Browsing by Author "Hare, Brian"

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    A comparison of temperament in nonhuman apes and human infants.
    (Dev Sci, 2011-11) Herrmann, Esther; Hare, Brian; Cissewski, Julia; Tomasello, Michael
    The adaptive behavior of primates, including humans, is often mediated by temperament. Human behavior likely differs from that of other primates in part due to temperament. In the current study we compared the reaction of bonobos, chimpanzees, orangutans, and 2.5-year-old human infants to novel objects and people - as a measure of their shyness-boldness, a key temperamental trait. Human children at the age of 2.5 years avoided novelty of all kinds far more than the other ape species. This response was most similar to that seen in bonobos and least like that of chimpanzees and orangutans. This comparison represents a first step in characterizing the temperamental profiles of species in the hominoid clade, and these findings are consistent with the hypothesis that human temperament has evolved since our lineage diverged from the other apes in ways that likely have broad effects on behavior. These findings also provide new insights into how species differences in ecology may shape differences in temperament.
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    A fruit in the hand or two in the bush? Divergent risk preferences in chimpanzees and bonobos.
    (Biol Lett, 2008-06-23) Heilbronner, Sarah R; Rosati, Alexandra G; Stevens, Jeffrey R; Hare, Brian; Hauser, Marc D
    Human and non-human animals tend to avoid risky prospects. If such patterns of economic choice are adaptive, risk preferences should reflect the typical decision-making environments faced by organisms. However, this approach has not been widely used to examine the risk sensitivity in closely related species with different ecologies. Here, we experimentally examined risk-sensitive behaviour in chimpanzees (Pan troglodytes) and bonobos (Pan paniscus), closely related species whose distinct ecologies are thought to be the major selective force shaping their unique behavioural repertoires. Because chimpanzees exploit riskier food sources in the wild, we predicted that they would exhibit greater tolerance for risk in choices about food. Results confirmed this prediction: chimpanzees significantly preferred the risky option, whereas bonobos preferred the fixed option. These results provide a relatively rare example of risk-prone behaviour in the context of gains and show how ecological pressures can sculpt economic decision making.
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    Chimpanzees and bonobos distinguish between risk and ambiguity.
    (Biol Lett, 2011-02-23) Rosati, Alexandra G; Hare, Brian
    Although recent research has investigated animal decision-making under risk, little is known about how animals choose under conditions of ambiguity when they lack information about the available alternatives. Many models of choice behaviour assume that ambiguity does not impact decision-makers, but studies of humans suggest that people tend to be more averse to choosing ambiguous options than risky options with known probabilities. To illuminate the evolutionary roots of human economic behaviour, we examined whether our closest living relatives, chimpanzees (Pan troglodytes) and bonobos (Pan paniscus), share this bias against ambiguity. Apes chose between a certain option that reliably provided an intermediately preferred food type, and a variable option that could vary in the probability that it provided a highly preferred food type. To examine the impact of ambiguity on ape decision-making, we interspersed trials in which chimpanzees and bonobos had no knowledge about the probabilities. Both species avoided the ambiguous option compared with their choices for a risky option, indicating that ambiguity aversion is shared by humans, bonobos and chimpanzees.
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    Chimpanzees and bonobos exhibit divergent spatial memory development.
    (Dev Sci, 2012-11) Rosati, Alexandra G; Hare, Brian
    Spatial cognition and memory are critical cognitive skills underlying foraging behaviors for all primates. While the emergence of these skills has been the focus of much research on human children, little is known about ontogenetic patterns shaping spatial cognition in other species. Comparative developmental studies of nonhuman apes can illuminate which aspects of human spatial development are shared with other primates, versus which aspects are unique to our lineage. Here we present three studies examining spatial memory development in our closest living relatives, chimpanzees (Pan troglodytes) and bonobos (P. paniscus). We first compared memory in a naturalistic foraging task where apes had to recall the location of resources hidden in a large outdoor enclosure with a variety of landmarks (Studies 1 and 2). We then compared older apes using a matched memory choice paradigm (Study 3). We found that chimpanzees exhibited more accurate spatial memory than bonobos across contexts, supporting predictions from these species' different feeding ecologies. Furthermore, chimpanzees - but not bonobos - showed developmental improvements in spatial memory, indicating that bonobos exhibit cognitive paedomorphism (delays in developmental timing) in their spatial abilities relative to chimpanzees. Together, these results indicate that the development of spatial memory may differ even between closely related species. Moreover, changes in the spatial domain can emerge during nonhuman ape ontogeny, much like some changes seen in human children.
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    Differences in the cognitive skills of bonobos and chimpanzees.
    (PLoS One, 2010-08-27) Herrmann, Esther; Hare, Brian; Call, Josep; Tomasello, Michael
    While bonobos and chimpanzees are both genetically and behaviorally very similar, they also differ in significant ways. Bonobos are more cautious and socially tolerant while chimpanzees are more dependent on extractive foraging, which requires tools. The similarities suggest the two species should be cognitively similar while the behavioral differences predict where the two species should differ cognitively. We compared both species on a wide range of cognitive problems testing their understanding of the physical and social world. Bonobos were more skilled at solving tasks related to theory of mind or an understanding of social causality, while chimpanzees were more skilled at tasks requiring the use of tools and an understanding of physical causality. These species differences support the role of ecological and socio-ecological pressures in shaping cognitive skills over relatively short periods of evolutionary time.
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    Differences in the early cognitive development of children and great apes.
    (Dev Psychobiol, 2014-04) Wobber, Victoria; Herrmann, Esther; Hare, Brian; Wrangham, Richard; Tomasello, Michael
    There is very little research comparing great ape and human cognition developmentally. In the current studies we compared a cross-sectional sample of 2- to 4-year-old human children (n=48) with a large sample of chimpanzees and bonobos in the same age range (n=42, hereafter: apes) on a broad array of cognitive tasks. We then followed a group of juvenile apes (n=44) longitudinally over 3 years to track their cognitive development in greater detail. In skills of physical cognition (space, causality, quantities), children and apes performed comparably at 2 years of age, but by 4 years of age children were more advanced (whereas apes stayed at their 2-year-old performance levels). In skills of social cognition (communication, social learning, theory of mind), children out-performed apes already at 2 years, and increased this difference even more by 4 years. Patterns of development differed more between children and apes in the social domain than the physical domain, with support for these patterns present in both the cross-sectional and longitudinal ape data sets. These results indicate key differences in the pattern and pace of cognitive development between humans and other apes, particularly in the early emergence of specific social cognitive capacities in humans.
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    Direct and indirect reputation formation in nonhuman great apes (Pan paniscus, Pan troglodytes, Gorilla gorilla, Pongo pygmaeus) and human children (Homo sapiens).
    (J Comp Psychol, 2013-02) Herrmann, Esther; Keupp, Stefanie; Hare, Brian; Vaish, Amrisha; Tomasello, Michael
    Humans make decisions about when and with whom to cooperate based on their reputations. People either learn about others by direct interaction or by observing third-party interactions or gossip. An important question is whether other animal species, especially our closest living relatives, the nonhuman great apes, also form reputations of others. In Study 1, chimpanzees, bonobos, orangutans, and 2.5-year-old human children experienced a nice experimenter who tried to give food/toys to the subject and a mean experimenter who interrupted the food/toy giving. In studies 2 and 3, nonhuman great apes and human children could only passively observe a similar interaction, in which a nice experimenter and a mean experimenter interacted with a third party. Orangutans and 2.5-year-old human children preferred to approach the nice experimenter rather than the mean one after having directly experienced their respective behaviors. Orangutans, chimpanzees, and 2.5-year-old human children also took into account experimenter actions toward third parties in forming reputations. These studies show that the human ability to form direct and indirect reputation judgment is already present in young children and shared with at least some of the other great apes.
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    Looking past the model species: diversity in gaze-following skills across primates.
    (Curr Opin Neurobiol, 2009-02) Rosati, Alexandra G; Hare, Brian
    Primates must navigate complex social landscapes in their daily lives: gathering information from and about others, competing with others for food and mates, and cooperating to obtain rewards as well. Gaze-following often provides important clues as to what others see, know, or will do; using information about social attention is thus crucial for primates to be competent social actors. However, the cognitive bases of the gaze-following behaviors that primates exhibit appear to vary widely across species. The ultimate challenge of such analyses will therefore be to understand why such different cognitive mechanisms have evolved across species.
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    Motivating children's cooperation to conserve forests.
    (Conservation biology : the journal of the Society for Conservation Biology, 2022-04-18) Bowie, Aleah; Zhou, Wen; Tan, Jingzhi; White, Philip; Stoinski, Tara; Su, Yanjie; Hare, Brian
    Forests are essential common-pool resources. Understanding children's and adolescents' motivations for conservation is critical to improving conservation education. In 2 experiments, we investigated 1086 school-aged children and adolescents (6-16 years old) from China, the Democratic Republic of Congo, and the United States. testING participants in groups, we assessed their motivation for conservation based on collective-risk common-pool goods games in which they are threatened with losing their endowment unless the group donation exceeds a threshold needed to maintain the forest.eExtrinsic motivations, rather than intrinsic , tended to lead to successful cooperation to maintain a forest. Certainty of losing individual payoffs significantly boosted successful cooperative conservation efforts across cultures (success rates were 90.63 % and 74.19% in the 2 risk-extrinsic conditions and 43.75% in the control condition). In U.S. participants, 2 extrinsic incentives, priming discussions of the value of forests and delay of payoffs as punishment , also increased success of cooperative conservation (success rates were 97.22% and 76.92% in the 2 extrinsic-incentive conditions and 29.19% and 30.77% in the 2 control conditions). Conservation simulations, like those we used, may allow educators to encourage forest protection by leading groups to experience successful cooperation and the extrinsic incentives needed to motivate forest conservation. This article is protected by copyright. All rights reserved.
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    The Early Expression of Blatant Dehumanization in Children and Its Association with Outgroup Negativity.
    (Human nature (Hawthorne, N.Y.), 2022-06-06) Zhou, Wen; Hare, Brian
    Dehumanization is observed in adults across cultures and is thought to motivate human violence. The age of its first expression remains largely untested. This research demonstrates that diverse representations of humanness, including a novel one, readily elicit blatant dehumanization in adults (N = 482) and children (aged 5-12; N = 150). Dehumanizing responses in both age groups are associated with support for outgroup inferiority. Similar to the link previously observed in adults, dehumanization by children is associated with a willingness to punish outgroup transgressors. These findings suggest that exposure to cultural norms throughout adolescence and adulthood are not required for the development of outgroup dehumanization.
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    The evolutionary origins of human patience: temporal preferences in chimpanzees, bonobos, and human adults.
    (Curr Biol, 2007-10-09) Rosati, Alexandra G; Stevens, Jeffrey R; Hare, Brian; Hauser, Marc D
    To make adaptive choices, individuals must sometimes exhibit patience, forgoing immediate benefits to acquire more valuable future rewards [1-3]. Although humans account for future consequences when making temporal decisions [4], many animal species wait only a few seconds for delayed benefits [5-10]. Current research thus suggests a phylogenetic gap between patient humans and impulsive, present-oriented animals [9, 11], a distinction with implications for our understanding of economic decision making [12] and the origins of human cooperation [13]. On the basis of a series of experimental results, we reject this conclusion. First, bonobos (Pan paniscus) and chimpanzees (Pan troglodytes) exhibit a degree of patience not seen in other animals tested thus far. Second, humans are less willing to wait for food rewards than are chimpanzees. Third, humans are more willing to wait for monetary rewards than for food, and show the highest degree of patience only in response to decisions about money involving low opportunity costs. These findings suggest that core components of the capacity for future-oriented decisions evolved before the human lineage diverged from apes. Moreover, the different levels of patience that humans exhibit might be driven by fundamental differences in the mechanisms representing biological versus abstract rewards.
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    Use of "entertainment" chimpanzees in commercials distorts public perception regarding their conservation status.
    (PLoS One, 2011) Schroepfer, Kara K; Rosati, Alexandra G; Chartrand, Tanya; Hare, Brian
    Chimpanzees (Pan troglodytes) are often used in movies, commercials and print advertisements with the intention of eliciting a humorous response from audiences. The portrayal of chimpanzees in unnatural, human-like situations may have a negative effect on the public's understanding of their endangered status in the wild while making them appear as suitable pets. Alternatively, media content that elicits a positive emotional response toward chimpanzees may increase the public's commitment to chimpanzee conservation. To test these competing hypotheses, participants (n = 165) watched a series of commercials in an experiment framed as a marketing study. Imbedded within the same series of commercials was one of three chimpanzee videos. Participants either watched 1) a chimpanzee conservation commercial, 2) commercials containing "entertainment" chimpanzees or 3) control footage of the natural behavior of wild chimpanzees. Results from a post-viewing questionnaire reveal that participants who watched the conservation message understood that chimpanzees were endangered and unsuitable as pets at higher levels than those viewing the control footage. Meanwhile participants watching commercials with entertainment chimpanzees showed a decrease in understanding relative to those watching the control footage. In addition, when participants were given the opportunity to donate part of their earnings from the experiment to a conservation charity, donations were least frequent in the group watching commercials with entertainment chimpanzees. Control questions show that participants did not detect the purpose of the study. These results firmly support the hypothesis that use of entertainment chimpanzees in the popular media negatively distorts the public's perception and hinders chimpanzee conservation efforts.