Sheffield Lie Test (SLT)

Background

The Sheffield Lie Test (SLT) is a standardized cognitive-behavioral task to study the cognitive mechanisms and response times associated with deception. Sean Spence and colleagues from the University of Sheffield designed the task in 2001 as an objective, behavioral measure of lying while studying brain activation during deception. Shortly before the actual study, participants were asked to provide(truthful) answers to 36 yes/no questions such as "Have you made your bed today?". During the test, these 36 questions were asked again twice: Once under a "LIE" condition, and once under a "TRUTH" condition. Sheffield et al found that lying was associated with longer response times (likely because lying requires inhibition of truthful responses) and greater activity in bilateral ventrolateral prefrontal cortices.

The Millisecond SLT is based on the original Inquisit script used by Ralph Bagnall and colleagues in their 2024 study on everyday-lying in individuals on the autism spectrum. They found that individuals on the autism spectrum were not less inclined to lie compared to a control group. However, the authors report that the factors underpinning the inclination to lie (or not to lie) differed between groups: Lower self-rated lying ability and slower lie speed predicted a reduced inclination to lie in autistic participants, whereas higher theory of mind (ToM) and working memory capacity predicted a reduced inclination to lie in the non-autistic group.

Task Procedure

The Millisecond SLT runs three phases: two practice phases and one test phase. During the practice phases, statements are used with generally agreed correct/incorrect answers (e.g. 'Do bicycles have two wheels?'). Practice phase 1 runs 8 trials in a fixed sequence, alternating Truth and Lie condition for the same four statements. Feedback is provided after each statement. Practice phase 2 runs an additional 8 trials where 4 statements are tested in a randomized order. No further feedback is provided. The test session runs 40 questions about everyday activities with anticipated correct/incorrect answers (e.g. "Have you washed your hands during the last 24 hours?"). Half the questions are anticipated to have a 'yes' answer as the truth, half the questions are anticipated to have a 'no' answers as the truth. The 40 questions are tested twice, once under the TRUTH condition and once under the LIE condition. The order of the resulting 80 questions is randomized.

What it Measures

The Sheffield Lie Test (SLT) primarily measures cognitive effort required in deception

Psychological domains

• Inhibitory Control: The cognitive effort required to actively stop oneself from stating the automatic truth
• Cognitive Flexibility: The ability to shift between different rules (truth-telling vs. lying) based on a visual cue
• Working Memory: The processing capacity used to hold the true answer in mind while formulating and executing a false one.
• Theory-of-Mind (ToM): The ability to understand internal mental states of other people

Main Performance Metrics

• Response Time Differences: the mean response time difference in telling the truth vs. lie; a positive difference is indication of deception effort

Psychiatric Conditions

The Sheffield Lie Test (SLT) has been used in research with the following clinical populations

• Autism Spectrum Disorder (ASD)
• Schizophrenia

References

Search Google Scholar for peer-reviewed, published research using the Inquisit Sheffield Lie Test (SLT).

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Spence, S. A., Farrow, T. F., Herford, A. E., Wilkinson, I. D., Zheng, Y., & Woodruff, P. W. (2001). Behavioural and functional anatomical correlates of deception in humans. Neuroreport, 12(13), 2849-2853.

Debey, E., Verschuere, B., & Crombez, G. (2012). Lying and executive control: An experimental investigation using ego depletion and goal neglect. Acta Psychologica, 140(2), 133–141. https://doi.org/10.1016/j.actpsy.2012.03.004

Debey, E., Ridderinkhof, R. K., De Houwer, J., De Schryver, M., & Verschuere, B. (2015). Suppressing the truth as a mechanism of deception: Delta plots reveal the role of response inhibition in lying. Consciousness and Cognition, 37, 148–159. https://doi.org/10.1016/j.concog.2015.09.005

Verschuere, B., & In T Hout, W. (2016). Psychopathic Traits and Their Relationship with the Cognitive Costs and Compulsive Nature of Lying in Offenders. PloS One, 11(7), e0158595–e0158595. https://doi.org/10.1371/journal.pone.0158595

Bagnall, R., Russell, A., Brosnan, M., & Maras, K. (2024). Autistic adults’ inclination to lie in everyday situations. Autism : The International Journal of Research and Practice, 28(3), 718–731. https://doi.org/10.1177/13623613231183911