CHICAGO – Functional magnetic resonance imaging can identify activation in specific regions of the brain when people lie and one day could be used to augment or replace polygraph testing, Scott H. Faro, M.D., said at the annual meeting of the Radiological Society of North America.
“We have just begun to understand the potential of fMRI [functional magnetic resonance imaging] in studying deceptive behavior,” said Dr. Faro, professor and vice chair of radiology and director of the functional brain imaging center and clinical MRI at Temple University, Philadelphia.
“We plan to investigate the potential of fMRI both as a standalone test and as a supplement to polygraph, with the goal of creating the most accurate test for deception,” he said.
His research involved the examination of 11 volunteers with simultaneous fMRI and polygraph testing. Six of the subjects had been asked to shoot a toy gun and then lie about their participation, whereas the nonshooters were asked to tell the truth. In addition to being asked about the shooting, all subjects were asked unrelated control questions.
In all cases, fMRI and polygraph accurately identified the deceptive responses.
The fMRI showed activation in different areas of the brain, depending on whether a subject was being deceptive or truthful. The use of a real-life stimulus was a very important part of this study because this scenario can elicit strong activation of emotional and cognitive centers in the brain, which can be seen with fMRI, Dr. Faro said.
The investigators found that, during deception, activation was seen in the left medial, left inferior, and right precentral regions of the frontal lobe; the right hippocampus and right middle regions of the temporal lobe; and the anterior and posterior cingulate regions of the limbic lobe.
During truthful responses, activated areas included the left inferior and right medial regions of the frontal lobe, the left inferior region of the temporal lobe, and the posterior cingulate gyrus in the limbic lobe.
Some areas of the brain were activated during both lying and truth-telling, but there were five activated areas unique to lying: two in the frontal lobe (the right precentral gyrus and the left medial frontal gyrus), two in the temporal lobe (the right hippocampus and the right middle temporal lobe), and the anterior cingulate of the limbic lobe.
Investigation into other means of lie detection is important because polygraph testing is considered only 90% accurate, he said.
The polygraph test only measures peripheral physiologic responses, including galvanic skin conductance, which increases during perspiration, blood pressure, and respiration. These physiologic responses can vary among individuals, however, and can be self-regulated. “The deception response begins in the brain and controls all aspects of behavior. That is why the brain is the focus of our research,” Dr. Faro said.
It is too early to tell whether fMRI results can be self-regulated, but the results suggest that the consistencies in brain activation patterns seen on fMRI may be beyond conscious control.
Dr. Faro's research is the first to use polygraph correlation and a modified version of control questioning techniques with fMRI. In addition, his research is the first to use a real-life stimulus, which is critical if the technique is to be developed into a practical test, he said.
These fMRI images show areas found to be active in the group analysis data of the subjects when they were asked to be deceptive. The cross hair in each image represents the hippocampus, one of the areas showing activity. Courtesy Feroze B. Mohamed, Ph. D.