elevators
a large office building in New York City had a problem in the mid 1900s. many people were complaining that the wait for elevators was too long. so they hired a queue expert to figure out the perfect position for elevators so as to reduce the wait.
should the elevator's go to the bottom floor when not in use? should one of them go to the top floor, and the other to the bottom? or perhaps they should wait in the middle floor?
numerous combinations were tried. and while waiting time reduced, people still complained.
the solution turned out not to be a scientific one, but a "human" one.
they installed mirrors by the elevators and complaints dramatically went down as people lost track of time looking at themselves while waiting.
and ever since most elevators around the world are surrounded by mirrors.