dbo:abstract
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- Inequity aversion in animals is the willingness to sacrifice material pay-offs for the sake of greater equality, something humans tend to do from early age. It manifests itself through negative responses when rewards are not distributed equally between animals. In controlled experiments it has been observed, in varying degrees, in capuchin monkeys, chimpanzees, macaques, marmosets, dogs, wolves, rats, crows and ravens. No evidence of the effect was found in tests with orangutans, owl monkeys, squirrel monkeys, tamarins, kea, and cleaner fish. Due to mixed results in experimental studies it may be that some bonobos, baboons, gibbons, and gorillas are inequity averse.Disadvantageous inequity aversion is most common, that is, the animal protests when it gets a lesser reward than another animal. But advantageous inequity aversion has been observed as well, in chimpanzees, baboons and capuchins: the animal protests when it gets a better reward. Scientists believe that sensitivity to inequity co-evolved with the ability to cooperate, as it helps to sustain benefitting from cooperation. The first researchers to discover inequity aversion in animals were Sarah Brosnan and Frans de Waal, in an experiment with five capuchins, described in a 2003 article in Nature. The monkeys tended to refuse to participate in a food-for-token exchange task once they saw another monkey get rewarded more desirable food for equal effort. On some occasions they threw the food back at the human experimenter. Dozens of studies have been undertaken since. A few experimental paradigms have been used to test inequity aversion. The exchange is most common. Here animals need to hand over a token to the human experimenter in exchange for a food reward. The results and findings are mixed. In terms of refusal rates being higher in inequity conditions than equity, there is substantial variation across species, across studies, and even across individuals within the same studies. Some researchers have argued that small differences in experimental setup can make the effect disappear. This is the case, for instance, if the animals are not side by side and do not have good visibility of their partner and their actions, or if there is no task and the animals are simply given food. In some species the females do not refuse inferior rewards but the males do; in some other species it was the other way around. Due to low sample sizes, not all studies controlled for sex and rank. (en)
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rdfs:comment
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- Inequity aversion in animals is the willingness to sacrifice material pay-offs for the sake of greater equality, something humans tend to do from early age. It manifests itself through negative responses when rewards are not distributed equally between animals. In controlled experiments it has been observed, in varying degrees, in capuchin monkeys, chimpanzees, macaques, marmosets, dogs, wolves, rats, crows and ravens. No evidence of the effect was found in tests with orangutans, owl monkeys, squirrel monkeys, tamarins, kea, and cleaner fish. Due to mixed results in experimental studies it may be that some bonobos, baboons, gibbons, and gorillas are inequity averse.Disadvantageous inequity aversion is most common, that is, the animal protests when it gets a lesser reward than another anima (en)
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