Chapter 10 Real-world search
You may remember that it was a technological problem that helped get psychologists going in studying capacity limits - the problem of fighter pilots having to deal with flying and monitoring things in the cockpit at the same time.
More recently, in the aftermath of the September 11 attacks on the U.S., a different problem with planes became prominent, causing governments to want to closely inspect passengers’ luggage.
In recent years, tens of thousands of workers around the world have spent hours every day doing one particular kind of visual search - baggage searches! These are the people that sit at airport scanners and search through scanner images for prohibited items.
This kind of search involves additional complications beyond those described in the previous chapter (9). In the searches of the previous chapter, participants only had to worry about finding one kind of target, for example a red vertical line. But airport workers have to keep in mind many targets - scisssors, knives, and lighters as well as guns.
Below you can see some examples of the baggage scan images they have to search.
Can you find the prohibited items in the bags above?
Which type of response time pattern do you think this kind of search would result in - parallel search or serial search? See the previous chapter 9 for a reminder of what this means.
10.1 Individual differences
Some questions for managers of airport security are:
- Do people improve much with training at detecting threats?
- How much do people improve?
- With enough training, can anyone be made into an expert and have a similar level of performance?
Ericson, Kravitz, and Mitroff (2017) investigated this by making a game out of airport scanner inspections:
When Ericson, Kravitz, and Mitroff (2017) plotted the data from users of the game, they discovered something important.
The horizontal axis is trial number, where “trial” means an individual try. The three lines are three different groups of people, those who start out (at trial 1) with relatively slow performance (top line), those who start out a bit faster (middle line) and those who start very fast (bottom line). Each group of players gets better from left to right - the more trials they participate in, the faster their response time.
It’s good that everyone learns with practice. What’s unfortunate, however, is that the curves do not converge - the slow people get much faster but the fast people get even faster, so the people who start out fast maintain their lead. In other words, the individual differences are stable.
From these results, the airport security managers might have some tentative answers to their three questions. What do you suggest for answers to the three questions?
10.2 Running, cycling, and driving are like continuous change blindness experiments
Ericson, Justin M., Dwight J. Kravitz, and Stephen R. Mitroff. 2017. “Visual Search: You Are Who You Are (+ A Learning Curve).” Perception 46 (12): 1434–41. https://doi.org/10.1177/0301006617721091.