When the lie does not fly – cognitive load interview techniques to elicit intelligence

Judging the veracity of verbal statements is of high importance in all types of investigative settings, such as internal investigation of a company, the questioning of a trial witness, or the interrogation of a suspect. This post gives a brief overview of what the cognitive-based techniques of interviewing and interrogation can offer the interviewers irrespective of the type of their fields.

Hanns Joachim Scharff was an extremely successful interrogator working for the German Luftwaffe during WWII who interrogated more than 500 prisoners of war. His interrogation techniques gained wide recognition due to his unconventional, humane, and noncoercive approach. He elicited large amounts of detailed critical intelligence from his prisoners by developing a human intelligence-gathering technique that rested upon taking the prisoners' perspective that allows an individual to anticipate other people's behavior and reactions. This cognitive ability to take the perspective of others is high of importance for interrogators or anyone else in investigative settings or to anyone in negotiation settings.

Scharff was second to none when eliciting valuable human intelligence, and not every investigator possesses his set of skills. Nevertheless, even without being the master of interrogation as he was, we still can gain a lot from the scientific results on cognitive techniques for strategic interviewing that provide ample evidence that understanding our interview subjects' cognitive mechanisms can be translated into effective interview tactics. It does not matter if it is the questioning of an employee in an internal investigation or a witness in trial preparation or a suspect in a criminal investigation; cognitive science has a lot to offer.

The cognitive load approach

Beyond dispute, judging veracity is an integral part of investigative interviewing. Obtaining accurate and detailed accounts from subjects during investigative interviews can be difficult. A current focus in research is developing cognitive-load approaches (CLAs) and techniques to improve the ability to make correct judgments of credibility through the elicitation of cues to deception and truth detect deception. The CLA has based on the assumption that

lying is cognitively more demanding than truth-telling; therefore, inducing a more significant load with interview techniques will be more detrimental to liars than truth-tellers. The hypothesis is that increased cognitive load will result in more significant observational behavioral differences between truth-tellers and liars, and such differences are diagnostic of deception.

Even though the convincing and evidence-based explanations for the cognitive mechanisms involved are still lacking, there are some possible explanations for CLA's operation. Some researchers explain CLA at a neuro-cognitive level by proposing that activating event-related information in memory is detrimental to the liar but not the truth-teller. While the liar tries to manage information by suppressing leakage and creating a convincing account, for the truth-teller, the spreading of activation in memory networks facilitates the availability of helpful information to provide a convincing account.

Compared with truth-tellers, liars are slower and make more errors when responding to questions and reporting having to inhibit the truth that is automatically activated in mind.

Neuroimaging studies also support significantly greater activation of brain structures (the articulate cingulate cortex) associated with executive control processes (e.g., inhibition, attention, working memory) during lying than truth-telling.

These results might support the notion that lying is more cognitively demanding than truth-telling because of the greater need for executive control.

Other scholars explain CLA at a behavioral–cognitive level and suggest that not being honest and truthful or lying in an interview or interrogation can be more cognitively demanding than truth-telling for the following reasons:

​1. Formulating the lie in itself is cognitively demanding. If we want to lie, we have to invent a story and then monitor our fabrication to make it plausible and adhere to everything the observers know or might find out in the interview process. We also have to refrain from providing new leads for the interrogators. 2. We are typically less likely to take our credibility for granted if we lie. As a result, we will be more inclined than truth-tellers to monitor and control their demeanor to appear honest to the investigator, and such monitoring and controlling is cognitively demanding. 3. Since liars do not take credibility for granted, they may also carefully monitor the investigator’s reactions to assess whether they appear to be getting away with their lie, which also requires cognitive resources. 4. Liars may be preoccupied with the task of reminding themselves to roleplay, which requires extra cognitive effort. 5. If we lie, we also have to suppress the truth while fabricating. It is also cognitively demanding. 6. While activation of the truth often happens automatically, activation of the lie is more intentional and requires mental effort.

The reverse-order technique

There are several published studies on the effectiveness of CLA through strategic interviewing in investigative settings. The most well-known technique invented by Vrij and colleagues is the reverse-order technique.

It involves having truth-tellers and liars describe an event in reverse chronological order. The researchers hypothesized that such reverse order is an effective way to increase cognitive load and tested the effects on the interviewees in two different experiments.

They found that five stereotypical deception cues emerged as reliable differentiators of liars and truth-tellers: fewer auditory details, fewer contextual details, and more speech disturbances (speech hesitations, spoke slower, more speech errors) in accounts of the events, frequency of speech errors (stuttering, word repetition, starting over) and eye blinks.

Vrij and his colleagues also found that observers could better discriminate deceit and truth when interviewers imposed mentally taxing interventions on the interviewee.

The observers could detect

42 percent of the lies in the chronological condition;

on the other hand, they could detect

60 percent of the lies in the reverse order condition.

The unanticipated questions technique

Another well-known CLA technique to increase cognitive load is the use of unanticipated questions during interviews, such as asking participants to describe the spatial layout or temporal order of an event or to compose a drawing of the target event.

This technique is based on the presumption that liars prepare some but not all aspects of their cover story and that by asking liars unexpected questions about their cover story, their responses may be less detailed, plausible, and consistent.

Planning indeed makes lying more effortless, and if we have a planned lie, typically, it will contain fewer cues to deceit than spontaneous lies. However, any positive effects of such planning will only emerge if we can correctly anticipate the questions that will be asked during the interview or the investigation. Investigators can exploit this by asking questions that liars do not anticipate. Even though liars can refuse to answer these unanticipated questions and answer‘‘I don’t know’’ or ‘‘I can’t remember’’, such responses will create suspicion if the questions are about central (but unanticipated) aspects of the target event.

Researchers tested this CLA technique and interviewed pairs of liars and truth-tellers individually about having had lunch together at a restaurant. The truth-tellers did have lunch together; the liars did not have lunch, but they were instructed to pretend as they had. All pairs had the opportunity to prepare for the interview. The interviewer asked conventional opening questions ( ‘‘What did you do in the restaurant?’’). Questions about spatial details followed it (‘‘About where you sat, where were the closest diners?’’) and temporal details (‘‘Who finished their food first, you or your friend?’’).

Then the subjects were asked to sketch the restaurant's layout in question. The spatial questions and drawing requests surprised the subjects. The observers could not distinguish the liars and truth-tellers based on the answers to the anticipated questions (the hit rate did not exceed the chance level). However, based on the responses to the unanticipated questions,

the observers correctly classified 80% of pairs of liars and truth-tellers.

In other words, asking unanticipated questions about central topics elicited cues to deceit.

It is also noteworthy that drawings have never been used before as a lie-detection tool, but it seems that they have potential. Contrary to verbal requests, including an object within a drawing requires that object to be spatially located. The request to sketch forces the interviewee to convey spatial information. By comparison, verbally describing an object in a room can be done without indicating its spatial location. If a liar has not experienced an item in a particular location, he or she may still verbally describe the object without referring to its location to avoid the risk of misplacing it. The same strategy’ is not possible when the liars are asked to sketch. As a result, a liar may instead decide against sketching the object.

The strategic use-of-evidence technique

Hartwig and colleagues tested a technique to similar unanticipated questions called the strategic use-of-evidence (SUE) technique.

When using this CLA technique, interviewers disclose to the subjects incriminating evidence later rather than early in the interview. This strategic move ensures that subjects have difficulty managing information if they make inconsistent statements with the evidence.

The SUE technique is an interviewing framework that aims to improve the ability to make correct judgments of credibility through eliciting cues to deception and truth. This approach can help an interviewer plan, structure, and do an interview with a subject so that cues to deception may become more pronounced. The SUE technique was initially developed to plan, structure, conduct, and evaluate interviews in criminal contexts; the theoretical principles apply to interviews and interrogations in other contexts, including those in which the goal is intelligence gathering.

This approach can be helpful when investigators possess critical and possibly incriminating background information (evidence) in a case. Based on this piece of evidence or intel, the interviewers can exploit the different truth tellers' and liars' strategies by introducing the available evidence during the interview in a strategic manner.

The basic idea of the SUE technique is that both liars and truth-tellers consider an upcoming interview as a potential threat: the threatening element is the possibility that the interviewer might not believe them. The SUE approach suggests that

liars and truth-tellers employ different counter-interrogation strategies to tackle this issue and convince the interviewers to speak to their different mental states when entering an interview.

The assumption is that when the interviewers ask questions about the evidence, guilty subjects will use more avoidance strategies, while innocent suspects use more forthcoming strategies than liars. As a result, innocent suspects' accounts will be more consistent with the available evidence than guilty suspects' accounts. A guilty subject will often have unique knowledge about the event or wrongdoing in question, making it evident that they are involved if the interviewer recognizes them. As a result, the guilty subjects' main concern will be ensuring that the interviewer does not gain that knowledge. On the other hand, innocent subjects face the opposite problem; they fear that the interviewer will not learn or believe what they did at the time of the event or wrongdoing in question.

These mental states result in different counter-strategies for liars and truth-tellers:

Guilty suspects are inclined to use avoidance strategies

(in free recall, avoiding mentioning where they were at a particular time) or

denial strategies (denying having been at a particular place at a specific time when directly asked).

In contrast, innocent suspects neither avoid nor escape but are forthcoming and tell the truth as it happened.

In the SUE technique, the investigator aims to detect these counter-strategies via strategic use of the available evidence or possible incriminating information. The interviewer will presume that guilty subjects will use avoidance strategies when they ask questions about the evidence, while innocent suspects will use forthcoming strategies. As a result, innocent subjects' accounts will be more consistent with the available evidence than guilty subjects' accounts.

The purpose of SUE is to ask open questions (‘‘What did you do last Friday in the afternoon?’’) followed by specific questions (‘‘Did you or anyone else drive your car last Friday afternoon?’’) without revealing that evidence (closed-circuit TV images of the interviewee’s car driven in a specific location on that Friday afternoon). Truth tellers are likely to mention driving the car on that Friday afternoon either spontaneously or after being prompted. On the other hand, liars are unlikely to mention driving the car spontaneously or after being prompted. Of course, a denial will contradict the evidence.

Hartwig, Granhag, Strömwall, and Kronkvist (2006) experimentally tested the SUE technique. Police trainees at an academy in Sweden were trained to use some fundamental elements of the SUE technique.

The results showed that participants who had received training in the technique outperformed their untrained colleagues: 85% vs. 56% deception detection performance.

In addition, the results of a meta-analytic review in 2014 strongly support the SUE approach's predictions:

guilty subjects indeed tend to make statements that contradict the evidence, and we can amplify this tendency if we question them while they are uninformed about the evidence against them.

The summary effect sizes suggest that the late disclosure of evidence nearly doubles the magnitude of this tendency by guilty subjects.

It is noteworthy that SUE is a general interviewing framework within which we can use different specific disclosure tactics. One example is the so-called Evidence Framing Matrix which suggests that when we disclose one piece of evidence to the interview subject, two dimensions are particularly helpful in illuminating the different framing alternatives: the strength of the source of the evidence, which can vary from weak to strong and the degree of precision of the evidence, which can vary from low to high. Recent research showed that both when and how the evidence was disclosed moderated the effectiveness of the disclosure.

It was most effective to disclose the evidence late rather than early in the interview, and it was most effective when the evidence became progressively more robust and more precise.

In conclusion, the most effective way is to move from the most indirect form of framing (weak source/low specificity) to the most direct form of framing (strong source/high specificity).

​Suppose that we want to interview a subject about a meeting in a restaurant with Mr. X, the Evidence Framing Matrix works the best if we pose the questions as follows: „We have information telling us that you visited this restaurant.”, and then "We have footage showing that you had a meeting with Mr. X in this restaurant, and you were sitting at the table next to the kitchen.”

To conclude, we would like to mention that not only the subjects but the investigative interviewers themselves might be susceptible to the effects of cognitive load. Several inherent features of an interviewing setting may contribute to a cognitive load on the interviewer's side, such as the generation of questions, identifying topics to pursue, and seeking clarification from interviewees. Interviewers must actively listen to and accurately remember what the subjects are saying. They may also be required to take notes and formulate hypotheses to account for the events described. As such, interviewers must attend to multiple cognitive processes, and at the same time, they have to adhere to best practice guidance, such as building rapport and forming appropriate questions.

The results of a study from 2020 suggest that the cognitive demands required to complete an investigative interview led to an increased perceived cognitive load and harmed recall performance for mock interviewers.


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Outsmarting the Liars: Toward a Cognitive Lie Detection Approach


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