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Hare, B., Rosati, A., Kaminski, J., Bräuer, J., Call, J., & Tomasello, M. (2010). The domestication hypothesis for dogs' skills with human communication: a response to Udell et al. (2008) and Wynne et al. (2008). Anim Behav, 79.
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Warneken, F., Hare, B., Melis, A. P., Hanus, D., & Tomasello, M. (2007). Spontaneous Altruism by Chimpanzees and Young Children. PLoS Biol, 5(7), e184 EP -.
Abstract: <p>Experimental evidence reveals that chimpanzees will help other unrelated humans and conspecifics without a reward, showing that they share crucial aspects of altruism with humans.</p>
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MacLean, E., Matthews, L., Hare, B., Nunn, C., Anderson, R., Aureli, F., et al. (2012). How does cognition evolve? Phylogenetic comparative psychology. Anim. Cogn., 15(2), 223–238.
Abstract: Now more than ever animal studies have the potential to test hypotheses regarding how cognition evolves. Comparative psychologists have developed new techniques to probe the cognitive mechanisms underlying animal behavior, and they have become increasingly skillful at adapting methodologies to test multiple species. Meanwhile, evolutionary biologists have generated quantitative approaches to investigate the phylogenetic distribution and function of phenotypic traits, including cognition. In particular, phylogenetic methods can quantitatively (1) test whether specific cognitive abilities are correlated with life history (e.g., lifespan), morphology (e.g., brain size), or socio-ecological variables (e.g., social system), (2) measure how strongly phylogenetic relatedness predicts the distribution of cognitive skills across species, and (3) estimate the ancestral state of a given cognitive trait using measures of cognitive performance from extant species. Phylogenetic methods can also be used to guide the selection of species comparisons that offer the strongest tests of a priori predictions of cognitive evolutionary hypotheses (i.e., phylogenetic targeting). Here, we explain how an integration of comparative psychology and evolutionary biology will answer a host of questions regarding the phylogenetic distribution and history of cognitive traits, as well as the evolutionary processes that drove their evolution.
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Itakura, S., Agnetta, B., Hare, B., & Tomasello, M. (2001). Chimpanzee Use of Human and Conspecific Social Cues to Locate Hidden Food. Dev Sci, 2(2), 448–456.
Abstract: 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.
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Herrmann, E., Call, J., Hernandez-Lloreda, M. V., Hare, B., & Tomasello, M. (2007). online material. Science, 317(5843), 1360–1366.
Abstract: Humans have many cognitive skills not possessed by their nearest primate relatives. The cultural intelligence hypothesis argues that this is mainly due to a species-specific set of social-cognitive skills, emerging early in ontogeny, for participating and exchanging knowledge in cultural groups. We tested this hypothesis by giving a comprehensive battery of cognitive tests to large numbers of two of humans' closest primate relatives, chimpanzees and orangutans, as well as to 2.5-year-old human children before literacy and schooling. Supporting the cultural intelligence hypothesis and contradicting the hypothesis that humans simply have more “general intelligence,” we found that the children and chimpanzees had very similar cognitive skills for dealing with the physical world but that the children had more sophisticated cognitive skills than either of the ape species for dealing with the social world.
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Herrmann, E., Call, J., Hernandez-Lloreda, M. V., Hare, B., & Tomasello, M. (2007). Humans Have Evolved Specialized Skills of Social Cognition: The Cultural Intelligence Hypothesis. Science, 317(5843), 1360–1366.
Abstract: Humans have many cognitive skills not possessed by their nearest primate relatives. The cultural intelligence hypothesis argues that this is mainly due to a species-specific set of social-cognitive skills, emerging early in ontogeny, for participating and exchanging knowledge in cultural groups. We tested this hypothesis by giving a comprehensive battery of cognitive tests to large numbers of two of humans' closest primate relatives, chimpanzees and orangutans, as well as to 2.5-year-old human children before literacy and schooling. Supporting the cultural intelligence hypothesis and contradicting the hypothesis that humans simply have more “general intelligence,” we found that the children and chimpanzees had very similar cognitive skills for dealing with the physical world but that the children had more sophisticated cognitive skills than either of the ape species for dealing with the social world.
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Call, J., Hare, B. A., & Tomasello, M. (1998). Chimpanzee gaze following in an object-choice task. Anim. Cogn., 1(2), 89–99.
Abstract: 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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Hare, B. (2001). Can competitive paradigms increase the validity of experiments on primate social cognition? Anim. Cogn., 4(3), 269–280.
Abstract: 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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Tomasello, M., Hare, B., & Fogleman, T. (2001). The ontogeny of gaze following in chimpanzees, Pan troglodytes, and rhesus macaques, Macaca mulatta. Anim. Behav., 61(2), 335–343.
Abstract: 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., Brown, M., Williamson, C., & Tomasello, M. (2002). The domestication of social cognition in dogs. Science, 298(5598), 1634–1636.
Abstract: Dogs are more skillful than great apes at a number of tasks in which they must read human communicative signals indicating the location of hidden food. In this study, we found that wolves who were raised by humans do not show these same skills, whereas domestic dog puppies only a few weeks old, even those that have had little human contact, do show these skills. These findings suggest that during the process of domestication, dogs have been selected for a set of social-cognitive abilities that enable them to communicate with humans in unique ways.
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