As a law enforcement officer, your main role when using Computer Voice Stress Analysis (CVSA) technology for an investigation is to ask the questions during the examination. You will also probably be involved with generating a list of potential questions prior to the actual examination. As you work through these processes, it is imperative to understand that the question formulation process for CVSA interviews is far from arbitrary.
There are three types of questions used in CVSA examinations: relevant questions, irrelevant questions, and control questions. Within each of these categories, questions are chosen for specific purposes and structured in certain ways to ensure the scientific accuracy of the results generated by the CVSA.
The Relevant Question
The relevant question is a direct query about the topic of investigation. It must be short and to the point; a yes-or-no question that requires a definitive affirmation or denial. It’s also important to avoid mentioning more than one issue in a relevant question. When CVSA technology evaluates the subject’s physiological response to a compound question, it is impossible to determine which part of the question caused the stress reaction, making the information unhelpful for the investigation. In addition, it is best to leave specific dates and times out of relevant questions, since the ones on record are often inaccurate.
For example, consider the following attempt at formulating a relevant question: “Did you steal the gun from Bob Smith and use it to shoot him on June 1st?” This is not an ideally phrased relevant question because it includes two key issues (stealing the gun and shooting the gun), as well as a specific date (June 1st).
A better way to formulate the question would be to divide the query into two separate questions:
“Did you steal the gun from Bob Smith?” And, “Did you shoot Bob Smith?” That way, if the CVSA detects stress, it will be possible to determine which question triggered the response.
Relevant questions can be divided into two categories: primary and secondary relevant questions. Both are important to the investigation, but the primary relevant question is expected to elicit a greater stress response than the secondary relevant question. Therefore, questioners must always ask the primary relevant question after the secondary relevant question. This ensures that a stress response initiated by the primary relevant question does not impact the response to the secondary relevant question.
To get a better idea of how this works in practice, consider the case from the previous example. The primary question would be, “Did you shoot Bob Smith?” while the secondary question would be, “Did you steal the gun from Bob Smith?” Both questions address critical elements of the investigation, but the one about shooting Bob Smith is expected to trigger a more powerful stress response. Therefore, it is best to ask about the theft first in order to prevent the stress triggered by the shooting question from impacting the response to the secondary question.
The Irrelevant Question
Irrelevant questions ask about known truths that should not cause stress in the interview subject. They are designed to capture carryover stress from relevant questions, so they are asked directly after relevant questions. Carryover stress refers to a prolonged or delayed physiological response to a question, recognizing the fact that, for some subjects, it can take some time for the stress response to kick in. By asking an irrelevant question after a relevant question, instead of immediately bringing up a new relevant question, examiners can attribute any stress picked up by the CVSA to that particular relevant question.
When formulating an irrelevant question, avoid asking questions that seem irrelevant and straightforward, but that may actually cause subtle stress reactions for external reasons. For instance, you might ask, “Do you attend Harvard University?” It seems like a basic yes-or-no question, but it could remind a student of a big test coming up. It is also important to avoid asking questions that may not have definitive answers. For example, asking, “Are you a man?” could lead to confusion given the expanding definition of gender and sexuality in today’s society. As a result, a stress reaction captured by the CVSA technology after the not-so-irrelevant question may not be fully attributable to the previous relevant question, which can skew the accuracy of the test results.
Often, your best bet is to ask an irrelevant question about yourself. You could ask something obvious like, “Am I wearing a hat?” or “Am I standing up?” That way, there are no subtle nuances or stress triggers within the relevant question, and any stress the CVSA picks up can be reliably considered as carryover stress from the relevant question asked before.
The Control Question
Control questions are formulated in a similar manner as irrelevant questions, except the examiner asks the subject to lie in response to the control questions. These questions do just what their name suggests; they provide a control that is used to evaluate the overall CVSA chart. Although it is not always necessary, in certain cases it can be helpful to compare the subject’s reactions when answering control questions to the response provided during relevant questions and/or the irrelevant questions that immediately follow relevant questions.
After the questioning is over, law enforcement officers look at the charts generated by the CVSA in order to detect signs of deception at specific points in the examination. If the subject is lying, there should be a significant stress present in the responses to either the relevant questions or the following irrelevant questions.
The questions for CVSA examinations are chosen based on rigorous criteria, and they are optimized for the particular investigation at hand. This ensures the reliability of the results because the answers to certain questions can be directly correlated to the physiological responses captured by the CVSA. Knowing this, you can feel confident about the conclusions you draw when using CVSA in your investigation.
Please reach out to us at NITV Federal Services to learn more about our CVSA systems and training programs.