"That's an awful lot of people being pulled aside and inconvenienced," said Carnegie Mellon scientist Stephen Fienberg, who studied the TSA program and other counterterrorism efforts. "I think it's a sham. We have no evidence it works."...TSA's 'behavior detection' leads to few arrests
The TSA has not publicly said if it has caught a terrorist through the program. The agency says that some who are arrested, particularly on fake ID charges, may be scouting an airport for a possible attack.
Some scientists say the TSA effort is just as likely to flag a nervous traveler as a terrorist.
"The use of these technologies for the purpose that the TSA is interested in moves into an area where we don't have proven science," said Robert Levenson, a psychologist at the University of California-Berkeley.
Although observers can perceive whether someone appears anxious or is acting deceptively, they can't tell whether that person is planning an attack or something such as an extramarital affair, Levenson said.
Levenson and Fienberg were part of a National Academy of Sciences team whose report last month said "behavioral surveillance" has "enormous potential for violating" privacy.