Polygraph examiners attempt to detect deception by looking for exceptional recordings on a subject’s polygraph charts. Hence, questioning techniques generally involve comparing physiological responses between answers from baseline questions (control questions) and answers from core interview questions (relevant questions).
There are various questioning techniques and they generally vary in the arrangement of the questions and the choice of the questions themselves.
These are general recommendations for formulating test questions for polygraph examination:
- Questions must be simple and direct.
- They must not involve legal terminology, e.g. rape, murder, etc.
- They must be answerable by yes or no.
- They must be as short as possible.
- They must be clear, unmistakable, and phrased in a language that the subject can easily understand.
- They must not be in the form of accusations.
- They must not contain any interference which presupposes knowledge on the part of the subject.
- They must refer to one offense only.
- They must refer to only one element of the offense.
- They must not contain inferences to one’s religion, race, or belief.
Types of Questions
These are the kinds of questions that may be included in a set of questions given to a subject.
- Relevant Questions These are questions that are directly related to the case under investigation. They may also be called leaded or material questions. When a polygraph examination is used during pre-employment screening, relevant questions may include that of the subject’s background. (Example: Do you know who killed A?)
- Strong or Primary Relevant Questions These have an intense connection to the incident or issue being considered.
- Weak or Secondary Relevant Questions These questions deal with the elements of the crime and are generally about some guilty knowledge or partial involvement.
- Sacrifice Relevant or DYAT (Do You Intend to Answer Truthfully) Questions Used to attempt to determine truthfulness on the part of the subject
- Knowledge Questions Asked for the purpose of determining information known to the subject
- Evidence Connecting Questions Designed to link the subject to the crime
- Control Questions Also called, comparison questions, these are used to establish the baseline responses of the subject so that comparisons can be made later. These questions are unrelated to the incident under investigation, but are of a similar nature. They are less serious compared to relevant questions. (Example: Have you ever killed anyone?)
- Primary Control Questions Recalls offenses done from childhood up to three or five years
- Secondary Control Questions These questions may include in its scope up to the present period of examination
- Irrelevant Questions As the name implies, these questions have no bearing nor connection to the case under investigation. They are also called unleaded or immaterial. They are also believed to have no or very little emotional impact on the subject. (Example: Is today Sunday?)
Types of Test
The polygraph examination generally starts with a pre-test interview. More on the phases of the polygraph examination will be discussed in the next lesson, but you could say that the examination actually begins during this first phase. During this time, the examiner will already be making observations on the subject’s behavior, and they may use those observations during the test proper later.
- Relevant-Irrelevant Test As its name implies, this test format compares the subject’s responses to relevant and irrelevant questions. Irrelevant questions are usually placed as the first question to help make succeeding questions more valuable. They are also placed at other points in the question set. Guilty subjects are expected to react more strongly to relevant questions, while innocent subjects are expected to react the same way on every question in the set.
- Comparison Question (Control Question) Test This is similar to the previous test, except it uses comparison or control questions instead of irrelevant questions. These control questions are believed to result in specific responses from innocent subjects. There are two types of comparison question test: probable-list comparison question test and directed-lie test. In both of these types of comparison tests, innocent subjects are expected to react more strongly to comparison questions while guilty subjects are expected to react more strongly to the relevant questions.
- Probable-Lie Comparison Question Test Innocent subjects are expected to answer in the negative, even though most would be lying. Regardless, if they are innocent, they will be concerned about these answers and this concern will show in their graphs.
- Directed-Lie Tests Subjects are instructed to respond negatively and untruthfully
- Reid Comparison Question Test This is also called the modified general question test. It includes probable lie comparison questions and is interpreted by combining evaluations of the charts with other observations made by the examiner during their interaction with the subject.
- Zone Comparison Test In this test, questions are arranged thus: relevant questions (called the red zone), probable-lie comparison questions (green zone), and other questions (black zone). Black zone questions are meant for discovery of other concerns that a subject might have about an issue outside the red and green zones such as involvement in a separate crime. These zones are designed so that each zone is threatening to someone, but one will be more threatening than the others depending on the subject’s state of mind.
- Utah Probable-Lie Test In this test, the examination is constructed with question modules, typically consisting of irrelevant, probable-lie comparison, and relevant questions. The key to this test is that the examination is conducted professionally and objectively, in the style of a psychological interview instead of an interrogation.
- Utah Directed-Lie Test This test is administered similarly to the Utah Probable-Lie Test, except that the examinee is told that anyone who gives a negative answer would be lying and is then asked to give a negative answer.
- Test of Espionage and Sabotage It is a directed-lie test that was developed at the US Department of Defense Polygraph Institute. It consists of a repeated series of relevant and directed-lie comparison questions and is scored on a seven-position scoring system. There is a given predefined numerical threshold used for judging whether or not a test result includes a significant response that could indicate deception or is non-conclusive. If there is significance, further testing or further questioning normally follows.
- Stimulation Test Sometimes called the stim test or acquaintance test, examinees are presented with a question set of similar items and directed to lie about one, e.g. picking a card in a series of card, then directed to lie about having picked any of the cards. This is generally used during pretest or in between charts. The main purpose of this test is to stimulate the subject into believing that the machine can truly detect deception.
- Concealed Information Test More often called guilty knowledge or concealed knowledge test, examinees are presented a very similar set of questions, just like in the stim test, except that the similar items include one true and several (usually, four) false details of some aspect of the incident. Guilty subjects are expected to reveal their concealed knowledge by responding more strongly to the true item compared to the others.
- Peak-of-Tension Test It is similar in format to the concealed information test, but is distinct in that the similar questions are asked in a clearly defined order, e.g. Did you steal 10,00? 100,000? 1,000,000? A guilty subject is expected to have a rise in response as the questions get closer to the truth and relaxed when it has passed. It can be used to probe a subject when an examiner does not know actual values in an incident. The pattern of responses is expected to reveal the correct answer.