VIP Kiosk Passenger User Interface

How did we get a broad demographic of passengers to stand still for 14 seconds while their shoes were being scanned for explosives?
We conducted multiple, real-time usability studies, on-site with real passengers at several different airports. We quickly discovered visual prompts alone were not enough, but a combination of subtle sounds, and the distraction of five carefully timed screening tasks did the trick.
After multiple iterations we were able to successfully eliminate foot faults, reduce the need for personnel, all while achieving TSA certification.