Smartphone games teach scientists how to save lives

These days, the ubiquity of smartphones makes it easy to call up a quick game of Angry Birds or Candy Crush and spend a few fun but ultimately unproductive minutes swiping around the screen. Duke psychology professor Steve Mitroff has discovered that the massive amounts of data generated by millions of people ostensibly wasting time can actually help save lives and protect national security.

One night, while waiting for his one-year-old daughter to fall asleep, Dr. Mitroff found a smartphone game called Airport Scanner, in which players man airport x-ray scanners and search for illegal objects amongst cluttered cartoon suitcases. The game dynamics paralleled Dr. Mitroff’s research on how we find specific visual targets amid complex visual scenes. This caused him to wonder if the cartoonish smartphone game, and the big data that it generated, could serve as an avenue for scientific research.

Fig 1 from the paper: Airport Scanner game screenshots

Figure 1 from the paper: Screenshots of Airport Scanner game’s x-ray baggage displays. Can you spot the illegal items?

Fortunately for Dr. Mitroff, Ben Sharpe, the CEO of the company that made Airport Scanner, was pleased to hear that his company’s game could not only provide entertainment but also benefit scientific inquiry. Sharpe had his programmer tweak Airport Scanner’s code so that anonymized gameplay data would automatically download to a server that Dr. Mitroff’s research team could access, and a fruitful collaboration began.

CC2.5 via Wikimedia Commons user Duke

A real x-ray baggage screening display. Can you spot the illegal items? From Wikimedia Commons user Duke, via CC-BY-2.5 license

Most recently, Dr. Mitroff has used Airport Scanner to study how we search for “ultra-rare” items, or items that appear in less than 1% of searches (pdf of paper published in Psychological Science). In regular laboratory studies of visual search, the rarest testable items appear 1% of the time. Because people’s attention spans are limited, it is difficult to ask people to perform more than a few hundred searches in the lab. Consequently, items that appear 1% of the time provide just a handful of datapoints per person, and items that appear less frequently are virtually impossible to study.

Airport Scanner, on the other hand, allowed Dr. Mitroff to study millions of searches, including those with ultra-rare items that appeared as infrequently as 0.08% of the time. Even with such low rates of appearance, the big data generated by Airport Scanner players provided hundreds to thousands of instances for each ultra-rare search – enough datapoints to draw valid statistical inferences.

Figure 3 from the paper: How often targets (illegal items) were detected plotted by how frequently they appeared in the game.

Figure 3 from the paper: How often targets (illegal items) were detected plotted by how frequently they appeared in the game.

It turns out that people are disproportionately terrible at finding ultra-rare items. While items that appeared in 1% to 3.7% of searches were found 92% of the time, ultra-rare items that appeared in less than 0.15% of searches were only found 27% of the time, even by experienced players. If you are a cancer patient with an ultra-rare cancer marker, or a Transportation Security Officer (TSO) searching for an ultra-rare terrorist threat in packed luggage, this low success rate is bad news with life-threatening implications.

Dr. Mitroff’s research points to a way to remedy this poor result for ultra-rare item searches: artificially increase the frequency of ultra-rare items and thus make them no longer ultra-rare. Airport scanners already project false illegal items onto luggage x-rays for TSOs to find. This keeps TSOs vigilant and provides performance feedback. By tweaking existing algorithms to project more ultra-rare items – more fake bombs and fewer fake forgotten pocketknives – Dr. Mitroff notes that we can change “how likely [TSOs] are to see something.” Similar techniques can be applied to cancer screenings to give radiologists more practice detecting ultra-rare cancer markers.

So, the next time you find yourself wasting time or procrastinating with a smartphone game, you can reassure yourself that you are not just wasting time – you are working to generate data that could benefit science, or even save lives.

 ResearchBlogging.orgMitroff, S., & Biggs, A. (2013). The Ultra-Rare-Item Effect: Visual Search for Exceedingly Rare Items Is Highly Susceptible to Error Psychological Science, 25 (1), 284-289 DOI: 10.1177/0956797613504221


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