A banana is hung on a string inside the cage and a set of stairs placed in the cage leading up to the banana. Whenever a monkey goes up the stairs and grabs the banana, ice-cold water is poured on all the monkeys in the cage. Very soon, as the monkeys begin to associate touching the banana with being sprayed with ice-cold water they will try to prevent one another from trying to get the banana.
The cold water is then turned off and one monkey removed from the cage and replaced with another that doesn’t know anything about the cold water. This new monkey will inevitably try to get the banana, but the other four monkeys will attack him to stop him from doing so.
If another of the old monkeys is removed and replaced with a newcomer, this newcomer will try to grab the banana. The previous newcomer will gladly take part in beating him up together with the other monkeys in order to prevent him from climbing the stairs to the banana.
Slowly, all the original monkey can be replaced with new monkeys in this manner. The cage will now be totally filled with monkeys that know nothing about the ice-cold water, but they will all not try to get the banana and continue to attack any monkey that tries to do so. “No monkey ever again approaches the stairs. Why Not? Because as far as they know, that’s the way it’s always been around here. Don’t be a monkey. Challenge all assumptions.” These are Michalko’s words of advice.