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Accurate lie detection could be scientifically impossible

On Behalf of | Jan 17, 2024 | Criminal Defense

Police officers in Mississippi and around the country have long yearned for a reliable way to tell whether or not a suspect is lying. Polygraph machines, which are often called lie detectors, have been in use for almost a century, but the results they produce are not accurate or reliable enough to be used as evidence in a criminal trial. Approaches that identify false accounts by analyzing statements or memories are about as accurate as polygraph machines, and using artificial intelligence algorithms to separate truth from lies has also failed to produce results that are reliable enough to be used in court.

Polygraph machines

Many people think of polygraph machines as modern technology, but they have been in use since the late 1920s. These machines identify lies by measuring nonverbal behavior like breathing, heart rate and perspiration, but they are only accurate about 70% of the time. If evidence this unreliable was used in court, a criminal defense attorney would have an opportunity to establish reasonable doubt. In 2003, a report released by the National Academy of Sciences concluded that polygraph machines have little scientific merit.

Reality monitoring, MRI machines and AI

Criterion-based content analysis and reality monitoring are two approaches for finding the truth that have been embraced by academia in recent years. CBCA and RM analyze statements or explore memories to identify falsehoods, but their accuracy rates are no higher than 70%. Advanced algorithms can identify patterns and subtle nuances more accurately than human beings, but a study published in 2021 reveals that they only identify false statements about 69% of the time. Some experts believe that MRI machines could become accurate lie detectors, but there is evidence to suggest that habitual liars and occasional liars have different neurology.

The human brain

The human brain is the most complex thing in the observable universe, and scientists have yet to unlock its mysteries. Polygraph machines have been in use for almost 100 years, but the results they provide are not accurate enough to be used in court. Alternative methods for identifying lies have been suggested and tested, but none of them have proved to be more accurate than polygraph machines.