Baggage security screening – slow is good?

Baggage security screening – slow is good?

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10747428_sThe next time that you are moving at a snail’s pace through airport security, calm yourself with the assurance that a slower and more deliberate baggage scanner may be doing a better job.

In a laboratory test of visual searching ability, scientists found trained Transportation Security Administration (TSA) screening officers were a lot slower than undergraduate students and other civilians but the amateurs were sloppier.

A Duke University release reports that the test is part of ongoing research by Duke University psychologist Stephen Mitroff to understand how the brain manages visual searching, important not only to security but also to cancer screening. Adam Biggs, a postdoctoral associate in Duke’s Center for Cognitive Neuroscience, ran this series of tests on 206 TSA professionals based at Raleigh-Durham Airport (RDU) and 93 Duke undergraduates.

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Participants performed an artificial search test on a computer screen on which they had to identify one particular T-shaped arrangement of two rectangles in a field of eight to 32 similar shapes. Half of the screens they looked at didn’t include the correct shape.

Though not as complex nor difficult as looking at real bags, the artificial test put the students and professional searchers on equal footing. “If we just showed undergrads real baggage images, they wouldn’t know what to look for,” Biggs said.

The researchers measured searchers’ speed and accuracy over 256 tests per participant. They also split the TSA screeners in to two groups to distinguish those with less than three-year experience and those with more than six-year experience, but they did not find any significant differences between them in basic screening abilities. Both TSA groups, who have been trained on how to search, outperformed the undergrads.

The students were 82 percent accurate at finding the target shapes, but on average only took 3.86 seconds per scan. The TSA searchers took longer — more than 6 seconds on average — but had accuracy rates of 87 and 88 percent.

The students also showed more variability in response time as the set of objects got larger; the professionals were more consistent.

Biggs said the professional screeners who took the test may be slower on the artificial task because their training makes them take more into consideration. Eye-tracking wasn’t used in these experiments, but measures of their speed and consistency indicate it’s likely the trained searchers were more systematic and methodical.

Earlier research by Mitroff’s group and others has shown that memory plays an important role in searching. A slower, more consistent pattern of searching frees up some of the brain’s processing, because the searcher doesn’t have to remember what has already been examined.