CHICAGO — A would-be terrorist tries to board a plane, bent on mass murder. As he walks through a security checkpoint, fidgeting and glancing around, a network of high-tech machines analyzes his body language and reads his mind.
Screeners pull him aside.
Tragedy is averted.
As far-fetched as that sounds, systems that aim to get inside an evildoer's head are among the proposals floated by security experts thinking beyond the X-ray machines and metal detectors used on millions of passengers and bags each year.
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On Thursday, in the wake of the Christmas Day bombing attempt over Detroit, President Obama called on Homeland Security and the Energy Department to develop better screening technology, warning: "In the never-ending race to protect our country, we have to stay one step ahead of a nimble adversary."
The ideas that have been offered by security experts for staying one step ahead include highly sophisticated sensors, more intensive interrogations of travelers by screeners trained in human behavior, and a lifting of the U.S. prohibition against profiling.
Some of the more unusual ideas are already being tested. Some aren't being given any serious consideration. Many raise troubling questions about civil liberties. All are costly.
Here's a look at some of the ideas that could shape the future of airline security:
The aim of one company that blends high technology and behavioral psychology is hinted at in its name, WeCU — as in "We See You."
The system that Israeli-based WeCU Technologies has devised and is testing in Israel projects images onto airport screens, such as symbols associated with a certain terrorist group or some other image only a would-be terrorist would recognize, company CEO Ehud Givon said.
The logic is that people can't help reacting, even if only subtly, to familiar images that suddenly appear in unfamiliar places. If you strolled through an airport and saw a picture of your mother, Givon explained, you couldn't help but respond.
The reaction could be a darting of the eyes, an increased heartbeat, a nervous twitch or faster breathing, he said.
The WeCU system would use humans to do some of the observing but would rely mostly on hidden cameras or sensors that can detect a slight rise in body temperature and heart rate.
If the sensors picked up a suspicious reaction, the traveler could be pulled out of line for further screening.
One system being studied by Homeland Security is called the Future Attribute Screening Technology, or FAST, and works like a souped-up polygraph.
It would subject people pulled aside for additional screening to a battery of tests, including scans of facial movements and pupil dilation, for signs of deception. Small platforms similar to the balancing boards used in the Nintendo Wii would help detect fidgeting.
At a public demonstration of the system in Boston last year, project manager Robert Burns explained that people who harbor ill will display involuntary physiological reactions that others — such as those who are stressed out for ordinary reasons, such as being late for a plane — don't.
The Israeli model
Some say the U.S. should take a page from Israel's book on security.
At Israeli airports, widely considered the most secure in the world, travelers are subjected to probing personal questions as screeners look them straight in the eye for signs of deception. Searches are meticulous, with screeners often scrutinizing every item in a bag, unfolding socks, squeezing toothpaste and flipping through books.
"All must look to Israel and learn from them. This is not a post-9/11 thing for them. They've been doing this since 1956," said Michael Goldberg, president of New York-based IDO Security Inc., which developed a device that can scan shoes for hidden weapons while they are still on people's feet.
While many experts agree the United States could adopt some Israeli methods, few believe the overall model would work here, in part because of the sheer number of large U.S. airports — around 400, versus half a dozen in Israel.
Also, the painstaking searches and interrogations would create delays that could bring U.S. air traffic to a standstill.
Some argue that policies against profiling undermine security.
Philip Baum, editor of the London-based magazine Aviation Security International, and also managing director of Green Light Limited, a London-based aviation security company, agrees profiling based on race and religion is counterproductive and should be avoided. But he argues that a reluctance to distinguish travelers on other grounds — such as their general appearance or their mannerisms — is not only foolhardy but dangerous.
"When you see a typical family — dressed like a family, acts like a family, interacts with each other like a family ... when their passport details match — then let's get them through," he said. "Stop wasting time that would be much better spent screening the people that we've got more concerns about."
Scrutinizing 80-year-old grandmothers or students because they might be carrying school scissors can defy common sense, Baum said.
"We need to use the human brain — which is the best technology of them all," he said.