The game "chimpanzee chess" is utilized to find out if chimpanzees can imagine what other chimpanzees are thinking about.
As you already might know from my blog I am a passionate chess player ... but did you also hear already of this other kind of 'chess' played by chimpanzees?
At the Max Planck Institute for Evolutionary Anthropology[1] in Leipzig researchers are making experiments to find out if great apes have the ability to understand what other persons (in this case: other great apes) are thinking. These studies reach back to 1978 and last until today.[2]
One way to gather new knowledge is letting the great apes play the so called "chimpanzee chess".
I will present you two versions of this game which both show the amazing cognitive skills of the great apes (as well as the creativity of the scientists to develop target-aimed experiments).
Source: Pixabay.
Version 1: the flat lying and the slanted caps.
Two chimpanzees in two different cages are sitting opposite to each other. Between them is placed a table. Then the researcher places a visual cover in front of chimpanzee A so that only chimpanzee B can observe what happens on the table now: the scientist places two banana pellets on a board on the table and covers them with small caps. However one of the banana pellets is lying in a hollow so that the cap lies flat. The other cap lies in a slanted position because of the food under it.
Now the the visual cover in front of chimpanzee A (who didn't see where the scientist put the pellets) is removed again and put in front of chimpanzee B. Chimpanzee A is allowed now to point on one of the two caps. He chooses the cap lying in a slanted position (slanted because of the food under it as he is correctly assuming).
Finally candidate B can choose ... and even if he still doesn't see anything he makes the correct decision: he points to the side of the flat lying cap and gets rewarded with a banana pellet! :) He only could meet the correct decision because of being able to imagine that chimpanzee A had probably chosen the cap lying in the slanted position, so that he himself had to choose the other one to get some food. Amazing, isn't it?
I offer you the abstract of that study[3] as well as a longer description of what has been done in German language.[4]
Version 2: the 'shell game'.
Be honest please: the 'chimpanzee chess' described above was way too complicated for most of us 'normal' Homo sapiens (OK, maybe part of the seemingly complexity could just be the result of my inabilitiy to describe it in appropriate English). :-)
Anyway, I will try to do better concerning version 2 of 'chimpanzee chees' by means of using images. This time the chimpanzees are sitting in front of three cups. Both great apes can observe that the researcher places a grape under the right cup (and then covers it again with the cup).
That's what both candidates know (a grape was placed under the right cup):
Then the researcher places a visual cover in front of chimpanzee A so that only chimpanzee B can observe what happens now: the scientist places another grape under the left cup.
That's what only chimpanzee B knows: under the right and the left cup there is a hidden grape:
Now a visual cover is placed in front of chimpanzee B, and chimpanzee A can make his choice. Of course he chooses the right cup, because he saw that a grape was placed there before (and didn't see that also under the left cup a grape was hidden).
Finally chimpanzee B can make his choice. His great cognitive achievement is that he can put himself in the shoes of chimpanzee A! He knows that chimpanzee A only has seen that the researcher has put a grape under the right cup and probably did choose the right side. He also don't know if something is lying under the cup in the middle. Therefore he chooses the left cup and gets his well deserved reward.
You can also find a description of the experiment in German language.[5]
Sources:
- https://www.mpg.de/eva-de
- http://www.eva.mpg.de/psycho/pdf/Call&Tomasello2008TICS.pdf
- http://www.pnas.org/content/108/7/3077.abstract
- https://www.dasgehirn.info/denken/im-kopf-der-anderen/schimpansen-schach
- http://www.rp-online.de/panorama/wissen/denkvermoegen-von-tieren-wird-unterschaetzt-aid-1.3800322