The Guilty Knowledge Test and the modified Stroop task in detection of deception: an exploratory study

Area of Science:

• Cognitive Psychology
• Forensic Psychology
• Neuroscience

Background:

• Deception detection is crucial in legal and security contexts.
• Psychophysiological methods like the Guilty Knowledge Test (GKT) are established lie detection techniques.
• The Stroop task, a measure of cognitive interference, has potential applications in deception detection.

Purpose of the Study:

• To investigate the efficacy of a modified Stroop paradigm in detecting deceptive behavior.
• To compare the performance of the Stroop task with the established Guilty Knowledge Test in identifying guilt and innocence.

Main Methods:

• A mock crime scenario was used with 40 university students.
• Participants completed a Guilty Knowledge Test (measuring skin conductance) and a modified Stroop task (color-naming crime-related words).
• The Stroop task was presented in a narrative format to assess differences in reaction times between relevant and irrelevant crime details.

Main Results:

• The Guilty Knowledge Test correctly identified 100% of innocent participants and 78% of guilty participants.
• Stroop interference, calculated as the difference in reaction times, did not significantly distinguish between guilty and innocent individuals.
• The narrative format of the Stroop task appeared to hinder its effectiveness in lie detection.

Conclusions:

• The Guilty Knowledge Test demonstrates high accuracy in differentiating between guilty and innocent individuals.
• The modified Stroop task, particularly in a story format, is not a suitable method for detecting deceptive behavior.
• Further research may be needed to explore alternative Stroop task formats for potential lie detection applications.