In the realm of polygraph testing, particularly within comparison question tests, the formulation of questions plays a critical role in determining the effectiveness and reliability of the examinations. Traditionally, questions focused purely on behavior have been favored to avoid the complexities of assessing mental states or motivations. However, evolving practices and insights suggest that incorporating some elements of mental state can sometimes enhance the utility of polygraph tests in criminal investigations.

The Traditional Approach: Behavioral Descriptions

The fundamental principle in formulating polygraph questions has been to focus on direct behaviors related to the crime under investigation. This approach is predicated on the idea that simple, behaviorally descriptive questions are less likely to be misinterpreted and can be more objectively analyzed. For instance, instead of asking about an examinee’s intent or feelings during an act, questions traditionally would focus solely on the act itself, such as whether or not the examinee committed a specific action.

The Challenge of Mental States and Motivations

Incorporating mental states, such as intent or memory, into polygraph questions has been contentious. Critics argue that terms like “mens rea” (guilty mind) and “actus reus” (guilty act) introduce subjective elements that can complicate the interpretation of polygraph results. The concern is that mental states are inherently more difficult to assess accurately through physiological responses compared to straightforward behavioral acts.

Case Studies and Exceptions

However, there are circumstances where ignoring mental states can limit the effectiveness of a polygraph test. For example, in cases involving alleged sexual assaults where intoxication or unconsciousness of the victim is claimed, understanding the suspect’s perception and memory of the event becomes crucial. Questions such as “Did you perceive the other person to be awake and responsive during the event?” directly address the suspect’s mental state but are vital for assessing the situation accurately.

The Balance in Question Formulation

The challenge for polygraph examiners is to strike a balance between behaviorally descriptive questions and those that address relevant mental states without leading to confusion or subjective interpretations. While it is essential to avoid over-psychologizing or attributing motivations without clear evidence, completely disregarding mental states can sometimes omit crucial aspects of the truth-seeking process.

Guidelines and Best Practices

Standards and guidelines, such as those from the American Association of Police Polygraphists (AAPP) or the American Polygraph Association (APA), do not prohibit questions about mental states outright. They recognize that in specific contexts, especially post-admission testing, such questions can be crucial. The key is that these questions should be used judiciously and in contexts where they can provide meaningful insights that are not obtainable through behavioral questions alone.


The art and science of question formulation in polygraph testing continue to evolve. While the reliance on behaviorally descriptive questions has served the field well, the nuanced inclusion of mental state questions in certain scenarios can enhance the investigative process. Polygraph examiners must remain flexible, informed, and prudent in their question design to ensure that they continue to uphold the integrity and efficacy of their examinations. This balanced approach not only aligns with legal standards but also supports the broader goal of truth verification in the justice system.

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