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One Minute First: We Use a Different Method

Why We Use EEG Rather Than a Polygraph

A polygraph does not measure lies directly. It records physiological arousal - heart rate, blood pressure, breathing and sweating - while you answer questions, and a trained examiner scores how those signals change between question types. The difficulty is that arousal has many innocent causes. Fear, embarrassment, medication and the simple dread of being wired to a machine can all produce it.

That is why the polygraph's best-documented risk is the false positive: an honest but anxious person scoring as deceptive. On accuracy, the practitioner body's own meta-analysis (American Polygraph Association, 2011) reports roughly 87-89% for validated single-issue techniques, while the most thorough independent review, the US National Academy of Sciences in 2003, found laboratory accuracy well above chance but well below perfection and the field evidence weaker. Both agree that question design and examiner skill matter a great deal.

P300 EEG: Testing Recognition, Not Stress

Instead of watching your body sweat, our test listens to your brain. EEG sensors record your brain's electrical activity while details connected to the events under investigation are presented alongside neutral items. When the brain recognises something it has genuinely encountered before, it produces a characteristic electrical response roughly 300 milliseconds after the stimulus appears. That response is the P300.

The critical difference is that the P300 is involuntary. It fires in about a third of a second, before conscious control is possible. You cannot breathe your way around it, you cannot rehearse it away, and staying calm makes no difference, because the test is not looking for stress in the first place. It is looking for recognition of the events in question.

Controlled laboratory studies of the P300 concealed information test typically report 80-95% correct classification, with limited field validation so far; those are published figures about the method, not results from our own testing. Countermeasures are not impossible: Rosenfeld and colleagues showed in 2004 that the original protocol could be defeated, which is why later protocols were designed to detect or resist them. What the method does change is the nerves problem: because nervousness does not by itself create a recognition response, an anxious but truthful person is not penalised for being anxious.

Side by side

Figures above are attributed to published research and describe the methods in general, not results from our own testing. For the sources, see our Polygraph vs P300 comparison and P300 explained pages.