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Author Ottoni, E.B.; de Resende, B.D.; Izar, P. doi  openurl
  Title (up) Watching the best nutcrackers: what capuchin monkeys (Cebus apella) know about others' tool-using skills Type Journal Article
  Year 2005 Publication Animal cognition Abbreviated Journal Anim. Cogn.  
  Volume 8 Issue 4 Pages 215-219  
  Keywords Animals; *Association Learning; Cebus/*psychology; *Feeding Behavior; Female; Male; Nuts; *Problem Solving  
  Abstract The present work is part of a decade-long study on the spontaneous use of stones for cracking hard-shelled nuts by a semi-free-ranging group of brown capuchin monkeys (Cebus apella). Nutcracking events are frequently watched by other individuals--usually younger, less proficient, and that are well tolerated to the point of some scrounging being allowed by the nutcracker. Here we report findings showing that the choice of observational targets is an active, non-random process, and that observers seem to have some understanding of the relative proficiency of their group mates, preferentially watching the more skilled nutcrackers, which enhances not only scrounging payoffs, but also social learning opportunities.  
  Address Laboratory of Cognitive Ethology, Department of Experimental Psychology, Institute of Psychology, University of Sao Paulo, Brazil. ebottoni@usp.br  
  Corporate Author Thesis  
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  Language English Summary Language Original Title  
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  Series Volume Series Issue Edition  
  ISSN 1435-9448 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:15719240 Approved no  
  Call Number refbase @ user @ Serial 355  
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Author Jordan, K.E.; Brannon, E.M. doi  openurl
  Title (up) Weber's Law influences numerical representations in rhesus macaques (Macaca mulatta) Type Journal Article
  Year 2006 Publication Animal Cognition Abbreviated Journal Anim. Cogn.  
  Volume 9 Issue 3 Pages 159-172  
  Keywords Animals; *Attention; *Discrimination (Psychology); Female; Macaca mulatta/*psychology; Mathematics; *Pattern Recognition, Visual; Perceptual Masking; *Problem Solving; Psychological Theory; Psychometrics  
  Abstract We present the results of two experiments that probe the ability of rhesus macaques to match visual arrays based on number. Three monkeys were first trained on a delayed match-to-sample paradigm (DMTS) to match stimuli on the basis of number and ignore continuous dimensions such as element size, cumulative surface area, and density. Monkeys were then tested in a numerical bisection experiment that required them to indicate whether a sample numerosity was closer to a small or large anchor value. Results indicated that, for two sets of anchor values with the same ratio, the probability of choosing the larger anchor value systematically increased with the sample number and the psychometric functions superimposed. A second experiment employed a numerical DMTS task in which the choice values contained an exact numerical match to the sample and a distracter that varied in number. Both accuracy and reaction time were modulated by the ratio between the correct numerical match and the distracter, as predicted by Weber's Law.  
  Address Department of Psychological & Brain Sciences, Center for Cognitive Neuroscience, Duke University, Box 90999, Durham, NC 27708, USA  
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  Language English Summary Language Original Title  
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  Series Volume Series Issue Edition  
  ISSN 1435-9448 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:16575587 Approved no  
  Call Number Equine Behaviour @ team @ Serial 2471  
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Author Lonsdorf, E.V. doi  openurl
  Title (up) What is the role of mothers in the acquisition of termite-fishing behaviors in wild chimpanzees (Pan troglodytes schweinfurthii)? Type Journal Article
  Year 2006 Publication Animal Cognition Abbreviated Journal Anim. Cogn.  
  Volume 9 Issue 1 Pages 36-46  
  Keywords Animals; Animals, Wild; *Behavior, Animal; Cooking and Eating Utensils; Feeding Behavior/*psychology; Female; *Imitative Behavior; Learning; Mothers/*psychology; Motor Skills; Pan troglodytes/*psychology; Problem Solving  
  Abstract This paper explores the role of maternal influences on the acquisition of a tool-using task in wild chimpanzees (Pan troglodytes schweinfurthii) in order to build on and complement previous work done in captivity. Young chimpanzees show a long period of offspring dependency on mothers and it is during this period that offspring learn several important skills, especially how to and on what to forage. At Gombe National Park, one skill that is acquired during dependency is termite-fishing, a complex behavior that involves inserting a tool made from the surrounding vegetation into a termite mound and extracting the termites that attack and cling to the tool. All chimpanzees observed at Gombe have acquired the termite-fishing skill by the age of 5.5 years. Since the mother is the primary source of information throughout this time period, I investigated the influence of mothers' individual termite-fishing characteristics on their offsprings' speed of acquisition and proficiency at the skill once acquired. Mother's time spent alone or with maternal family members, which is highly correlated to time spent termite-fishing, was positively correlated to offspring's acquisition of critical elements of the skill. I also investigated the specific types of social interactions that occur between mothers and offspring at the termite mound and found that mothers are highly tolerant to offspring, even when the behavior of the offspring may disrupt the termite-fishing attempt. However, no active facilitation by mothers of offsprings' attempts were observed.  
  Address Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, MN 55108, USA. elonsdorf@lpzoo.org  
  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 1435-9448 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:16195914 Approved no  
  Call Number Equine Behaviour @ team @ Serial 2480  
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