The Lying Study

I've seen news reports about a new study that shows different areas of the brain are used when lying than when telling the truth, and that those differences show up on an MRI. Might be big stuff in the area of lie detector tests. But when I read the story, I noted that the study could be tainted. Jim Lindgren beat me to the punch, explaining why in this post on the Volokh Conspiracy:

Faro and colleagues tested 10 volunteers. Six of them were asked to shoot a toy gun and then lie and say they didn't do it. Three others who watched told the truth about what happened. One volunteer dropped out of the study.



While giving their "testimony," the volunteers were hooked up both to a conventional polygraph and also had their brain activity imaged using fMRI, which used a strong magnet to provide a real-time picture of brain activity.



There were clear differences between the liars and the truth-tellers, Faro's team told a meeting in Chicago of the Radiological Society of North America.



. . . .



How can they tell? There is no basis in the news report to think that the experiment tested lying v. truth-telling as opposed to gun shooting v. passively watching. The two experiments are completely confounded.

Exactly. The point is only to change one variable, so you can isolate what is causing the difference in the brain waves. They should have had half the shooters lie and half tell the truth. Then they should have done a separate trial with all watchers, then have half of them lie and half tell the truth. That way you can see: 1) Is there a brain wave difference between lying and truth telling; and 2) Is there a difference when it's lying about an activity vs. a passive/witness role. This way they're all messed in together with no way to tell what caused the difference. I'm surprised the study got approval, I know this and I've only taken elementary-level psych stuff in undergrad.