top of page

You’ll Never Believe This… Or Will You?

If you know anything about concealed information tests (CIT)–and in particular that the psychophysiological technique is scientifically valid in exposing people with crime-related knowledge–you might think twice before planning your next heist. But you can, in fact, avoid exposure when taking the test.

Let’s start by discussing how the test works. Functional magnetic resonance imaging (fMRI) analyzes changes in brain activity linked to cognitive processes involved in lying. The test is used to track changes that occur in blood oxygenation and flow in response to neural activity, but fMRIs do not directly measure neural activity. Studies show that, “Instead, [fMRI] measures small and variable changes in the ratio of oxygenated to deoxygenated blood in the brain when a particular task is performed or stimulus presented—the so-called BOLD, or blood oxygen level-dependent, response.” In testing the accuracy of fMRIs in lie detection, many scientists have instructed their subjects on how and when to lie. These direct instructions blur the validity of the results, begging the question: “does this really constitute lying?” Another complication is that repeated lies, and those first told long ago, appear differently on fMRI from an “unpracticed or recent lie.”

After taking these problems into account, scientists thought one step further and realized that subjects could use countermeasures to produce inaccurate or misleading results. These countermeasures include moving during the test and ignoring instructions. In a study conducted by Giorgio Ganis and his colleagues, participants were told to slightly move their hands or feet prior to pressing a response button. The results of this study show that, with the countermeasure in play, fMRI accuracy plummeted to a mere 33 percent. Another study executed by Melina Uncapher and her colleagues revealed that participants were able to successfully cloak their memory, manipulating “hippocampal activity—a region long known to be important for memory—and distributed neural patterns.” In general, this and other research has proven that fMRIs biased by countermeasures are 20% less accurate than those that aren’t.

What this means for you: before you rob a bank or swipe an old lady’s purse, commit the lessons of this blog post to heart to improve your chances of getting away it with it. Or, better yet, just don’t do it.


- Irene Tussy, Writer


Sources: Science Daily and Columbia Law School Scholarship Archive



bottom of page