Looking nervous? Yawning too much? TSA may be keeping an eye on you.

At airports around the country, Transportation Security Administration (TSA) agents are screening passengers and their stuff.

Looking through luggage this past week, they came upon the typical illegal arsenal: 53 firearms (44 of which were loaded and 24 with rounds chambered), filled ammunition clips, a live smoke grenade, stun guns, and a variety of large knives, one of them concealed inside a belt buckle. TSA doesn’t regularly report such encounters, but the week also likely included a number of passengers pulled aside for questioning and perhaps extra physical checking.

Now, the reasons for that extra questioning have been revealed by The Intercept, the online publication that first went public with the documents provided by ex-NSA contractor Edward Snowden.

As they scan passengers, TSA “behavioral detection officers” look for “stress factors,” “fear factors,” and “deception factors.”

“The checklist ranges from the mind-numbingly obvious, like ‘appears to be in disguise’ … to the downright dubious, like a bobbing Adam’s apple,” The Intercept reports. “Many indicators, like ‘trembling’ and ‘arriving late for flight,’ appear to confirm allegations that the program picks out signs and emotions that are common to many people who fly.”

The 92-point checklist includes body odor, exaggerated yawning, excessive throat clearing, widely open staring eyes, exaggerated or excessive grooming gestures, a face pale from the recent shaving of one’s beard, rubbing or wringing of hands, and an “obvious ‘Adam’s Apple’ jump” when asked to go through screening procedures.”
 

The American Civil Liberties Union (ACLU) has sued TSA under the Freedom of Information Act (FOIA) for documents related to the SPOT program.

“The TSA's use of such techniques raises serious civil liberties concerns about racial and religious profiling and has been criticized as ineffective and lacking a valid scientific basis,” the ACLU says in its FOIA request.

“The Government Accountability Office and independent scientific advisory groups have concluded that there's just no evidence that humans can reliably detect deception or ill intent in others based on their behavior,” ACLU attorney Hugh Handeyside told NPR. “The program has led to numerous allegations of racial and religious profiling, which isn't surprising given that you're basically giving TSA officers permission to make hasty, gut-level judgments about people's intentions based on nothing more than their facial expressions or their behavior.”

University of Chicago behavioral scientist Nicholas Epley is skeptical as well.

“The data that comes from experiments that test whether people can detect these subtle kinds of cues suggest that it can't be detected very well,” Dr. Epley said on NPR. “There are certainly lots of claims about how body language can be read better if you're trained, but a lot of those kinds of claims come without data to back them up.”

For its part, TSA is standing by its SPOT program as a necessary part of airport and air travel security.

“Behavior detection, which is just one element of the Transportation Security Administration’s (TSA) efforts to mitigate threats against the traveling public, is vital to TSA’s layered approach to deter, detect and disrupt individuals who pose a threat to aviation,” an agency spokesman said in a statement to The Intercept. “No single behavior alone will cause a traveler to be referred to additional screening or will result in a call to a law enforcement officer.”