Authorities said they were amazed that someone would wear such a device eight months after a similar scare in Boston, and six years after two of the jets hijacked in the Sept. 11 attacks took off from Logan.

"I'm shocked and appalled that somebody would wear this type of device to an airport," said State Police Maj. Scott Pare, the airport's commanding officer.

Simpson showed "a total disregard to understand the context of the situation she is in, which is an airport of post-9/11," prosecutor Wayne Margolis said at a hearing where a not guilty plea was entered for Simpson and she was released on $750 bail. Margolis had asked for $5,000 bail.

Simpson, of Lahaina, Hawaii, was arrested Friday morning outside Terminal C, home to United Airlines, Jet Blue and other carriers.

She wore the white circuit board on her chest over a black hooded sweat shirt, Pare said at a news conference. The battery-powered rectangular device had nine flashing lights, and Simpson had Play-Doh in her hands, he said.

Two phrases that looked hand-drawn — "Socket to me" and "Course VI" — were written on the back of Simpson's sweat shirt, which authorities displayed to the media. Course VI appears to refer to Massachusetts Institute of Technology's major of electrical engineering and computer science.

"She said that it was a piece of art and she wanted to stand out on career day," Pare said. "She claims that it was just art, and that she was proud of the art and she wanted to display it."

There was a career fair at the university on Thursday, according to the university's Web site.

Simpson is the secretary of MIT's Electrical Research Society, according to her lawyer. She is a graduate of the Hawaii Preparatory Academy, a private boarding school, has won school prizes for chemistry and leadership and had received a Congressional citation for her work in robotics, said Ross Schreiber, who was appointed to represent Simpson.

He said she was not a risk to flee, cooperated with authorities and was a good student with no prior convictions. He said they would fight the charges.

"I would characterize it as almost being paranoid at this point," Schreiber said of authorities' response.

He said Simpson had gone to the airport to meet her boyfriend. "She was there for legitimate purposes," Schreiber said.

A Massachusetts Port Authority staffer manning an information booth in the terminal became suspicious when Simpson — wearing the device — approached to ask about an incoming flight, Pare said. Simpson then walked outside, and the staffer notified a nearby trooper.

The trooper, joined by others with submachine guns, confronted her in front of the terminal.

"She was immediately told to stop, to raise her hands and not to make any movement, so we could observe all her movements to see if she was trying to trip any type of device," Pare said. "Had she not followed the protocol, we might have used deadly force."

He added, "She's lucky to be in a cell as opposed to the morgue."

The terminal was not evacuated and flights were not affected, airport officials said.

Boston was the focus of a security scare Jan. 31 when dozens of battery-powered devices that featured a character making an obscene gesture with a finger were discovered in various locations. Bomb squads were deployed and some transportation links were closed temporarily. They turned out to be a promotion for the Cartoon Network. Two men were charged in that incident, but prosecutors dropped the charges after they apologized and performed community service.