Run to the falling elevator!
That's how I interprited these signs the first time I saw them. I talked to my roomates, and my suitmates, and a few of the guys, and everyone has admited to making the same mistake. Green is just not a color that gets used on indoor signage in the US. The runinng man I can understand as meaning that one needs to travel, and the arrows clearly mean this/that way, but the white boxes confused me. This campus is alone is covered in random staircases and changes of ground level, and it is relativly new and modern but there is only one elevator and it doesn't make much sense to have signs in the Mensa when the machine in question is in the dorm.
It wasn't until I saw a sign in a Metro station that had the word Uscita written on it next to the falling elevator sign that I realized that these were exit signs.