Mine and Thine: The Territorial Foundations of Human Property

Research shows that many animal species have morphological and cognitive adaptations for fighting with others to gain resources, but it remains unclear how humans make fighting decisions. Non-human animals often adaptively calibrate fighting behavior to ecological variables such as resource quantity and whether the resource is distributed uniformly or clustered in patches. Also, many species use strategies to reduce fighting costs such as resolving disputes based on power asymmetries or conventions. Here we show that humans apply an ownership convention in response to the problem of severe fighting. We designed a virtual environment where ten participants, acting as avatars, could forage and fight for electronic food items (convertible to cash). In the patchy condition, we observed an ownership convention—the avatar who arrives first is more likely to win—but in the uniform condition, where severe fighting is rare, the ownership convention is absent.

The psychology of coordination and common knowledge.

Research on human cooperation has concentrated on the puzzle of altruism, in which one actor incurs a cost to benefit another, and the psychology of reciprocity, which evolved to solve this problem. We examine the complementary puzzle of mutualism, in which actors can benefit each other simultaneously, and the psychology of coordination, which ensures such benefits. Coordination is facilitated by common knowledge—the recursive belief state in which A knows X, B knows X, A knows that B knows X, B knows that A knows X, ad infinitum. We test whether people are sensitive to common knowledge when deciding whether to engage in risky coordination. Participants decided between working alone for a certain profit and working together for a potentially higher profit that they would receive only if their partner made the same choice. Results showed that more participants attempted risky coordination when they and their prospective partner had common knowledge of the payoffs (broadcasted over a loudspeaker) than when they had only shared knowledge (conveyed to both by a messenger) or primary knowledge (revealed to each partner separately). These results confirm the hypothesis that people represent common knowledge as a distinct cognitive category that licenses them to coordinate with others for mutual gain. We discuss how this hypothesis can provide a unified explanation for diverse phenomena in human social life, including recursive mentalizing, performative speech acts, public assemblies and protests, and self-conscious emotional expressions.Psycholog

Replication Data for: Alliance formation in a side-taking experiment

We investigate in an economic experiment how people choose sides in disputes. In an eight-player side-taking game, two disputants at a time fight over an indivisible resource and other group members choose sides. The player with more supporters wins the resource, which is worth real money. Conflicts occur spontaneously between any two individuals in the group. Players choose sides by ranking their loyalties to everyone else in the group and they automatically support the disputant they ranked higher. We manipulate participants’ information about other players’ loyalties and also their ability to communicate with public chat messages. We find that participants spontaneously and quickly formed alliances, and more information about loyalties caused more alliance-building. Without communication, we observe little evidence of bandwagon or egalitarian strategies, but with communication, some groups invented rank rotation schemes to equalize payoffs while choosing the same side to avoid fighting costs

Investigations into the problems of moral cognition

Evolutionary theorists since Darwin have viewed morality as a system designed for altruism. However, the experimentally demonstrated properties of moral cognition show that morality is not well engineered to deliver benefits to family, friends, or groups. Instead, it appears that human morality is underlain by a distinct cognitive system that is separate from systems responsible for human altruism. Here I suggest that a careful dissection of moral cognition will require attention to the strategic interactions among perpetrators, victims, and condemners, because these interactions ultimately determine the functionality of moral systems. In particular, I claim that actor conscience must be distinguished from third-party condemnation because actors and third parties confront different problems. My analysis indicates that, in contrast to previous accounts, morality is engineered around third-party condemnation and that conscience is likely designed to avoid third-party sanctions. Focusing on third-party condemnation highlights three evolutionary mysteries: third-party judgment, moralistic punishment, and moral impartiality. I report the results of a series of investigations into these problems of moral cognition. The reported investigations concern alliance dynamics in human friendship, the nature of moral victim representations, the scope of inaction effects in moral reasoning, transparency effects on moral judgment, and audience effects on moralistic punishment. The results of these experiments broadly indicate that moral cognition is more complex and strategically sophisticated than supposed by previous theories. These investigations initiate a wide-ranging research program aimed at recovering the functional logic of moral cognition

forthcoming. Adaptationist punishment in humans

Abstract Immanuel Kant, Adam Smith, Charles Darwin, George Williams, and Stephen J. Gould, among others, have pointed out that observing that a certain behavior causes a certain effect does not itself license the inference that the effect was the result of intent or design to bring about that effect. Compliance with duty might not reflect the action of conscience, gains in trade might not be due to the benevolence of traders, and fox paws might not be designed to make tracks in snow. Similarly, when person A inflicts costs on person B and, in so doing, generates benefits to C, D, and E (or the group to which A through E belong, in aggregate), the inference that A's imposition of costs on B is by virtue of intent or design to bring about these welfare gains is not logically licensed. In short, labeling punishment "altruistic" because it has the effect of benefitting some individuals is inconsistent with key ideas in philosophy, economics, and biology. Understanding the ultimate cause and proximate design of the mechanisms that cause people to punish is likely to be important for understanding how punishment can help solve collective action problems

Audience Effects on Moralistic Punishment

Punishment has been proposed as being central to two distinctively human phenomena: cooperation in groups and morality. Here we investigate moralistic punishment, a behavior designed to inflict costs on another individual in response to a perceived moral violation. There is currently no consensus on which evolutionary model best accounts for this phenomenon in humans. Models that turn on individuals’ cultivating reputations as moralistic punishers clearly predict that psychological systems should be designed to increase punishment in response to information that one’s decisions to punish will be known by others. We report two experiments in which we induce participants to commit moral violations and then present third parties with the opportunity to pay to punish wrongdoers. Varying conditions of anonymity, we find that the presence of an audience—even if only the experimenter— causes an increase in moralistic punishment