Case File 065 · Investigation and Psychology

What Is Cognitive Load in an Interrogation?

What cognitive load means in interview research, what the cognitive approach to lie detection proposes, and where the evidence is disputed.

By Murder Book Editorial TeamPublished 16 September 2026Updated 16 September 2026

Cognitive load is the amount of mental effort a task demands. In interview and interrogation research, the term is linked to a "cognitive approach to lie detection" developed by Aldert Vrij and colleagues. Its core idea is that lying can be more mentally demanding than telling the truth, so questioning that makes an interview harder should affect liars more than truth tellers and make differences between them easier to see. Techniques studied include asking people to recall events in reverse order, encouraging them to say more, and asking questions they did not expect. A 2017 meta-analysis reported better accuracy with this approach than with standard interviews in experiments. Other researchers argue the benefit has been overstated. Either way, it is a research framework for improving interviews, not a way to read a lie from a single reaction.

Key takeaways

Cognitive load means mental effort; the cognitive approach assumes lying often takes more of it than truth telling.
Vrij and colleagues proposed imposing cognitive load and strategic questioning as two ways to use this idea.
A 2017 meta-analysis reported 71% overall accuracy for the cognitive approach, compared with 56% for standard approaches.
A re-analysis argued the advantage was much smaller than claimed, and the theory is still debated.
Stress, memory problems and vulnerability also raise mental load, so struggling under questioning is not proof of lying.

What does cognitive load mean in an interview?

Everyone in an interview is doing mental work. They are remembering, deciding what matters, putting events into words and monitoring how they come across. Cognitive load is the total of that effort compared with the mental resources available.

The cognitive approach to lie detection starts from a hypothesis: a person who is lying may have extra work to do. A 2023 review by David Neequaye in Collabra: Psychology gives an example of the reasoning researchers use: liars must suppress the truth while lying, and this handicap makes lying challenging. The theory predicts that if an interview adds further demands, a liar will have fewer mental reserves left, and signs of that strain may become more visible.

That prediction is the foundation for everything else in this article, and it is also where the debate begins.

What did Vrij and colleagues propose?

In a 2011 article in Current Directions in Psychological Science, "Outsmarting the liars", Aldert Vrij, Pär Anders Granhag, Samantha Mann and Sharon Leal started from a well-established problem: decades of research show people's ability to detect deception by observing behaviour is limited, because cues to deception are typically faint and unreliable. (The article Why There Is No Single Reliable Sign of Deception explains that research.)

Their response was to shift attention from watching to asking. The aim was to use questions that actively elicit and amplify differences between liars and truth tellers. They described two approaches:

Imposing cognitive load. Making the interview setting more difficult for the interviewee. The authors argued this affects liars more than truth tellers, producing more, and more blatant, cues to deceit.
Strategic questioning. Examining ways of questioning that produce the most different responses from truth tellers and liars.

This fits a conclusion from a separate 2011 meta-analysis by Maria Hartwig and Charles Bond: lie detection is more readily improved by increasing behavioural differences between liars and truth tellers than by teaching observers which cues to look for.

What is the reverse-order recall study?

One of the best-known experiments behind the approach was published in Law and Human Behavior in 2008 by Vrij, Mann, Fisher, Leal, Milne and Bull.

Experiment 1: 80 mock suspects either told the truth or lied about a staged event. Some described it in normal chronological order and others in reverse order. The reverse-order interviews contained many more cues to deceit than the control interviews.
Experiment 2: 55 police officers watched a selection of the videotaped interviews and judged who was lying. Asking suspects to tell their stories in reverse order improved the officers' ability to detect deception, and did not make them more likely to call people liars overall.

Recalling events backwards is harder than telling them in the order they happened. The study tested whether that added difficulty would widen the gap between liars and truth tellers, and in this experiment it did.

What did the 2017 meta-analysis find?

In 2017, Vrij, Ronald Fisher and Hartmut Blank published a meta-analysis of the cognitive approach in Legal and Criminological Psychology. They grouped it into three techniques:

imposing cognitive load;
encouraging interviewees to say more;
asking unexpected questions.

The analysis included 14 studies that directly compared the cognitive approach with a standard approach.

Measure	Cognitive approach	Standard approach
Truth detection	67%	57%
Lie detection	67%	47%
Total accuracy	71%	56%

The authors concluded that practitioners may find a cognitive lie detection approach useful in their daily practice.

Why do some researchers disagree?

The approach has attracted serious criticism. In 2018, Timothy Levine, J. Pete Blair and Christopher Carpenter published a re-analysis of the same meta-analysis in the same journal. They argued that the original analyses confounded different outcome measures, relied on unusually low accuracy in some control conditions, and drew their strongest support from the least reliable data. Their conclusion was that the advantage of the cognitive approach was much smaller than previously claimed and that the evidence had been overstated. Vrij and colleagues published a reply defending their main results, so the disagreement is ongoing.

There are theoretical questions too. Neequaye's 2023 review examined seven justifications for the idea that imposing load can expose lies. It concluded that how well each justification holds up is variable and unknown, which makes it hard to test the hypothesis rigorously, and it proposed research questions to address that.

A fair summary is that the cognitive approach is a promising and influential research programme, but its practical benefit and its theoretical basis are still being argued over.

Why is struggling under questioning not proof of lying?

Even supporters of the approach describe differences between groups in controlled experiments, not a test that works on any individual. Several innocent factors also increase mental load:

Stress. Being questioned about something serious is demanding for anyone. See How Stress Affects Testimony.
Memory. Honest people may struggle to recall details, especially out of order or long after the event. See Why Memory Is Not a Perfect Recording.
Vulnerability. Age, learning difficulties, mental health conditions or language barriers can make any interview harder. UK police guidance notes that vulnerable people and children may be more suggestible and require special protection.
Fatigue and setting. Long interviews and unfamiliar, formal rooms add strain for everyone.

Research on false confessions shows why caution matters. Treating visible strain as a sign of guilt risks the same problem discussed in Why Innocent People Sometimes Confess: a presumption of guilt that shapes everything that follows.

How does cognitive load relate to other interview methods?

The cognitive approach belongs to the wider shift from accusatory interrogation towards information-gathering interviews. It relies on getting people to talk, then examining what they say, rather than on pressure. For the broader picture, see Interview Versus Interrogation: What Is the Difference?

Where does cognitive load appear in Murder Book?

Murder Book: The Art of Interrogation is an upcoming narrative interrogation game from Gungrounds in Zagreb, Croatia, inspired by real police footage and psychological interviews. Development screenshots show an in-game casebook with an entry called Acting Emotion, which links failing to sustain a performed emotion to cognitive load theory.

That is a useful idea to explore in a story, and the research above suggests how to approach it. A character whose emotion slips might be performing, or might be exhausted, frightened or overwhelmed by the conversation itself. In Murder Book, a moment like that is a reason to look closer, not proof: it becomes meaningful only when it fits with what the character has said and what the evidence shows. The uncertainty is the point.

Murder Book is in development for PC (Steam) and mobile, with release currently planned for the end of Q2 2027.