NPR series on lie detection

NPR has just finished an interesting series on lie detection. You can listen to it at

http://www.npr.org/templates/story/story.php?storyId=15670581

This series is all about accuracy, and it makes it clear that lie detection is not very good, and will never be perfectly accurate. That means it will always be necessary to set a threshold, and the threshold, of course, will depend on the costs and benefits of various outcomes. I am not surprised that a series like this says nothing about thresholds. But the people who develop and use these methods should certainly be concerned about thresholds.

It is also interesting that there is a reference to mental "systems" in the second segment of the report, which is about the use of fMRI to determine whether people are telling the truth. Although it is not stated explicitly, we can infer that they are assuming that lying requires analytic cognition, and therefore activates "system 2," which can be detected using fMRI.