Study reveals flaw in security checks

DURHAM, N.C., April 21 (UPI) -- U.S. researchers say a concept known as "satisfaction of search" might be preventing security workers from identifying dangerous contraband.

The scientists, led by Duke University Assistant Professor Stephen Mitroff, said missing items during a complex visual search is not a new idea. In the medical field, for example, it's been known since the 1960s that radiologists tend to miss a second abnormality on an X-ray if they've found one already.

"The concept -- dubbed 'satisfaction of search' -- is that radiologists would find the first target, think they were finished, and move on to the next patient's X-ray," the researchers said.

Mitoff and his colleagues said the same theory applies to non-medical areas, such as airport luggage screens.

In their study, Mitroff and his group asked college students to identify specific targets on a computer display. The frequency of easy- and hard-to-spot targets was varied. The scientists found when easy-to-find targets were more common, the subjects tended to overlook the hard-to-spot targets.

Mitroff said another possibility involved in the study might be an idea called "attentional set," which suggests finding one kind of target will make you more likely to find that same type of target, rather than a new, different one. In radiology, he said, it's like finding a fracture, which makes you more likely to find a second fracture rather than some other anomaly.

The study is detailed in the Journal of Experimental Psychology: Applied.