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Author Melis, A.P.; Hare, B.; Tomasello, M. url  doi
openurl 
  Title Engineering cooperation in chimpanzees: tolerance constraints on cooperation Type Journal Article
  Year 2006 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 72 Issue 2 Pages 275-286  
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  Abstract (up) The cooperative abilities of captive chimpanzees, Pan troglodytes, in experiments do not match the sophistication that might be predicted based on their naturally occurring cooperative behaviours. This discrepancy might partly be because in previous experiments potential chimpanzee cooperators were partnered without regard to their social relationship. We investigated the ability of chimpanzee dyads to solve a physical task cooperatively in relation to their interindividual tolerance levels. Pairs that were most capable of sharing food outside the test were also able to cooperate spontaneously (by simultaneously pulling two ropes) to obtain food. In contrast, pairs that were less inclined to share food outside of the test were unlikely to cooperate. Furthermore, previously successful subjects stopped cooperating when paired with a less tolerant partner, even when the food rewards were presented in a dispersed and divisible form to reduce competition between subjects. These results show that although chimpanzees are capable of spontaneous cooperation in a novel instrumental task, tolerance acts as a constraint on their ability to solve such cooperative problems. This finding highlights the importance of controlling such social constraints in future experiments on chimpanzee cooperation, and suggests that the evolution of human-like cooperative skills might have been preceded by the evolution of a more egalitarian social system and a more human-like temperament.  
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  Call Number refbase @ user @ Serial 287  
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Author Liebal, K.; Pika, S.; Tomasello, M. doi  openurl
  Title Social communication in siamangs (Symphalangus syndactylus): use of gestures and facial expressions Type Journal Article
  Year 2004 Publication Primates Abbreviated Journal Primates  
  Volume 45 Issue 1 Pages 41-57  
  Keywords Age Factors; *Animal Communication; Animals; Animals, Zoo/*physiology; *Cognition; Female; Hylobates/*physiology; *Kinesics; Male; Sex Factors; *Social Behavior; Video Recording  
  Abstract (up) The current study represents the first systematic investigation of the social communication of captive siamangs (Symphalangus syndactylus). The focus was on intentional signals, including tactile and visual gestures, as well as facial expressions and actions. Fourteen individuals from different groups were observed and the signals used by individuals were recorded. Thirty-one different signals, consisting of 12 tactile gestures, 8 visual gestures, 7 actions, and 4 facial expressions, were observed, with tactile gestures and facial expressions appearing most frequently. The range of the signal repertoire increased steadily until the age of six, but declined afterwards in adults. The proportions of the different signal categories used within communicative interactions, in particular actions and facial expressions, also varied depending on age. Group differences could be traced back mainly to social factors or housing conditions. Differences in the repertoire of males and females were most obvious in the sexual context. Overall, most signals were used flexibly, with the majority performed in three or more social contexts and almost one-third of signals used in combination with other signals. Siamangs also adjusted their signals appropriately for the recipient, for example, using visual signals most often when the recipient was already attending (audience effects). These observations are discussed in the context of siamang ecology, social structure, and cognition.  
  Address Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany. liebal@eva.mpg.de  
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  Language English Summary Language Original Title  
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  Series Volume Series Issue Edition  
  ISSN 0032-8332 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:14655035 Approved no  
  Call Number Equine Behaviour @ team @ Serial 2812  
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Author Call, J.; Carpenter, M.; Tomasello, M. doi  openurl
  Title Copying results and copying actions in the process of social learning: chimpanzees (Pan troglodytes) and human children (Homo sapiens) Type Journal Article
  Year 2005 Publication Animal Cognition Abbreviated Journal Anim. Cogn.  
  Volume 8 Issue 3 Pages 151-163  
  Keywords Animals; Child Behavior; Child, Preschool; *Concept Formation; Female; Humans; *Imitative Behavior; *Learning; Male; Pan troglodytes; *Problem Solving; Psychomotor Performance; Random Allocation; *Social Environment; Species Specificity  
  Abstract (up) There is currently much debate about the nature of social learning in chimpanzees. The main question is whether they can copy others' actions, as opposed to reproducing the environmental effects of these actions using their own preexisting behavioral strategies. In the current study, chimpanzees (Pan troglodytes) and human children (Homo sapiens) were shown different demonstrations of how to open a tube-in both cases by a conspecific. In different experimental conditions, demonstrations consisted of (1) action only (the actions necessary to open the tube without actually opening it); (2) end state only (the open tube, without showing any actions); (3) both of these components (in a full demonstration); or (4) neither of these components (in a baseline condition). In the first three conditions subjects saw one of two different ways that the tube could open (break in middle; caps off ends). Subjects' behavior in each condition was assessed for how often they opened the tube, how often they opened it in the same location as the demonstrator, and how often they copied the demonstrator's actions or style of opening the tube. Whereas chimpanzees reproduced mainly the environmental results of the demonstrations (emulation), human children often reproduced the demonstrator's actions (imitation). Because the procedure used was similar in many ways to the procedure that Meltzoff (Dev Psych 31:1, 1995) used to study the understanding of others' unfulfilled intentions, the implications of these findings with regard to chimpanzees' understanding of others' intentions are also discussed.  
  Address Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103, Leipzig, Germany. call@eva.mpg.de  
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  Series Volume Series Issue Edition  
  ISSN 1435-9448 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:15490290 Approved no  
  Call Number Equine Behaviour @ team @ Serial 2504  
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Author Call, J.; Brauer, J.; Kaminski, J.; Tomasello, M. doi  openurl
  Title Domestic dogs (Canis familiaris) are sensitive to the attentional state of humans Type Journal Article
  Year 2003 Publication Journal of comparative psychology (Washington, D.C. : 1983) Abbreviated Journal J Comp Psychol  
  Volume 117 Issue 3 Pages 257-263  
  Keywords Animals; *Appetitive Behavior; *Attention; *Bonding, Human-Pet; *Concept Formation; Cues; Dogs/*psychology; Female; Humans; *Inhibition (Psychology); Male; Nonverbal Communication  
  Abstract (up) Twelve domestic dogs (Canis familiaris) were given a series of trials in which they were forbidden to take a piece of visible food. In some trials, the human continued to look at the dog throughout the trial (control condition), whereas in others, the human (a) left the room, (b) turned her back, (c) engaged in a distracting activity, or (d) closed her eyes. Dogs behaved in clearly different ways in most of the conditions in which the human did not watch them compared with the control condition, in which she did. In particular, when the human looked at them, dogs retrieved less food, approached it in a more indirect way, and sat (as opposed to laid down) more often than in the other conditions. Results are discussed in terms of domestic dogs' social-cognitive skills and their unique evolutionary and ontogenetic histories.  
  Address Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany. call@eva.mpg.de  
  Corporate Author Thesis  
  Publisher Place of Publication Washington, D.C. : 1983 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:14498801 Approved no  
  Call Number refbase @ user @ Serial 713  
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Author Tomasello, M.; Hare, B.; Agnetta, B. url  openurl
  Title Chimpanzees, Pan troglodytes, follow gaze direction geometrically Type Journal Article
  Year 1999 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 58 Issue 4 Pages 769-777  
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  Abstract (up) Two experiments on chimpanzee gaze following are reported. In the first, chimpanzee subjects watched as a human experimenter looked around various types of barriers. The subjects looked around each of the barriers more when the human had done so than in a control condition (in which the human looked in another direction). In the second experiment, chimpanzees watched as a human looked towards the back of their cage. As they turned to follow the human's gaze a distractor object was presented. The chimpanzees looked at the distractor while still following the human's gaze to the back of the cage. These two experiments effectively disconfirm the low-level model of chimpanzee gaze following in which it is claimed that upon seeing another animate being's gaze direction chimpanzees simply turn in that direction and look around for something interesting. Rather, they support the hypothesis that chimpanzees follow the gaze direction of other animate beings geometrically to specific locations, in much the same way as human infants. The degree to which chimpanzees have a mentalistic interpretation of the gaze and/or visual experience of others is still an open question.  
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  Notes Approved no  
  Call Number refbase @ user @ Serial 587  
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Author Itakura, S.; Agnetta, B.; Hare, B.; Tomasello, M. doi  openurl
  Title Chimpanzee Use of Human and Conspecific Social Cues to Locate Hidden Food Type Journal Article
  Year 2001 Publication Developmental Science Abbreviated Journal Dev Sci  
  Volume 2 Issue 2 Pages 448 - 456  
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  Abstract (up) Two studies are reported in which chimpanzees attempted to use social cues to locate hidden food in one of two possible hiding places. In the first study four chimpanzees were exposed to a local enhancement cue (the informant approached and looked to the location where food was hidden and then remained beside it) and a gaze/point cue (the informant gazed and manually pointed towards the location where the food was hidden). Each cue was given by both a human informant and a chimpanzee informant. In the second study 12 chimpanzees were exposed to a gaze direction cue in combination with a vocal cue (the human informant gazed to the hiding location and produced one of two different vocalizations – a 'food-bark' or a human word-form). The results were – (i) all subjects were quite skillful with the local enhancement cue, no matter who produced it; (ii) few subjects were skillful with the gaze/point cue, no matter who produced it (most of these being individuals who had been raised in infancy by humans); and (iii) most subjects were skillful when the human gazed and vocalized at the hiding place, with little difference between the two types of vocal cue. Findings are discussed in terms of chimpanzees' apparent need for additional cues, over and above gaze direction cues, to indicate the presence of food.  
  Address Department of Psychology and Yerkes Regional Primate Research Center, Emory University, USA DOI – 10.1111/1467-7687.00089  
  Corporate Author Thesis  
  Publisher Place of Publication Blackwell Publishers Ltd. 1999 Editor  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 4973  
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Author Hare, B.; Call, J.; Tomasello, M. doi  openurl
  Title Do chimpanzees know what conspecifics know? Type Journal Article
  Year 2001 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 61 Issue 1 Pages 139-151  
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  Abstract (up) We conducted three experiments on social problem solving by chimpanzees, Pan troglodytes. In each experiment a subordinate and a dominant individual competed for food, which was placed in various ways on the subordinate's side of two opaque barriers. In some conditions dominants had not seen the food hidden, or food they had seen hidden was moved elsewhere when they were not watching (whereas in control conditions they saw the food being hidden or moved). At the same time, subordinates always saw the entire baiting procedure and could monitor the visual access of their dominant competitor as well. If subordinates were sensitive to what dominants did or did not see during baiting, they should have preferentially approached and retrieved the food that dominants had not seen hidden or moved. This is what they did in experiment 1 when dominants were either uninformed or misinformed about the food's location. In experiment 2 subordinates recognized, and adjusted their behaviour accordingly, when the dominant individual who witnessed the hiding was replaced with another dominant individual who had not witnessed it, thus demonstrating their ability to keep track of precisely who has witnessed what. In experiment 3 subordinates did not choose consistently between two pieces of hidden food, one of which dominants had seen hidden and one of which they had not seen hidden. However, their failure in this experiment was likely to be due to the changed nature of the competition under these circumstances and not to a failure of social-cognitive skills. These findings suggest that at least in some situations (i.e. competition with conspecifics) chimpanzees know what conspecifics have and have not seen (do and do not know), and that they use this information to devise effective social-cognitive strategies. Copyright 2001 The Association for the Study of Animal Behaviour.  
  Address Department of Psychology and Yerkes Regional Primate Research Center, Emory University  
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0003-3472 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:11170704 Approved no  
  Call Number refbase @ user @ Serial 588  
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Author Buttelmann, D.; Call, J.; Tomasello, M. doi  openurl
  Title Behavioral cues that great apes use to forage for hidden food Type Journal Article
  Year 2007 Publication Animal Cognition Abbreviated Journal Anim. Cogn.  
  Volume Issue Pages  
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  Abstract (up) We conducted three studies to examine whether the four great ape species (chimpanzees, bonobos, gorillas, and orangutans) are able to use behavioral experimenter-given cues in an object-choice task. In the subsequent experimental conditions subjects were presented with two eggs, one of which contained food and the other did not. In Study 1 the experimenter examined both eggs by smelling or shaking them, but only made a failed attempt to open (via biting) the egg containing food. In a control condition, the experimenter examined and attempted to open both eggs, but in reverse order to control for stimulus enhancement. The apes significantly preferred the egg that was first examined and then bitten, but had no preference in a baseline condition in which there were no cues. In Study 2, we investigated whether the apes could extend this ability to cues not observed in apes so far (i.e., attempting to pull apart the egg), as well as whether they made this discrimination based on the function of the action the experimenter performed. Subjects significantly preferred eggs presented with this novel cue, but did not prefer eggs presented with a novel but functionally irrelevant action. In Study 3, apes did not interpret human actions as cues to food-location when they already knew that the eggs were empty. Thus, great apes were able to use a variety of experimenter-given cues associated with foraging actions to locate hidden food and thereby were partially sensitive to the general purpose underlying these actions.  
  Address Department of Developmental and Comparative Psychology, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103, Leipzig, Germany, buttelmann@eva.mpg.de  
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  ISSN 1435-9448 ISBN Medium  
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  Notes PMID:17534674 Approved no  
  Call Number Equine Behaviour @ team @ Serial 2396  
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Author Schneider, A.-C.; Melis, A.P.; Tomasello, M. url  doi
openurl 
  Title How chimpanzees solve collective action problems Type Journal Article
  Year 2012 Publication Proceedings of the Royal Society B: Biological Sciences Abbreviated Journal  
  Volume Issue Pages  
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  Abstract (up) We presented small groups of chimpanzees with two collective action situations, in which action was necessary for reward but there was a disincentive for individuals to act owing to the possibility of free-riding on the efforts of others. We found that in simpler scenarios (experiment 1) in which group size was small, there was a positive relationship between rank and action with more dominant individuals volunteering to act more often, particularly when the reward was less dispersed. Social tolerance also seemed to mediate action whereby higher tolerance levels within a group resulted in individuals of lower ranks sometimes acting and appropriating more of the reward. In more complex scenarios, when group size was larger and cooperation was necessary (experiment 2), overcoming the problem was more challenging. There was highly significant variability in the action rates of different individuals as well as between dyads, suggesting success was more greatly influenced by the individual personalities and personal relationships present in the group.  
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  Call Number Equine Behaviour @ team @ Serial 5629  
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Author Hare, B.; Call, J.; Agnetta, B.; Tomasello, M. url  doi
openurl 
  Title Chimpanzees know what conspecifics do and do not see Type Journal Article
  Year 2000 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 59 Issue 4 Pages 771-785  
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  Abstract (up) We report a series of experiments on social problem solving in chimpanzees, Pan troglodytes. In each experiment a subordinate and a dominant individual were put into competition over two pieces of food. In all experiments dominants obtained virtually all of the foods to which they had good visual and physical access. However, subordinates were successful quite often in three situations in which they had better visual access to the food than the dominant, for example, when the food was positioned so that only the subordinate (and not the dominant) could see it. In some cases, the subordinate might have been monitoring the behaviour of the dominant directly and simply avoided the food that the dominant was moving towards (which just happened to be the one it could see). In other cases, however, we ruled out this possibility by giving subordinates a small headstart and forcing them to make their choice (to go to the food that both competitors could see, or the food that only they could see) before the dominant was released into the area. Together with other recent studies, the present investigation suggests that chimpanzees know what conspecifics can and cannot see, and, furthermore, that they use this knowledge to devise effective social-cognitive strategies in naturally occurring food competition situations.  
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  Notes Approved no  
  Call Number refbase @ user @ Serial 585  
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