Comments on: Do chimpanzees care about fairness? The jury’s out

By: paul barnsley

paul barnsley — Thu, 17 Jan 2013 10:18:10 +0000

I don’t believe the failure of any recipient chimps to reject an offer is fatal to demonstrating an inclination towards fairness in the offering chimps.

There is a variant of the ultimatum game used in similar experiments on humans called “the dictator game”, under the rules of which the offerer proposes a split on which the recipient has no say whatsoever. Evidence from the dictator game in humans suggests non-zero average allocations to the (powerless) recipient, and this is taken as evidence of nonstrategic concern for fairness on the part of the offerer.

At a minimum we may have evidence of human-like dictator game behaviour here, even if the chimps do not understand that they are playing an ultimatum game.

By: Dan in Euroland

Dan in Euroland — Tue, 15 Jan 2013 22:12:11 +0000

DrugMoneky,

There are some pretty serious criticism of the ultimatum game in humans. For an overview of the deabate see: http://www.wiwi.uni-bonn.de/shaked/rhetoric/

By: DrugMonkey

DrugMonkey — Tue, 15 Jan 2013 20:55:29 +0000

Do all humans exhibit “fairness”? In all situations? What proportion of them? Can self-interest masquerade as “fairness”?

These are but a few of the reasons the comparative cognition effort is ridiculously a-scientific.

(nice new blog, btw, Ed. sorry I didn’t make the very first comment on this version!)

By: AMog

AMog — Tue, 15 Jan 2013 18:48:33 +0000

Great write up. However, I’m slightly confused about one thing. Grant that Proctor failed to create a true ultimatum game set-up in which first player chimpanzees understood that second players could reject the split they propose. I would think that the this only strengthens the evidence that chimpanzees care about fairness! After all, in a true ultimatum game, there is always the possibility that the first player chooses an equal split for purely strategic reasons. (For human beings, evidence actually suggests that first player offers are more generous than strategic reasoning would predict.) If Proctor found that first players were choosing egalitarian splits but there is some doubt that they understood that the second player might reject an unequal split, this only strengthens the evidence that first player chimpanzees were motivated by fairness: after all, they would in that case have no strategic reason to offer a fair split. What her evidence fails to confirm is that chimpanzees react to unfairness with something like spite. Or am I missing something?

By: SP

SP — Tue, 15 Jan 2013 14:07:27 +0000

There appear to be lots of problems with this. First this “And all four of them chose that token more often in the ultimatum game than in a straight preference test, when their choice dictated their reward irrespective of what a responder did.” Suggests that the chimps don’t really understand what they are doing or don’t unabiguosly prefer more bananas to less bananas, otherwise why would the not pick the ‘more bananas’ token all the time? Second “Proctor played the game with three pairs of chimps, one of which swapped roles as proposer and responder.” Swapping roles fundamentally alters the nature of the game. It becomes a repeat play prisoners’ dilema rather than a simple prisoners’ dilema, and as a result cooperation (positive start tit-for-tat) potentially becomes a rational strategy. Finally, I think you are a little unfair to Jensen, his critique that it is the response rather than the offer which is key is clearly correct — it is the ‘irrational’ (in terms of short term self interest) behaviour of the respondent in refusing an offer which leaves him better off but which is percieved as unfair which is the really telling result in humans. Jensen seems to have clear evidence that this is not happening in chimps, this is proof of absence, unelss you reject the evidence. My suspicion is that you are fonder of chimps than me. Still wonderful writing about facinating research though. Thanks.

By: Nathan Myers

Nathan Myers — Tue, 15 Jan 2013 07:38:04 +0000

Give the first chimp two tokens, to put one in a slot and give the other to the second chimp. Have the second chimp put the token in one slot (accept) or other (reject), in full view of the first. Start by putting a token in the first chimp’s slot and giving the other token directly to the second chimp, while the first watches.

Issue tokens only once per 15 minutes.

By: Kelvin Helmholtz

Kelvin Helmholtz — Mon, 14 Jan 2013 23:27:44 +0000

“In both cases, when proposers needed to cooperate with responders, they became more likely to offer an equal split, rather than trying to hog the rewards for themselves.”

Hog as a perjoritive in this article? Liberate your language, National Geographic.