Officer Ana Paz slowly scans the airport terminal, studying faces and luggage and movements, her right hand fixed on the semiautomatic rifle strapped to her chest. She has found her target.

The man looked angry, she thought. He probably was. He was waiting for his wife to get out of the restroom at Miami International Airport.

Authorities at about a dozen airports around the country are using “behavior pattern recognition,” or monitoring passengers’ involuntary actions in hopes of nabbing potential terrorists. The officers often zero in on people as harmless as the impatient husband, but security officials here are so impressed with the techniques that they plan to expand their use more widely than any other U.S. airport.

Logan International Airport in Boston has offered similar training to workers, including ticket agents and curbside attendants, but a spokeswoman said the program included only several hundred employees. If officials here have their way, all the airport’s 35,000 workers from janitors to skycaps to Starbucks baristas will be trained to watch travelers’ movements and detect potentially dangerous fliers.

“If you had 35,000 pairs of eyes observing suspicious behavior, that’s a strong layer of security,” said Greg Chin, a spokesman at Miami International Airport, where officials began training managers Thursday.

The Transportation Security Administration says officers at about a dozen airports are using behavior screening at checkpoints, though they wouldn’t say which ones, and they expect to expand the program further. In Miami, airport police — separate from TSA officers — are also using the methods.

Ann Davis, a TSA spokeswoman in Boston, where the agency launched its behavior screening effort, said the program has yielded about 95 arrests for fraudulent documents, money and drug smuggling, and other offenses, but it was not clear if any were specifically linked to terrorism.

“It has been successful in catching bad guys, but not bad terrorist guys,” said Richard Bloom, a dean who directs terrorism and security studies at Embry-Riddle Aeronautical University in Prescott, Ariz.

Such efforts are necessary because officers and technology are limited in what they can do, said Rafi Ron, the former security director at Ben-Gurion International Airport outside Tel Aviv, Israel. He now heads New Age Security Solutions, which is working with officials here.

Ron pointed to the example of would-be shoe bomber Richard Reid, who found lapses in security screening but whose behavior was ultimately noticed by fellow passengers.

He said most terrorists don’t have the “tremendous personal skills” needed to avoid being detected.

Those trained in behavior recognition are careful not to reveal what exactly would pique their interest. On a patrol with Paz it was clear it could be any number of things — someone rifling through a trash can, an unattended bag, a young man sitting on the floor alone, or a seemingly unhappy face.

“When you scan a crowd, you’re looking for what’s unusual,” said Paz, a 25-year veteran of the Miami-Dade Police Department assigned to the Incident Containment Team at the airport.

Such efforts have been in place at Ben-Gurion for years. They were brought to American airports after the Sept. 11 attacks, but Bloom says good security officers have long used behavior screening, though it was not an organized effort.

Not everyone is pleased, though.

The American Civil Liberties Union filed a lawsuit two years ago challenging the use of behavior recognition at Logan International Airport in Boston, claiming it “effectively condones and encourages” racial and ethnic profiling.

The ACLU sued after its national coordinator for racial profiling said state police harassed him at Logan last year.

“It’s the same as a public street — the authority of the police there is no different than it is in your office, in a public square,” said John Reinstein, legal director of the ACLU chapter in Massachusetts. “The police officer can approach you, can ask you questions, can ask you for identification, but under the circumstances you’re under no obligation to respond.”

In Miami, Ron told the roughly 70 training participants that behavior recognition was not about racial profiling and he deemed such screening ineffective. He noted the two terrorist attacks carried out at Ben-Gurion have been by individuals Israelis wouldn’t necessarily have expected — Japanese and Germans.

Something they do typically share, he said, is an uneasiness about what they’re about to do.

“If you’re carrying a device on you or in your bag, if you believe you’re going to heaven as these people do,” Ron said, “you behave differently.”