Study reveals how to trick nearly unbeatable brain lie detectors

A new study has revealed two relatively simple methods that can be used to trick a brain imaging lie detector, which utilizes a functional MRI (fMRI) machine instead of a traditional polygraph system. Unlike techniques used to evade normal lie detection methods, researchers found that someone undergoing a brain imaging lie detection test can drastically reduce the results accuracy with two thought techniques.

Compared to polygraphs, brain imaging is considered a more reliable way to determine whether someone is lying because it works by monitoring the blood flow in the participant's brain. The idea is that if the person concentrates on concealing their recognition of whatever it is they're lying about, the fMRI will reveal greater amounts of blood in brain regions that work extra hard on hiding the info.

Researchers with the University of Plymouth identified two countermeasures that reduced the accuracy of brain imaging lie detector results by 20-percent. The first method involved the participant associating 'meaningful memories' with the control item, which was an item other than the one the participant was attempting to conceal.

The brain of someone who, for example, stole a particular item and is shown multiple items that include the stolen object, may give away the person's knowledge of the stolen item when they view it. Associating something meaningful with one of the other objects may increase their response to them, helping mask the changes that happen when they view the target object.

In addition, the researchers revealed that the subjects can reduce results accuracy by focusing on a superficial aspect of the target object, such as its color or shape, to reduce their brain's response to the item. The fMRI system struggled to find differences in brain activity when these methods were used, causing accuracy to drop by around 20-percent.