For the next two months at Logan International Airport in Boston, passengers will be casually greeted by Transportation Security Administration officials. But the officers aren't there for a friendly "hello" — they're trying to deter and detect passengers who pose a risk to aviation security.

As part of the TSA's new behavior-detection pilot program that started this week, screeners are engaging each passenger in Terminal A in casual conversation in an effort to detect suspicious behavior. After passengers provide their boarding pass and ID, they have to answer a few questions from TSA officers who have received two weeks of training.

"It's one layer of security that will allow us to provide additional screening and concentrate on passengers who may pose a higher risk," TSA spokesman Greg Soule said.

The program is an evolution of the TSA's Screening of Passengers by Observation Techniques, or SPOT, Program, which started at Logan in 2003 and has expanded to 160 airports. It has helped arrest 2,000 criminals, but none has been charged with terrorism.

Under the SPOT program, TSA screeners interrogate individuals only after they have been identified as suspicious. Now, at least at Logan, everyone is a target. After 60 days, the TSA will decide whether to expand the program to other airports.

Paul Ekman, professor emeritus at UC San Francisco, who helped develop the SPOT program, said his research indicated that talking to passengers "loosens things up," increasing the chances that they will show signs that they're concealing something. The subject matter of the discussion is irrelevant; all that matters is that the passenger is speaking.

"If all you're doing is watching people standing in line, that's better than doing nothing, and they've had quite a bit of success," Ekman said. "But I would expect that by asking a few fairly innocent questions — 'What's the purpose of your trip?' — that will increase accuracy."

Ekman said that when typical federal employees were asked to detect deception, they failed miserably. That all changes with "an hour's training," he said. Ekman added that the TSA would continue to use a tool developed for the SPOT program that allowed officials to identify "micro-expressions" — facial expressions that occur in 1/25 of a second that are designed to conceal emotion.

Others are skeptical that a run-of-the-mill TSA official can develop the detection techniques necessary to spot suspicious behavior.

Glenn Reynolds, a law professor at the University of Tennessee and an outspoken critic of the TSA, said that although some people were capable of detecting deception, it was much more difficult to teach the art.

"If you're a TSA screener, if you ever meet a terrorist at all, it will be the only one you meet in your whole career," Reynolds said, noting that terrorists are difficult to identify to the untrained eye. In contrast, "if you're a cop on the beach, you deal with drug dealers all the time," making it easier to identify a drug dealer.

Soule said the TSA was working with experts in the field who used behavior detection as part of their job.

It remains unclear whether a short conversation can produce any meaningful information. At Ben Gurion International Airport near Tel Aviv in Israel, every passenger is questioned at length before boarding a plane. The difference, Ekman noted, is that 50,000 people board planes in Israel each day, compared with 2 million in the U.S.

"Asking a few questions is better than asking none," Ekman said. "If you could ask many questions, it might be better than a few, but we don't really know that."

andrew.seidman@latimes.com