Leda Cosmides

Leda Cosmides
University of California, Santa Barbara | UCSB · Department of Psychological and Brain Sciences

Doctor of Philosophy

About

158
Publications
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32,084
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Publications

Publications (158)
Article
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Evolutionary models of dyadic cooperation demonstrate that selection favors different strategies for reciprocity depending on opportunities to choose alternative partners. We propose that selection has favored mechanisms that estimate the extent to which others can switch partners and calibrate motivations to reciprocate and punish accordingly. The...
Preprint
Evolutionary models of dyadic cooperation demonstrate that selection favors different strategies for reciprocity depending on opportunities to choose alternative partners. We propose that selection has favored mechanisms that estimate the extent to which others can switch partners and calibrate motivations to reciprocate and punish accordingly. The...
Article
Full-text available
Political collective action requires assembling and motivating supporters. Many theories view emotions as functional tools for managing relationships, including within groups. We study what leads citizens to use the emotions anger and gratitude as social pressure. Specifically, we test what determines the use of these emotions to prevent potential...
Chapter
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The prospect that centuries of religious, intellectual, and cultural reference points will melt into an unrecognizable new landscape of scientific knowledge understandably provokes unease, visceral resistance, and even alarm in those who sense the magnitude of the coming changes. These feelings are even sharper for evolutionary psychologists, becau...
Preprint
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Natural selection produces cognitive systems that are well designed for solving ancestral adaptive problems. For a group-living species like our own, this principle implies that interacting with others will be regulated by sophisticated cognitive systems. Here we explain how evolutionary game theory is used to identify ancestral problems of social...
Article
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Human foragers are obligately group-living, and their high dependence on mutual aid is believed to have characterized our species' social evolution. It was therefore a central adaptive problem for our ancestors to avoid damaging the willingness of other group members to render them assistance. Cognitively, this requires a predictive map of the degr...
Article
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Becoming valuable to fellow group members so that one would attract assistance in times of need is a major adaptive problem. To solve it, the individual needs a predictive map of the degree to which others value different acts so that, in choosing how to act, the payoff arising from others' valuation of a potential action (e.g., showing bandmates t...
Article
Why do humans help others? Many theories focus on dimensions like kinship or reciprocity. On their surface, these theories seem unable to explain help directed at fleeting strangers. In response to this puzzle, researchers have proposed that the mind has ecologically rational systems for providing aid. These systems respond to cues that predicted a...
Article
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What is the trigger of shame? The information threat theory holds that shame is an evolved adaptation that is designed to limit the likelihood and costs of others forming negative beliefs about the self. By contrast, attributional theories posit that concerns over others’ evaluations are irrelevant to shame. Instead, shame is triggered when a perso...
Preprint
Full-text available
Natural selection produces cognitive systems that are well-designed for solving ancestral adaptive problems (consider vision). This principle implies that interacting with others will be regulated by sophisticated cognitive systems in a group-living species, like our own. Here we explain how evolutionary game theory is used to identify ancestral pr...
Article
According to the recalibrational theory of anger, anger is a computationally complex cognitive system that evolved to bargain for better treatment. Anger coordinates facial expressions, vocal changes, verbal arguments, the withholding of benefits, the deployment of aggression, and a suite of other cognitive and physiological variables in the servic...
Article
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Why do people support economic redistribution? Hypotheses include inequity aversion, a moral sense that inequality is intrinsically unfair, and cultural explanations such as exposure to and assimilation of culturally transmitted ideologies. However, humans have been interacting with worse-off and better-off individuals over evolutionary time, and o...
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Pride occurs in every known culture, appears early in development, is reliably triggered by achievements and formidability, and causes a characteristic display that is recognized everywhere. Here, we evaluate the theory that pride evolved to guide decisions relevant to pursuing actions that enhance valuation and respect for a person in the minds of...
Article
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Theories advanced to explain conditional reasoning range from those that invoke inference systems that evolved for specific domains (such as social exchange, precautions, or deontic regulations) to relevance theory, a relatively domain-general account that invokes conversational pragmatics. The present research utilized a novel extension of repetit...
Article
There is substantial evidence from archaeology, anthropology, primatology, and psychology indicating that humans have a long evolutionary history of war. Natural selection, therefore, should have designed mental adaptations for making decisions about war. These adaptations evolved in past environments, and so they may respond to variables that were...
Article
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We test the theory that shame evolved as a defense against being devalued by others. By hypothesis, shame is a neurocomputational program tailored by selection to orchestrate cognition, motivation, physiology, and behavior in the service of: (i) deterring the individual from making choices where the prospective costs of devaluation exceed the benef...
Article
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Third-party intervention, such as when a crowd stops a mugger, is common. Yet it seems irrational because it has real costs but may provide no personal benefits. In a laboratory analogue, the third-party-punishment game, third parties ("punishers") will often spend real money to anonymously punish bad behavior directed at other people. A common exp...
Article
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The properties of individual carbon atoms allow them to chain into complex molecules of immense length. They are not limited to structures involving only a few atoms. The design features of our evolved neural adaptations appear similarly extensible. Individuals with forager brains can link themselves together into unprecedentedly large cooperative...
Chapter
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The human brain is the most highly organized system yet identified, and natural selection is the only physical process capable of pushing the designs of species uphill against entropy.Consequently, all functional mechanisms present in our species' neural architecture were constructed by selection acting on our ancestors.The design features of our p...
Chapter
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Social exchange—cooperation for mutual benefit—is rare in the animal kingdom. Yet it is as characteristic of human beings as language and tool use. We present evidence that our brains contain cognitive adaptations for reasoning about social exchange, which include a subroutine designed for detecting cheaters. The programs that generate cooperative...
Chapter
The long-term scientific goal toward which evolutionary psychologists are working is the mapping of the universal human nature. Evolutionary psychology provokes so much reflexive opposition because the stakes for many social scientists, behavioral scientists, and humanists are so high. If evolutionary psychology turns out to be well-founded, then t...
Chapter
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For 25 years, the authors have been investigating the hypothesis that the enduring presence of social exchange interactions among our ancestors has selected for cognitive mechanisms that are specialized for reasoning about social exchange. This chapter discusses some of the high points of this 25-year research program. It argues that social exchang...
Article
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Humans everywhere cooperate in groups to achieve benefits not attainable by individuals. Individual effort is often not automatically tied to a proportionate share of group benefits. This decoupling allows for free-riding, a strategy that (absent countermeasures) outcompetes cooperation. Empirically and formally, punishment potentially solves the e...
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Animals typically deploy their morphology during conflict to enhance competitors' assessments of their fighting ability (e.g. bared fangs, piloerection, dewlap inflation). Recent research has shown that humans assess others' fighting ability by monitoring cues of strength, and that the face itself contains such cues. We propose that the muscle move...
Article
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Prior to, or concurrent with, the encoding of concepts into speech, the individual faces decisions about whether, what, when, how, and with whom to communicate. Compared to the existing wealth of linguistic knowledge however, we know little of the mechanisms that govern the delivery and accrual of information. Here we focus on a fundamental issue o...
Article
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Some people are especially physically adept, others carry dangerous pathogens, some have valuable and rare knowledge, and still others cheat or deceive those around them. Because of these differences, and the costs and benefits they pose, natural selection has crafted mechanisms of partner choice that are selective: some people are chosen as social...
Article
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Humans in all societies form and participate in cooperative alliances. To successfully navigate an alliance-laced world, the human mind needs to detect new coalitions and alliances as they emerge, and predict which of many potential alliance categories are currently organizing an interaction. We propose that evolution has equipped the mind with cog...
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People regularly free ride on collective benefits, consuming them without contributing to their creation. In response, free riders are often moralized, becoming targets of negative moral judgments, anger, ostracism, or punishment. Moralization can change free riders' behavior (e.g., encouraging them to contribute or discouraging them from taking fu...
Article
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Over human evolutionary history, upper-body strength has been a major component of fighting ability. Evolutionary models of animal conflict predict that actors with greater fighting ability will more actively attempt to acquire or defend resources than less formidable contestants will. Here, we applied these models to political decision making abou...
Article
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Humans are often generous, even towards strangers encountered by chance and even in the absence of any explicit information suggesting they will meet again. Because game theoretic analyses typically conclude that a psychology designed for direct reciprocity should defect in such situations, many have concluded that alternative explanations for huma...
Article
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Evolutionary psychology is the second wave of the cognitive revolution. The first wave focused on computational processes that generate knowledge about the world: perception, attention, categorization, reasoning, learning, and memory. The second wave views the brain as composed of evolved computational systems, engineered by natural selection to us...
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We propose that intuitions about modern mass-level criminal justice emerge from evolved mechanisms designed to operate in ancestral small-scale societies. By hypothesis, individuals confronted with a crime compute two distinct psychological magnitudes: one that reflects the crime's seriousness and another that reflects the criminal's long-term valu...
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Why did punishment and the use of reputation evolve in humans? According to one family of theories, they evolved to support the maintenance of cooperative group norms; according to another, they evolved to enhance personal gains from cooperation. Current behavioral data are consistent with both hypotheses (and both selection pressures could have sh...
Data
Data Coding Scheme and Results. (DOCX)
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Evidence suggests that our foraging ancestors engaged in the small-scale equivalent of social insurance as an essential tool of survival and evolved a sophisticated psychology of social exchange (involving the social emotions of compassion and anger) to regulate mutual assistance. Here, we hypothesize that political support for modern welfare polic...
Article
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People vary in how easily they feel ashamed, that is, in their shame proneness. According to the information threat theory of shame, variation in shame proneness should, in part, be regulated by features of a person's social ecology. On this view, shame is an emotion program that evolved to mitigate the likelihood or costs of reputation-damaging in...
Article
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For collective action to evolve and be maintained by selection, the mind must be equipped with mechanisms designed to identify free riders--individuals who do not contribute to a collective project but still benefit from it. Once identified, free riders must be either punished or excluded from future collective actions. But what criteria does the m...
Article
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We thank McNally and Tanner (1) for their considered critique of our article (2). Our article addressed the puzzle of why humans, in one-shot interactions, often choose to incur costs to allocate benefits to others, with no possibility of recouping these losses (i.e., “irrational” generosity) (2). This empirical pattern challenges standard models o...
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Are humans too generous? The discovery that subjects choose to incur costs to allocate benefits to others in anonymous, one-shot economic games has posed an unsolved challenge to models of economic and evolutionary rationality. Using agent-based simulations, we show that such generosity is the necessary byproduct of selection on decision systems fo...
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Arising from M. A. Nowak, C. E. Tarnita & E. O. Wilson 466, 1057-1062 (2010); Nowak et al. reply. Nowak et al. argue that inclusive fitness theory has been of little value in explaining the natural world, and that it has led to negligible progress in explaining the evolution of eusociality. However, we believe that their arguments are based upon a...
Article
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Recent research has shown that humans, like many other animals, have a specialization for assessing fighting ability from visual cues. Because it is probable that the voice contains cues of strength and formidability that are not available visually, we predicted that selection has also equipped humans with the ability to estimate physical strength...
Article
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The evolution of cooperation between unrelated individuals has long been a puzzle in evolutionary biology. Formal models show that reciprocal altruism is approximately as stable as kin-based altruism when cooperators can assort. Why, then, is reciprocal altruism so rare? We suggest that the key lies in the difficulty of assortment based on underlyi...
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J. Henrich et al. 's Research Article (“Markets, religion, community size, and the evolution of fairness and punishment,” 19 March, p. [1480][1]) is a valuable addition to the growing literature testing behavioral hypotheses through careful cross-cultural measurement. However, the data they
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Blank-slate theories of human intelligence propose that reasoning is carried out by general-purpose operations applied uniformly across contents. An evolutionary approach implies a radically different model of human intelligence. The task demands of different adaptive problems select for functionally specialized problem-solving strategies, unleashi...
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War, Coalitions, and the HUnlan Condition War is older than the human species. It is found in every region of the world, among all the branches of humankind. It is found throughout human history, deeply and densely woven into its causal tapestry. It is found in all eras, and in earlier periods no less than later. There is no evidence of it having o...
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Eleven predictions derived from the recalibrational theory of anger were tested. This theory proposes that anger is produced by a neurocognitive program engineered by natural selection to use bargaining tactics to resolve conflicts of interest in favor of the angry individual. The program is designed to orchestrate two interpersonal negotiating tac...
Article
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Over the past two decades, an abundance of evidence has shown that individuals typically rely on semantic summary knowledge when making trait judgments about self and others (for reviews, see Klein, 2004; Klein, Robertson, Gangi, & Loftus, 2008). But why form trait summaries if one can consult the original episodes on which the summary was based? C...
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Selection in species with aggressive social interactions favours the evolution of cognitive mechanisms for assessing physical formidability (fighting ability or resource-holding potential). The ability to accurately assess formidability in conspecifics has been documented in a number of non-human species, but has not been demonstrated in humans. He...
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Relative social status strongly regulates human behavior, yet this factor has been largely ignored in research on risky decision-making. Humans, like other animals, incur risks as they compete to defend or improve their standing in a social group. Among men, access to culturally important resources is a locus of intrasexual competition and a determ...
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Visual attention mechanisms are known to select information to process based on current goals, personal relevance, and lower-level features. Here we present evidence that human visual attention also includes a high-level category-specialized system that monitors animals in an ongoing manner. Exposed to alternations between complex natural scenes an...
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Evolved mechanisms for assessing genetic relatedness have been found in many species, but their existence in humans has been a matter of controversy. Here we report three converging lines of evidence, drawn from siblings, that support the hypothesis that kin detection mechanisms exist in humans. These operate by computing, for each familiar individ...
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For two decades, the integrated causal model of evolutionary psychology (EP) has constituted an interdisciplinary nucleus around which a single unified theoretical and empirical behavioral science has been crystallizing – while progressively resolving problems (such as defective logical and statistical reasoning) that bedevil Gintis's beliefs, pref...