Ethologie

Une célèbre vidéo montre des chimpanzés battant des humains à plate couture à un jeu de mémoire visuelle. Il semble que les chimpanzés en question aient été très entrainés et les humains pas du tout. Avec des humains entrainés, il est suggéré ici que le résultat est inverse :

Do young chimpanzees have extraordinary working memory?
Peter Cookand & Margaret Wilson
Psychonomic Bulletin & Review, 2010

Cliquer pour accéder à PBR.17.4.599.pdf

Do chimpanzees have better spatial working memory than humans? In a previous report, a juvenile chimpanzee outper-formed 3 university students on memory for briefly displayed digits in a spatial array (Inoue & Matsuzawa, 2007). The au-thors described these abilities as extraordinary and likened the chimpanzee’s performance to eidetic memory. However, the chimpanzee received extensive practice on a non-time-pressured version of the task; the human subjects received none. Here we report that, after adequate practice, 2 university students sub-stantially outperformed the chimpanzee. There is no evidence for a superior or qualitatively different spatial memory system in chimpanzees

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Une autre vidéo, rendue célèbre par Franz de Waal montre un singe capucin refusant énergiquement une récompense, parce que son voisin, pour la même tâche, a reçu une récompense supérieure, semblant démontrer le sens de l’équité des singes capucins. Les chimpanzés sont réputés pour avoir le même comportement. Il semble que des tentatives de réplication ou des expérimentations plus subtiles n’arrivent pas à un résultat aussi évident, ou du moins pas à la même explication (équité vis-à-vis du voisin).

Social disappointment explains chimpanzees’ behaviour in the inequity aversion task
Engelmann et al.
Proceedings of the royal society B, 2017
https://royalsocietypublishing.org/doi/full/10.1098/rspb.2017.1502#RSPB20171502C25

Chimpanzees’ refusal of less-preferred food when an experimenter has previously provided preferred food to a conspecific has been taken as evidence for a sense of fairness. Here, we present a novel hypothesis—the social disappointment hypothesis—according to which food refusals express chimpanzees’ disappointment in the human experimenter for not rewarding them as well as they could have. We tested this hypothesis using a two-by-two design in which food was either distributed by an experimenter or a machine and with a partner present or absent. We found that chimpanzees were more likely to reject food when it was distributed by an experimenter rather than by a machine and that they were not more likely to do so when a partner was present. These results suggest that chimpanzees’ refusal of less-preferred food stems from social disappointment in the experimenter and not from a sense of fairness.

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The age at which young children show an aversion to inequitable resource distributions, especially those favoring themselves, is unclear. It is also unclear whether great apes, as humans’ nearest evolutionary relatives, have an aversion to inequitable resource distributions at all. Using a common methodology across species and child ages, the current two studies found that 3- and 4-year-old children (N = 64) not only objected when they received less than a collaborative partner but also sacrificed to equalize when they received more. They did neither of these things in a nonsocial situation, demonstrating the fundamental role of social comparison. In contrast, chimpanzees (N = 9) showed no aversion to inequitable distributions, only a concern for maximizing their own resources, with no differences between social and nonsocial conditions. These results underscore the unique importance for humans, even early in ontogeny, for treating others fairly, presumably as a way of becoming a cooperative member of one’s cultural group.

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We found no evidence for either form of inequity aversion in capuchin monkeys.

Subjects’ decisions were based on the food type that they were offered.

Capuchins do not respond to inequity in a task directly modelled on human inequity aversion studies.

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Even though there was no cost associated with expressing an equality preference, we found no evidence that capuchins differentiated between equal and unequal experimenters.

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Fairness in Non-human Primates?
Juliane Brauer & Daniel Hanus
Social justice research, 2012
https://link.springer.com/article/10.1007/s11211-012-0159-6

Humans have a sense of fairness, i.e. an interest in the ideal of equity. This sense allows them to compare their own efforts and subsequent outcomes with those of others, and thus to evaluate and react to inequity. The question is whether our closest living relatives, the non-human primates, show the behavioural characteristics that might qualify as necessary components to a sense of fairness, such as inequity aversion. In this article, we review the five different experimental approaches to studying behaviours related to fairness in non-human primates, including their underlying logic and main findings that represent the current state of research in this field. In the critical condition of all these studies, a subject and a conspecific partner have either to invest different efforts or receive different outcomes while observing each other. The main question is whether—and how—subjects react to unequal situations that humans would perceive as ‘unfair’. Taken together, the results from all five approaches provide only weak evidence for a sense of fairness in non-human primates. Although apes and monkeys are attentive to what the partner is getting, they do not seem to be able or motivated to compare their own efforts and outcomes with those of others at a human level. Even though the debate is still on-going, we believe that a full sense of fairness is not essential for cooperation. Obviously, apes and monkeys are capable of solving problems cooperatively, without a strong, humanlike sense of fairness. They are mainly interested in maximizing their own benefit, regardless of what others may receive. It is thus possible that a sense of fairness only exists rudimentarily in non-human primates.

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Aversion to violation of expectations of food distribution: the role of social tolerance and relative dominance in seven primate species
Amici et al.
Behaviour, 2012
https://www.eva.mpg.de/documents/Brill/Amici_Aversion_Behaviour_2012_1560838.pdf

In the ‘food distribution’ task, capuchin mon-keys and especially macaques showed their aversion by refusing to participate in most conditions,including the ones with equal food distribution. When dominants received more food than thepartner, subjects of all species maintained a comparable amount of proximity to the food source.

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Does inequity aversion depend on a frustration effect? A test with capuchin monkeys (Cebus apella)
Silberberg et al.
Animal cognition, 2009
https://link.springer.com/article/10.1007/s10071-009-0211-6

Brosnan and de Waal (Nature 425:297–299, 2003) reported that if a witness monkey saw a model monkey receive a high-value food, the witness was more inclined to reject a previously acceptable, but low-value food. Later work demonstrated that this alleged inequity aversion might be due to frustration induced by switching subjects from their role as models receiving a high-value food to the role of witnesses receiving a low-value food. In the present study, pairs of female capuchins exchanged a token for either a high- or a low-value food without switching their model–witness roles. Witnesses could exchange a token for a low-value food after an adjacent model had exchanged a token for the same food (Equity Condition) or for a high-value food (Inequity Condition). Failure- and latency-to-exchange measures showed that witnesses were unaffected by the food type offered to models (no inequity aversion). Moreover, models were unaffected by their history of food type offered (no frustration). These results join earlier work suggesting that alleged inequity effects depend on frustration-induction procedures. Furthermore, inequity effects sometimes fail to emerge because frustration induction in nonhuman primates is labile.

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Semble répliquer :

Attending to the Outcome of Others: Disadvantageous Inequity Aversion in Male Capuchin Monkeys (Cebusapella)
Grace E. Fletcher
American journal of primatology, 2008

Cliquer pour accéder à Fletcher_Attending_AmJPrim_2008_1554459.pdf

In this study, a modified Dictator game was used to investigate whether capuchins would exhibit either disadvantageous inequity aversion behavior or reference-dependent expectancy violation in social and nonsocial conditions, respectively. When given the choice between an equitable and an inequitable outcome, the subjects showed disadvantageous inequity aversion behavior, choosing the equitable outcome significantly more in the social condition. In the nonsocial condition, however, subjects did not show negative expectancy violation resulting from the formation of reference-dependent expectations, choosing the equitable outcome at chance levels. These results suggest that capuchins attend to differential payoffs and that they are averse to inequity, which is disadvantageous to themselves.

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Are Capuchin Monkeys (Cebus apella) Inequity Averse ?
Dubreuil et al.
Proceedings : biological science, 2006
https://www.jstor.org/stable/25223435?seq=1

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Capuchin monkeys, inequity aversion, and the frustration effect.
Roma et al.
American psychological association, 2006
https://psycnet.apa.org/buy/2006-03207-008

Each of 4 female capuchin monkeys (« model ») was paired with another female capuchin (« witness ») in an adjacent cage. In Phases 1 and 3, a model could remove a grape from the experimenter’s hand while the witness watched. The witness was then offered a slice of cucumber, a less preferred food. Trials alternated between subjects 50 times, defining a session. In Phases 2 and 4, both were offered cucumber. Witness rejections of cucumber were infrequent and were not dependent on whether models received grape or cucumber. When models were offered cucumber, they rejected it at higher rates than did witnesses. These results fail to support findings of Brosnan and de Waal. An account based on the frustration effect accommodates these results and those of Brosnan and de Waal.

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Inequity aversion in capuchins ?
Joseph Henrich
Nature, 2004
https://www.nature.com/articles/428139a

Brosnan and de Waal¹ have shown that capuchin monkeys are more likely to reject a cucumber slice after seeing that another capuchin has received a more attractive grape. In interpreting this finding, the authors make a link to work in humans on ‘inequity aversion’ and suggest that capuchins, like humans, may reject rewards because they are averse to unequal pay-offs. Here I argue that this interpretation suffers from three problems: the results contradict the predictions of the inequity-aversion model that Bosnan and de Waal cite²; experimental results indicate that humans do not behave like capuchins in similar circumstances; and the available evidence does not suggest that inequity aversion is cross-culturally universal^3,4,5.

Bonobos

Les bonobos ont toujours été présentés comme les gentils chimpanzés, alors même que les données les concernant, surtout en milieu naturel, sont extrêmement limitées. Il n’est cependant pas certain qu’ils soient si angéliques, même si les études permettant d’en douter sont elles aussi fragiles.

Inter-group aggressive interaction patterns indicate male mate defense and female cooperation across bonobo groups at Wamba, Democratic Republic of the Congo
Tokuyama et al.
American Journal of Biological Anthropology, 2020

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Capuchin monkeys are not prosocial in an instrumental helping task
Skerry et al.
Animal Cognition, 2011

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Spontaneous prosocial choice by chimpanzees
Horner et al. (de Waal)
PNAS, 2011

Bonobos

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