The piano stairway: the “Fun Theory”
The Fun Theory, according to Volkswagen, is that if you make something that’s good for you into fun, more people will be likely to go along.
The theory seems to be borne out in a video that’s going viral: Working overnight, a team of technicians turned a stairway in the Odenplan subway station in Stockholm, Sweden, into a giant functioning piano keyboard. (Think Tom Hanks at F.A.O. Schwartz in “Big.”)
When travelers realized they could make music - or musical sounds, anyway - just by walking up and down the stairs, 66% more of them took the stairs instead of riding the escalator. Volkswagen may have hit on something. Watch it here: Piano Stairway

