According to new research at Duke University, identifying an easy-to-spot prohibited item such as a water bottle may hinder the discovery of other, harder-to-spot items in the same scan.
Missing items in a complex visual search is not a new idea: in the medical field, it has 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.
Does the principle apply to non-medical areas? That's what Stephen Mitroff, an assistant professor of psychology & neuroscience at Duke, and his colleagues set out to examine shortly after 2006, when the U.S. Transportation Security Administration banned liquids and gels from all flights, drastically changing airport luggage screens.
"The liquids rule has introduced a whole lot of easy-to-spot targets," Mitroff said.
In the new study, published online in the Journal of Experimental Psychology: Applied, Mitroff and his group asked college students to identify specific targets on a computer display – in this case, two perpendicular lines that form the letter "T" amid distracters, such as Ls and non-Ts. In some cases, Ts were easy to spot, and in other cases more difficult because they blended in with the background.
In an initial set of experiments, Mitroff and his colleagues altered the frequency of easy- and hard-to-spot targets. When the two kinds of targets appeared with equal frequency, subjects apparently had no trouble finding the hard-to-spot target 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.
When Mitroff's group doubled the time allowed for each search, they saw that the students used barely a second of extra time but were significantly more accurate.
"It didn't seem to do with time itself, but it seems to be the time pressure," Mitroff said. "When you have the impending time pressure of going quickly, you are more likely to miss a second target."
Intriguingly, the data do not suggest subjects miss the second targets because they are too quick to end their search, an idea that would have bolstered the original satisfaction-of-search principle. "There seems to be some other mechanism, but it's not exactly clear what it is," Mitroff said.
One possible explanation is an idea called "attentional set," which suggests that 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, it is like finding a fracture, which makes you more likely to find a second fracture rather than some other anomaly.
In an additional set of experiments, the researchers added time and accuracy pressure to the test by introducing small baggage icons that appeared along the top of the screen, mimicking a new bag on the security conveyer belt. One bag disappeared when subjects finished searching each display. They earned points for each display and the more quickly and accurately the subjects could identify the targets, the higher the points they received.
For one group of subjects, researchers set the speed of bags based on the each person's performance in a previous practice session. That group wasn't any worse at finding the second target than the first. In contrast, subjects following a brisk rate set by the researchers were worse at finding the second target.
"The results fit with what we think would happen if you remove the searcher from seeing the line," Mitroff said. In a remote search, the screeners will not know whether there is one person or 500 people waiting. "It's not in use, but these data suggest that it might be something worth trying."
Mitroff's group next has plans to replace T-targets with multiple targets of different types, such as tools and bottles.
Citation: Generalized "satisfaction of search": Adverse influences on dual-target search accuracy. Fleck, Mathias S.; Samei, Ehsan; Mitroff, Stephen R. Journal of Experimental Psychology: Applied. Vol 16(1), Mar 2010, 60-71. doi: 10.1037/a0018629
Karl Leif Bates | EurekAlert!
Smart Data Transformation – Surfing the Big Wave
02.12.2016 | Fraunhofer-Institut für Angewandte Informationstechnik FIT
Climate change could outpace EPA Lake Champlain protections
18.11.2016 | University of Vermont
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
07.12.2016 | Health and Medicine
07.12.2016 | Life Sciences
07.12.2016 | Health and Medicine