Not long after the 9/11 hijackings, airports across North America instituted a “behavior-detection” program, where trained observers watch passengers at security checkpoints, looking for nervous or suspicious behavior. Well, the TSA recently began testing an expanded program at Boston’s Logan International Airport, where the officers actually talk to the passengers instead of just passively watching them.

Officials say it’s basically a casual “Hi, how are you?” type of conversation, when you hand over your ID and boarding pass. They’re looking for body language or facial expressions that reveal tension, fear, or deception. And passengers that raise red flags are screened more closely, and may be asked to speak to law enforcement.

These new security practices have been compared to security measures used in Israel, where security officers aggressively question every passenger before they’re cleared for boarding. As a result, they have one of the most secure airports in the world.

But critics of the new program say that asking questions is too intrusive, and amounts to profiling.  And that passengers shouldn’t be prevented from flying because some officer has a “hunch” that they might be up to no good.

But the TSA insists it’s sound behavioral science and that the program has already resulted in more than 2-thousand arrests of suspicious travelers.