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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 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 Brosnan, S.F.; de Waal, F.B.M. doi  openurl
  Title Socially learned preferences for differentially rewarded tokens in the brown capuchin monkey (Cebus apella) Type Journal Article
  Year 2004 Publication Journal of comparative psychology (Washington, D.C. : 1983) Abbreviated Journal J Comp Psychol  
  Volume 118 Issue 2 Pages 133-139  
  Keywords Animals; Behavior, Animal; Cebus; *Choice Behavior; Female; *Learning; Male; *Reward; *Social Behavior  
  Abstract Social learning is assumed to underlie traditions, yet evidence indicating social learning in capuchin monkeys (Cebus apella), which exhibit traditions, is sparse. The authors tested capuchins for their ability to learn the value of novel tokens using a previously familiar token-exchange economy. Capuchins change their preferences in favor of a token worth a high-value food reward after watching a conspecific model exchange 2 differentially rewarded tokens, yet they fail to develop a similar preference after watching tokens paired with foods in the absence of a conspecific model. They also fail to learn that the value of familiar tokens has changed. Information about token value is available in all situations, but capuchins seem to pay more attention in a social situation involving novel tokens.  
  Address Living Links Center, Yerkes National Primate Research Center, and Graduate Division of Biological and Biomedical Sciences, Emory University, Atlanta, GA 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 0735-7036 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:15250800 Approved no  
  Call Number refbase @ user @ Serial 173  
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Author Brosnan, S.F.; Freeman, C.; De Waal, F.B.M. doi  openurl
  Title Partner's behavior, not reward distribution, determines success in an unequal cooperative task in capuchin monkeys Type Journal Article
  Year 2006 Publication American journal of primatology Abbreviated Journal Am. J. Primatol.  
  Volume 68 Issue 7 Pages 713-724  
  Keywords Animals; Behavior, Animal/*physiology; Cebus/*physiology; *Cooperative Behavior; Female; Food Preferences/physiology; Male; *Reward  
  Abstract It was recently demonstrated that capuchin monkeys notice and respond to distributional inequity, a trait that has been proposed to support the evolution of cooperation in the human species. However, it is unknown how capuchins react to inequitable rewards in an unrestricted cooperative paradigm in which they may freely choose both whether to participate and, within the bounds of their partner's behavior, which reward they will receive for their participation. We tested capuchin monkeys with such a design, using a cooperative barpull, which has been used with great success in the past. Contrary to our expectations, the equity of the reward distribution did not affect success or pulling behavior. However, the behavior of the partner in an unequal situation did affect overall success rates: pairs that had a tendency to alternate which individual received the higher-value food in unequal reward situations were more than twice as successful in obtaining rewards than pairs in which one individual dominated the higher-value food. This ability to equitably distribute rewards in inherently biased cooperative situations has profound implications for activities such as group hunts, in which multiple individuals work together for a single, monopolizable reward.  
  Address Living Links Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia, 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 0275-2565 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:16786518 Approved no  
  Call Number refbase @ user @ Serial 160  
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Author Clement, T.S.; Feltus, J.R.; Kaiser, D.H.; Zentall, T.R. openurl 
  Title “Work ethic” in pigeons: reward value is directly related to the effort or time required to obtain the reward Type Journal Article
  Year 2000 Publication Psychonomic bulletin & review Abbreviated Journal Psychon Bull Rev  
  Volume 7 Issue 1 Pages 100-106  
  Keywords Animals; Behavior, Animal/*physiology; Cognition/physiology; Columbidae; Discrimination Learning/physiology; Female; Male; Reinforcement (Psychology); *Reward; Time Factors  
  Abstract Stimuli associated with less effort or with shorter delays to reinforcement are generally preferred over those associated with greater effort or longer delays to reinforcement. However, the opposite appears to be true of stimuli that follow greater effort or longer delays. In training, a simple simultaneous discrimination followed a single peck to an initial stimulus (S+FR1 S-FR1) and a different simple simultaneous discrimination followed 20 pecks to the initial stimulus (S+FR20 S-FR20). On test trials, pigeons preferred S+FR20 over S+FR1 and S-FR20 over S-FR1. These data support the view that the state of the animal immediately prior to presentation of the discrimination affects the value of the reinforcement that follows it. This contrast effect is analogous to effects that when they occur in humans have been attributed to more complex cognitive and social factors.  
  Address University of Kentucky, Lexington, USA  
  Corporate Author Thesis  
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1069-9384 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:10780022 Approved no  
  Call Number refbase @ user @ Serial 248  
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