The public collides uncomfortably with the private in the bathroom as it does nowhere else. How psychology, gender roles, and design explain the distinctive way we behave in the world’s stalls:

The vulnerability and exposure of using a urinal seems to create the need for additional social boundaries, in place of even “flimsy” physical ones. A famous, though ethically questionable, study from 1976 found that invading this socially agreed-upon bubble of personal space made it much more difficult for men to pee. To discover this, one researcher hid in a bathroom stall and watched men at the urinals through a periscope, timing the “delay and persistence” of urination when a confederate came into the bathroom and stood right next to or one urinal removed from the unknowing participant. The closer the confederate was, the longer the delay before the man was able to go, and the less time he peed overall. Whether he would have been able to go at all had he known someone was spying on him through a periscope, no one can say.