procedure by using Countermeasures, the Examiner will often recognize those attempts. Examiners are extensively trained to identify these Countermeasures, and once that happens, the test result will be “No Opinion due to suspected Countermeasures.”
This page addresses the following issues:
- Polygraph results
- Lie Detector Results
- Understanding polygraph results
- Understanding lie detector results
- Polygraph results explained
- Lie Detector results explained
- How to understand Lie Detector results
- How to understand Polygraph results
- What do polygraph results mean
- What do Lie Detector results mean