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Author de Waal, F.B. openurl 
  Title Food transfers through mesh in brown capuchins Type Journal Article
  Year 1997 Publication Journal of comparative psychology (Washington, D.C. : 1983) Abbreviated Journal (up) J Comp Psychol  
  Volume 111 Issue 4 Pages 370-378  
  Keywords Animals; Cebus/*psychology; *Feeding Behavior; Female; Food Preferences/psychology; Male; *Motivation; Sex Factors; *Social Behavior; Social Environment  
  Abstract Capuchin monkeys (Cebus apella) share food even if their partner is behind a mesh restraint. Pairs of adult capuchins were moved into a test chamber in which 1 monkey received cucumber pieces for 20 min and the other received apple slices during the following 20 min. Tolerant transfers of food occurred reciprocally among females: The rate of transfer from Female B to A in the second test phase varied with the rate from Female A to B in the first test phase. Several social mechanisms may explain this reciprocity. Whereas this study does not contradict cognitively complex explanations (e.g., mental record keeping of given and received food), the results are consistent with a rather simple explanation: that food sharing reflects a combination of affiliative tendency and high tolerance. The study suggests that sharing mechanisms may be different for adult male capuchins, with males sharing food more readily and less discriminatingly than females.  
  Address Yerkes Primate Center, Emory University, Atlanta, Georgia 30329, USA. dewaal@emory.edu  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0735-7036 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:9419882 Approved no  
  Call Number refbase @ user @ Serial 198  
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Author Brosnan, S.F.; De Waal, F.B.M. doi  openurl
  Title Monkeys reject unequal pay Type Journal Article
  Year 2003 Publication Nature Abbreviated Journal (up) Nature  
  Volume 425 Issue 6955 Pages 297-299  
  Keywords Aging; Animals; Cebus/*psychology; Choice Behavior; *Cooperative Behavior; Female; Male; *Reward; Social Justice  
  Abstract During the evolution of cooperation it may have become critical for individuals to compare their own efforts and pay-offs with those of others. Negative reactions may occur when expectations are violated. One theory proposes that aversion to inequity can explain human cooperation within the bounds of the rational choice model, and may in fact be more inclusive than previous explanations. Although there exists substantial cultural variation in its particulars, this 'sense of fairness' is probably a human universal that has been shown to prevail in a wide variety of circumstances. However, we are not the only cooperative animals, hence inequity aversion may not be uniquely human. Many highly cooperative nonhuman species seem guided by a set of expectations about the outcome of cooperation and the division of resources. Here we demonstrate that a nonhuman primate, the brown capuchin monkey (Cebus apella), responds negatively to unequal reward distribution in exchanges with a human experimenter. Monkeys refused to participate if they witnessed a conspecific obtain a more attractive reward for equal effort, an effect amplified if the partner received such a reward without any effort at all. These reactions support an early evolutionary origin of inequity aversion.  
  Address Living Links, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329, USA. sbrosna@emory.edu  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1476-4687 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:13679918 Approved no  
  Call Number refbase @ user @ Serial 179  
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Author de Waal, F.B.M.; Davis, J.M. openurl 
  Title Capuchin cognitive ecology: cooperation based on projected returns Type Journal Article
  Year 2003 Publication Neuropsychologia Abbreviated Journal (up) Neuropsychologia  
  Volume 41 Issue 2 Pages 221-228  
  Keywords Animals; Attention; Cebus/*psychology; *Cooperative Behavior; Decision Making; Dominance-Subordination; Female; Male; *Motivation; Reaction Time; Reinforcement Schedule; *Social Behavior  
  Abstract Stable cooperation requires that each party's pay-offs exceed those available through individual action. The present experimental study on brown capuchin monkeys (Cebus apella) investigated if decisions about cooperation are (a) guided by the amount of competition expected to follow the cooperation, and (b) made instantaneously or only after a period of familiarization. Pairs of adult monkeys were presented with a mutualistic cooperative task with variable opportunities for resource monopolization (clumped versus dispersed rewards), and partner relationships (kin versus nonkin). After pre-training, each pair of monkeys (N=11) was subjected to six tests, consisting of 15 2 min trials each, with rewards available to both parties. Clumped reward distribution had an immediate negative effect on cooperation: this effect was visible right from the start, and remained visible even if clumped trials alternated with dispersed trials. The drop in cooperation was far more dramatic for nonkin than kin, which was explained by the tendency of dominant nonkin to claim more than half of the rewards under the clumped condition. The immediacy of responses suggests a decision-making process based on predicted outcome of cooperation. Decisions about cooperation thus take into account both the opportunity for and the likelihood of subsequent competition over the spoils.  
  Address Living Links, Yerkes Primate Center, Emory University, 954 N. Gatewood Road, Atlanta, GA 30322, USA. dewaal@emory.edu  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0028-3932 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:12459220 Approved no  
  Call Number refbase @ user @ Serial 182  
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