Hiding explosives in plain sight: Searchers thrown off by multiple targets
Researchers find that one strategy a terrorist might adopt is to carry explosives on his body - and liquid jell in his luggage; screeners would likely spot the jell, ask the passenger-terrorist to discard it - and, subconsciously influenced by “satisfaction of search,” move on to screen the next passenger; the research suggests that security might be improved if the screeners worked in a space where they could not see how many travelers were waiting in line and therefore did not feel pressure to hurry with the searches
Your statistics professor in college may have told you that the human mind can play tricks with what we think are straightforward choices on their merits. Take, for example, the lineup where a set number of options are presented one by one — say, five choices of a sandwich for lunch today. You have to make your final decision on Option 1 (the BLT) before you know anything about Option 2 and so on.
MinnPost’s Sharon Schmickle writes that here is where our minds start to play tricks on us: You really like BLTs, but still pass on Option 1 because something better might come along. If you get all of the way to Option 4 (peanut butter and jelly), you take it even though it is not your favorite — because your last chance, Option 5, might be chopped liver or something you find equally unappealing.
Researchers at Duke University studied a different mind game — one they suspected could compromise airport security. The concept they explored is known in medicine as “satisfaction of search.” If radiologist reading X-rays found one abnormality, they tended to miss a second one. They thought they were finished and moved on to the next patient’s X-ray.
The Duke team wondered whether satisfaction of search would also compromise airport security. In other words, is a security employee who finds an oversized bottle of shampoo in Traveler 1’s carryon luggage likely to move on to the next traveler and miss the box cutter that Traveler 1 also is carrying?
If so, the Transportation and Security Administration’s (TSA) restrictions on liquids and gels could backfire. Security screeners would find that kind of contraband relatively easily and then be more likely to miss banned items that were less readily apparent.
“The liquids rule has introduced a whole lot of easy-to-spot targets,” Duke professor Stephen Mitroff, who led the research, told e! Science News.
The answers to the basic question behind the research were complex. In the study, published online in the Journal of Experimental Psychology: Applied, Mitroff and his group found that several different factors influenced satisfaction of search. One factor was the frequency of the easy- and hard-to-spot targets.
College students in their studies had no trouble finding the hard-to-spot targets in the presence of an easy one. “But when the easy-to-spot item was two or three times more common, the subjects tended to overlook the hard-to-spot targets,” e! Science reported.
Schmickle notes that another factor was time. The students in the experiments were significantly more accurate when the time for a search was doubled, even though they didn’t use the full time extension.
“It didn’t seem to do with time itself, but it seems to be the time pressure,” Mitroff told e! Science News. “When you have the impending time pressure of going quickly, you are more likely to miss a second target.”
The research suggests that security might be improved if the screeners worked in a space where they could not see how many travelers were waiting in line and therefore did not feel pressure to hurry with the searches.
—Read more in Mathias S. Fleck, Ehsan Samei, Stephen R. Mitroff, “Generalized ‘Satisfaction of Search’: Adverse Influences on Dual-target Search Accuracy,” Journal of Experimental Psychology: Applied 16, no. 1 (March 2010): 60-71 (doi: 10.1037/a0018629)
