File:DoorianFruit.png

an example of the 'Doorian Fruit' which is the name of this box. in image A, it can open by one method and in B it opens by a different method. This box was used to test whether monkeys learned to use it one way or another. since the opening mechanism is not easier to open by either method, the only influences on opening the monkey would either be preference or learning. if most of all monkeys do it the same way, this would effectively rule out preference. The image comes from There is no better image for this.