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| Author |
Call, J.; Hare, B.A.; Tomasello, M. |
| Title |
Chimpanzee gaze following in an object-choice task |
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Journal Article |
| Year |
1998 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
| Volume |
1 |
Issue |
2 |
Pages |
89-99 |
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Many primate species reliably track and follow the visual gaze of conspecifics and humans, even to locations above and behind the subject. However, it is not clear whether primates follow a human's gaze to find hidden food under one of two containers in an object-choice task. In a series of experiments six adult female chimpanzees followed a human's gaze (head and eye direction) to a distal location in space above and behind them, and checked back to the human's face when they did not find anything interesting or unusual. This study also assessed whether these same subjects would also use the human's gaze in an object-choice task with three types of occluders: barriers, tubes, and bowls. Barriers and tubes permitted the experimenter to see their contents (i.e., food) whereas bowls did not. Chimpanzees used the human's gaze direction to choose the tube or barrier containing food but they did not use the human's gaze to decide between bowls. Our findings allowed us to discard both simple orientation and understanding seeing-knowing in others as the explanations for gaze following in chimpanzees. However, they did not allow us to conclusively choose between orientation combined with foraging tendencies and understanding seeing in others. One interesting possibility raised by these results is that studies in which the human cannot see the reward at the time of subject choice may potentially be underestimating chimpanzees' social knowledge. |
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Equine Behaviour @ team @ |
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3165 |
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| Author |
Melis, A.P.; Hare, B.; Tomasello, M. |
| Title |
Engineering cooperation in chimpanzees: tolerance constraints on cooperation |
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Journal Article |
| Year |
2006 |
Publication |
Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
| Volume |
72 |
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2 |
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275-286 |
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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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refbase @ user @ |
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287 |
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Hare, B.; Tomasello, M. |
| Title |
Chimpanzees are more skilful in competitive than in cooperative cognitive tasks |
Type |
Journal Article |
| Year |
2004 |
Publication |
Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
| Volume |
68 |
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3 |
Pages |
571-581 |
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In a series of four experiments, chimpanzees, Pan troglodytes, were given two cognitive tasks, an object choice task and a discrimination task (based on location), each in the context of either cooperation or competition. In both tasks chimpanzees performed more skilfully when competing than when cooperating, with some evidence that competition with conspecifics was especially facilitatory in the discrimination location task. This is the first study to demonstrate a facilitative cognitive effect for competition in a single experimental paradigm. We suggest that chimpanzee cognitive evolution is best understood in its socioecological context. |
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584 |
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Tomasello, M.; Hare, B.; Agnetta, B. |
| Title |
Chimpanzees, Pan troglodytes, follow gaze direction geometrically |
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Journal Article |
| Year |
1999 |
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Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
| Volume |
58 |
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4 |
Pages |
769-777 |
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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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587 |
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Hare, B.; Addessi, E.; Call, J.; Tomasello, M.; Visalberghi, E. |
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Do capuchin monkeys, Cebus apella, know what conspecifics do and do not see? |
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Journal Article |
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2003 |
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Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
| Volume |
65 |
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1 |
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131-142 |
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Capuchin monkeys were tested in five experiments in which two individuals competed over food. When given a choice between retrieving a piece of food that was visible or hidden from the dominant, subordinate animals preferred to retrieve hidden food. This preference is consistent with the hypotheses that either (1) the subordinate knew what the dominant could and could not see or (2) the subordinate was monitoring the behaviour of the dominant and avoiding the piece of food that it approached. To test between these alternatives, we released subordinates with a slight head start forcing them to make their choice (between a piece of food hidden or visible to the dominant) before the dominant entered the area. Unlike chimpanzees, Pan troglodytes, subordinates that were given a head start did not preferentially approach hidden pieces of food first. Therefore, our experiments provide little support for the hypothesis that capuchin monkeys are sensitive to what another individual does or does not see. We compare our results with those obtained with chimpanzees in the same paradigm and discuss the evolution of primate social cognition. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved. |
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refbase @ user @ |
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586 |
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Hare, B.; Call, J.; Agnetta, B.; Tomasello, M. |
| Title |
Chimpanzees know what conspecifics do and do not see |
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Journal Article |
| Year |
2000 |
Publication |
Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
| Volume |
59 |
Issue |
4 |
Pages |
771-785 |
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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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refbase @ user @ |
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585 |
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Hare, B.; Tomasello, M. |
| Title |
Domestic Dogs (Canis familiaris) Use Human and Conspecific Social Cues to Locate Hidden Food |
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Journal Article |
| Year |
1999 |
Publication |
Journal of Comparative Psychology |
Abbreviated Journal |
J. Comp. Psychol. |
| Volume |
113 |
Issue |
2 |
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173-177 |
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Ten domestic dogs (Canis familiaris) of different breeds and ages were exposed to 2 different social cues indicating the location of hidden food, each provided by both a human informant and a conspecific informant (for a total of 4 different social cues). For the local enhancement cue, the informant approached the location where food was hidden and then stayed beside it. For the gaze and point cue, the informant stood equidistant between 2 hiding locations and bodily oriented and gazed toward the 1 in which food was hidden (the human informant also pointed). Eight of the 10 subjects, including the one 6-month-old juvenile, were above chance with 2 or more cues. Results are discussed in terms of the phylogenetic and ontogenetic processes by means of which dogs come to use social cues to locate food. |
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refbase @ user @ |
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590 |
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Tomasello, M.; Call, J.; Hare, B. |
| Title |
Five primate species follow the visual gaze of conspecifics |
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Journal Article |
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1998 |
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Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
| Volume |
55 |
Issue |
4 |
Pages |
1063-1069 |
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Individuals from five primate species were tested experimentally for their ability to follow the visual gaze of conspecifics to an outside object. Subjects were from captive social groups of chimpanzees,Pan troglodytes, sooty mangabeys,Cercocebus atys torquatus, rhesus macaques,Macaca mulatta, stumptail macaques,M. arctoides, and pigtail macaques,M. nemestrina. Experimental trials consisted of an experimenter inducing one individual to look at food being displayed, and then observing the reaction of another individual (the subject) that was looking at that individual (not the food). Control trials consisted of an experimenter displaying the food in an identical manner when the subject was alone. Individuals from all species reliably followed the gaze of conspecifics, looking to the food about 80% of the time in experimental trials, compared with about 20% of the time in control trials. Results are discussed in terms of both the proximate mechanisms that might be involved and the adaptive functions that might be served by gaze-following. |
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592 |
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Tomasello, M.; Hare, B.; Fogleman, T. |
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The ontogeny of gaze following in chimpanzees, Pan troglodytes, and rhesus macaques, Macaca mulatta |
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Journal Article |
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2001 |
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Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
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61 |
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2 |
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335-343 |
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Primates follow the gaze direction of conspecifics to outside objects. We followed the ontogeny of this social-cognitive skill for two species: rhesus macaques and chimpanzees. In the first two experiments, using both a cross-sectional and a longitudinal design, we exposed individuals of different ages to a human looking in a specified direction. Rhesus infants first began reliably to follow the direction of this gaze at the end of the early infancy period, at about 5.5 months of age. Chimpanzees did not reliably follow human gaze until 3-4 years; this corresponds to the latter part of the late infancy period for this species. In the third experiment we exposed individuals of the same two species to a human repeatedly looking to the same location (with no special object at that location) to see if subjects would learn to ignore the looks. Only adults of the two species diminished their gaze-following behaviour over trials. This suggests that in the period between infancy and adulthood individuals of both species come to integrate their gaze-following skills with their more general social-cognitive knowledge about other animate beings and their behaviour, and so become able to deploy their gaze-following skills in a more flexible manner. |
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Hare, B. |
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Can competitive paradigms increase the validity of experiments on primate social cognition? |
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Journal Article |
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2001 |
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Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
| Volume |
4 |
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3 |
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269-280 |
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Experiments vary in their ability to distinguish between competing hypotheses. In tests on primate cognition the majority of this variation is due to an experimenter's ability to test primates in valid settings while providing the adequate amount of experimental control. While experimenters studying primate cognition can use methods of control perfected in captivity, it is still very unclear how to design and then objectively evaluate the external validity of new experimental paradigms. I recommend that more effort be allocated to specify how to create relevant test settings for primates. Primate social life is highly competitive. This means that all aspects of primates themselves, including their cognitive abilities, have likely been shaped by the need to out-compete conspecifics. Based on this hypothesis, sophisticated cognitive abilities of primates might best be demonstrated in competitive contexts. Thus, it is suggested that one possible measure of validity is whether investigators integrate a competitive component into their experimental designs. To evaluate this methodological prediction I review the literature on chimpanzee perspective-taking as a case study including several recent studies that include a competitive component in their experimental designs. |
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Equine Behaviour @ team @ |
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3093 |
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