GKT / CIT
Definition
Guilty Knowledge Test, also called Concealed Information Test (Lykken, 1959): tests whether the subject recognises crime-specific details only the perpetrator would know; preferred by researchers for its lower false-positive rate.
- Full name
- Guilty Knowledge Test / Concealed Information Test
- Originator
- David Lykken
- Year introduced
- 1959
- Key advantage
- Lower false-positive rate than the Control Question Test
Common questions
How does GKT/CIT differ from the standard polygraph CQT?+
The CQT compares physiological responses to relevant crime questions against control questions about general wrongdoing, while GKT/CIT presents multiple-choice items where only one option contains a true crime detail, and a larger response to that option indicates recognition rather than guilt.
Why do researchers prefer CIT over CQT?+
CIT's format allows statistical scoring against a known chance baseline, one correct option among several, giving it a much lower false-positive rate in laboratory studies, whereas CQT scoring relies on subjective comparison of responses across question types.
What limits the real-world use of CIT?+
It requires crime-scene details unknown to the public and not leaked to the suspect, which is hard to guarantee in cases with media coverage or careless interrogation, so many jurisdictions do not use it operationally at all.
Related terms
- BEOS
- Brain Electrical Oscillation Signature profiling, developed by Champadi Raman Mukundan and validated 2003 at NIMHANS Bangalore; uses 32-channel EEG to classify probes...
- CQT
- Control Question Test (Reid/Keeler technique): compares physiological response to relevant questions with response to control (probable-lie) questions; the dominant US polygraph format.
- Criminal Profiling
- The inference of an unknown offender's likely characteristics from crime scene behaviour, victimology, and case details. Also called offender profiling, criminal investigative...
- FBI BAU
- Behavioral Analysis Unit at the FBI Academy, Quantico, evolved from the Behavioral Science Unit set up by Howard Teten and Pat Mullany...
- Modus Operandi
- How the offender commits the crime: the functional behaviour needed to complete it; evolves with experience and feedback.
- Narco-Analysis
- A technique in which a subject is administered a barbiturate or benzodiazepine drug (commonly sodium pentothal or midazolam) to induce a hypnotic...
- Organised vs Disorganised
- The BSU dichotomy proposed by Ressler and Douglas, classifying offenders by scene presentation. Organised scenes show planning; disorganised scenes show chaos. The...
- P300
- Event-related brain potential occurring about 300 ms after a meaningful stimulus; Lawrence Farwell's 'Brain Fingerprinting' uses P300 amplitude to flag concealed recognition...
- Polygraph
- An instrument that simultaneously records multiple physiological channels including blood pressure, respiration rate, galvanic skin response, and sometimes heart rate while the...
- Signature
- Psychologically expressive behaviours that go beyond what's needed to complete the offence: posing the body, ritual acts, taking trophies, leaving messages. Signature...
- Sodium Pentothal
- Sodium thiopental, an ultra-short-acting barbiturate; intravenous infusion at a slow drip lowers cortical inhibition and is the standard agent for narco-analysis.