Chimpanzees are very smart animals. To challenge them mentally, we give them different tasks.
One of them is a maze like the one before you. We hide a nut or a grape in the center of maze, and the chimpanzees must then try to roll the reward out of a hole in the side.
We have to change the course of the mazes periodically, because once the chimps have solved them a few times, they find it all too easy.