Lie detection

Lie detection is the practice of determining whether someone is practicing deception. Activities of the body not easily controlled by the conscious mind are compared under different circumstances. Usually this involves asking the subject control questions where the answers are known to the examiner and comparing them to questions where the answers are not known.

Lie detection commonly involves the polygraph but voice stress analysis may be more common because it can be applied covertly and to voice recordings.

The Polygraph detects changes in body functions not easily controlled by the conscious mind such as skin conductivity.

An FMRI can be used to compare brain activity differences.

Electroencephalography is used to detect changes in brain waves.

Another system measures the reflection of infared light shown through the forehead of a subject.

Brain fingerprinting uses electroencephalography to determine if an image is familiar to the subject. This could detect deception indirectly but is not a technique for lie detecting.