P300
Definition
Event-related brain potential occurring about 300 ms after a meaningful stimulus; Lawrence Farwell's 'Brain Fingerprinting' uses P300 amplitude to flag concealed recognition of crime details.
- Type
- Event-related brain potential
- Latency
- About 300 ms after a meaningful stimulus
- Application
- Lawrence Farwell's 'Brain Fingerprinting'
- Purpose
- Flags concealed recognition of crime details
Common questions
Is P300-based 'Brain Fingerprinting' widely accepted as courtroom evidence?+
No, its forensic use remains contested. Courts in most jurisdictions have been cautious or have excluded it, citing concerns about scientific validation, countermeasures, and the difference between recognition and guilt, unlike more established EEG or neuroimaging applications.
What does a P300 response actually indicate about a suspect?+
It indicates the brain recognised a stimulus as familiar or meaningful, not that the person committed a crime, so a P300 response to crime-scene details shows only that the person has prior exposure to that information, which could arise innocently.
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...
- GKT / CIT
- Guilty Knowledge Test, also called Concealed Information Test (Lykken, 1959): tests whether the subject recognises crime-specific details only the perpetrator would know;...
- 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...
- 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.