This could only be achieved by the chimps prodding sticks into holes in the pipes to change the direction of the dice.
The same task was also carried out with Brazil nuts, but the exit chamber removed so that the nuts fell out as a tasty treat for the chimps, according to the study published by the Zoological Society of London (ZSL).
“We noticed that the chimps were keen to complete the puzzle regardless of whether or not they received a food reward. This strongly suggests they get similar feelings of satisfaction to humans who often complete brain games for a feel-good reward,” ZSL researcher Fay Clark said.
The adult family group of chimpanzees at ZSL Whipsnade Zoo consist of two females and four males, three of which are half-brothers: Phil, Grant and Elvis.
This study allowed them to solve a novel cognitive problem in their normal social grouping, by choice. In addition, the chimpanzees were not trained on how to use the device.
“For chimps in the wild, this task is a little bit like foraging for insects or honey inside a tree stump or a termite mound; except more challenging because the dice do not stick to the tool,” Fay said in a statement.