"Transportation Security Administration officials aren't just concerned with what is in your luggage anymore. Some are being trained to assess what's going through your mind. Behavior Detection Officers who work for the TSA go through a week long training in order to look for travelers displaying involuntary physical and physiological reactions that indicate stress, fear or deception. Though the agency won't go into detail about what those indicators are, they say it's a sophisticated process to determine who needs additional screening."
KXAN has more details here.
This video is from KXAN Austin, broadcast July 29, 2008.