Many Americans made security their top priority after Sept. 11, buying up gas masks, avoiding bridges and tunnels and staying alert to the possibility of another terrorist strike.

But can those same people maintain that heightened state of vigilance in light of the U.S. government's repeated — and as yet unrealized — warnings of subsequent attacks?

"People get better at handling these things," said Frank Farley, former president of the American Psychological Association. "It's almost entering the realm of the routine."

Still, Farley warned, "You can't stay on totally high alert forever. People just can't take it. The level of stress and the level of focus is so high that there will be consequences — physical and psychological."

Experts say the consequences can include difficulty concentrating, errors on the job, sickness, alcoholism, irritability and problems at home.

And even if those warnings are taken seriously, what can really be done about them? Not much, say some.

"By the time 'a possible threat' is announced, its moment in the limelight has already passed," said Kristina Malcolm, project manager for Fairmont Hotels & Resorts in San Francisco, Calif. "The only true threats are the totally unexpected ones … the ones we can't prepare for," she said in a recent interview.

"To be advised to go about your usual activities but with a heightened awareness doesn't really give you much to go on. That's like saying, 'Be aware of hungry lions while in the jungle' … I mean, that bad boy gets a whiff of you and the game's over. What good does being aware do you?"

The latest official warning came on Dec. 3, when Homeland Security Director Tom Ridge announced the third in a series of terror alerts.

"We do know that the next several weeks, which bring the final weeks of Ramadan and important religious observations in other faiths, have been times when terrorists have planned attacks in the past," Ridge said at a widely publicized White House press conference.

Attorney General John Ashcroft issued similar warnings on Oct. 11 and Oct. 29, respectively. Those warnings were also widely publicized, though they sparked a few complaints from state and local officials who said the information wasn't particularly useful.

"There's not a lot more — minus a specific threat against a specific target — that we can put in place," said Denver's safety manager, Ari Zavaras.

Some civilians said the warnings were both necessary and appreciated.

"I don't get tired of these warnings. I get tired of the threat," said Hugh Bouchard, a publishing specialist in Boston. "But I feel we've got good people defending our country in all sorts of ways and that we can deal with whatever problems come our way.

"I think we were caught completely off guard by the 9/11 attacks, which made us all a little paranoid, and rightly so," Bouchard added. "Three months on, I think we've had a lot of good developments … people realize this and feel a lot safer."

Others, however, seemed blissfully unaware of the latest alerts.

"I've let my guard down somewhat," said Bruce Chen, a Minneapolis computer technician. "But, I mean, isn't the Taliban about gone? Haven't they about got rid of them over there?"

That experience is somewhat more muted in New York City, the epicenter of terror's wrath.

"Even though most people, including myself, have seemingly gone back into our normal routine ... I think there is still a tension level, a keener sense of your surroundings and potential dangerous situations," said Caroline Fennessy Campion, a magazine editor.

While Campion said she trusts the government alerts, she thinks the panic stage has died down.

"Gas mask chic, buying gloves to open the mail … they were all typical of our mentality to jump on the bandwagon, and now it all looks a bit ridiculous. Everyone handles panic situations in different ways though, and I'm sure if something else, something tangible were to happen, many people would swing back into panic mode."

The Associated Press contributed to this report.