Peter DeScioli

Disgust: Evolved Function and Structure

Interest in and research on disgust has surged over the past few decades. The field, however, still lacks a coherent theoretical framework for understanding the evolved function or functions of disgust. Here we present such a framework, emphasizing 2 levels of analysis: that of evolved function and that of information processing. Although there is widespread agreement that disgust evolved to motivate the avoidance of contact with disease-causing organisms, there is no consensus about the functions disgust serves when evoked by acts unrelated to pathogen avoidance. Here we suggest that in addition to motivating pathogen avoidance, disgust evolved to regulate decisions in the domains of mate choice and morality. For each proposed evolved function, we posit distinct information processing systems that integrate function-relevant information and account for the trade-offs required of each disgust system. By refocusing the discussion of disgust on computational mechanisms, we recast prior theorizing on disgust into a framework that can generate new lines of empirical and theoretical inquiry.

Mysteries of morality.

Evolutionary theories of morality, beginning with Darwin, have focused on explanations for altruism. More generally, these accounts have concentrated on conscience (self-regulatory mechanisms) to the neglect of condemnation (mechanisms for punishing others). As a result, few theoretical tools are available for understanding the rapidly accumulating data surrounding third-party judgment and punishment. Here we consider the strategic interactions among actors, victims, and third-parties to help illuminate condemnation. We argue that basic differences between the adaptive problems faced by actors and third-parties indicate that actor conscience and third-party condemnation are likely performed by different cognitive mechanisms. Further, we argue that current theories of conscience do not easily explain its experimentally demonstrated insensitivity to consequences. However, these results might be explicable if conscience functions, in part, as a defense system for avoiding third-party punishment. If conscience serves defensive functions, then its computational structure should be closely tailored to the details of condemnation mechanisms. This possibility underscores the need for a better understanding of condemnation, which is important not only in itself but also for explaining the nature of conscience. We outline three evolutionary mysteries of condemnation that require further attention: third-party judgment, moralistic punishment, and moral impartiality.

The Omission Strategy

People are more willing to bring about morally objectionable outcomes by omission than by commission. Similarly, people condemn others less harshly when a moral offense occurs by omission rather than by commission, even when intentions are controlled. We propose that these two phenomena are related, and that the reduced moral condemnation of omissions causes people to choose omissions in their own behavior to avoid punishment. We report two experiments using an economic game in which one participant (the taker) could take money from another participant (the owner) either by omission or by commission. We manipulated whether or not a third party had the opportunity to punish the taker by reducing the taker’s payment. Our results indicated that the frequency of omission increases when punishment is possible. We conclude that people choose omissions to avoid condemnation and that the omission effect is best understood not as a bias, but as a strategy.

Best Friends Alliances, Friend Ranking, and the MySpace Social Network

Like many topics of psychological research, the explanation for friendship is at once intuitive and difficult to address empirically. These difficulties worsen when one seeks, as we do, to go beyond “obvious” explanations (“humans are social creatures”) to ask deeper questions, such as “What is the evolved function of human friendship?” In recent years, however, a new window into human behavior has opened as a growing fraction of people’s social activity has moved online, leaving a wealth of digital traces behind. One example is a feature of the MySpace social network that allows millions of users to rank their “Top Friends.” In this study, we collected over 10 million people’s friendship decisions from MySpace to test predictions made by hypotheses about human friendship. We found particular support for the alliance hypothesis, which holds that human friendship is caused by cognitive systems that function to create alliances for potential disputes. Because an ally’s support can be undermined by a stronger outside relationship, the alliance model predicts that people will prefer partners who rank them above other friends. Consistent with the alliance model, we found that an individual’s choice of best friend in MySpace is strongly predicted by how partners rank that individual.

Indelible Victims and Persistent Punishers in Moral Cognition

Pinocchio is alone on a lifeless planet. Is it possible for Pinocchio to do something morally wrong? If he shouts falsehoods into empty space, will his nose grow longer? Will the moral lessons he learned from Jiminy Cricket be of any use? Pinocchio certainly can take actions prohibited by moral rules. He can commit suicide, eat pork, take drugs, worship pagan gods, speak false oaths, desecrate graves, or cannibalize the dead bodies of other marionettes. Are these actions morally wrong, even when there are no other living individuals and no victims? Gray, Young, and Waytz (this issue) argue that victims are essential elements of moral judgment, implying that Pinocchio is incapable of wrongdoing. The authors write that “despite the variety of moral transgressions, there is a cognitive template of morality—the moral dyad—which not only integrates across various moral transgressions, but also serves as a working model for understanding the moral world” (pp. 102–103). According to this hypothesis, people have a cognitive template for moral interactions that includes both an agent and a patient. Hence, if there are no patients, then there is no wrongdoing. If it is true that victims are fundamental to moral judgment, then there are two ways that people could respond to Pinocchio’s predicament. First, they could say that it is impossible for Pinocchio to commit wrongdoing in isolation from other individuals. We refer to this idea as a “victim requirement” for wrongdoing. Second, people could deny the premise of the thought experiment by representing victims for the prohibited actions, even when actual victims are unavailable. We refer to this idea as “victim completion.” Gray et al. (this issue) favor the victim requirement view in their argument that a victim’s harm and suffering are required for moral judgment. They offer a bottom-up account in which lower level judgments about harm are inputs to higher level moral judgments. They argue that “mind perception is crucial for switching on the ‘moral faculty’” (p. 115), implying that moral judgment is not activated until after a victim’s suffering mind has been perceived. This idea is further clarified in their argument that “intent, cause, personal force, and valuation may be combined into a moral judgment, but mind perception precedes these computations” (p. 115). If a victim’s suffering has to be perceived first, as the authors argue, then solo agents like Pinocchio will be incapable of wrongdoing. However, there is another way that victims could be central to moral judgments. People could show victim completion—the perception of a victim of a moral offense even when an actual victim is absent or unclear. We suggest a top-down account of moral judgment in which the moral faculty can be switched on by a variety of factors that compose cognitive models of moral events. These models could include suffering victims as one element while also including other elements such as menacing perpetrators, righteous punishers, or specific violating actions. Evidence for any one of these elements could potentially activate moral computations. Once activated, moral cognition could seek to fill the remaining slots of the cognitive template with the best available alternatives. These mechanisms could cause people to perceive victims even if little evidence exists for genuine victims or suffering. These models can be empirically tested by examining the association between wrongness judgments and victim perceptions, and further by looking at the specific victims people perceive and the evidence they use to identify these victims. If victims are not core elements of moral judgment, then people will readily judge some actions to be morally wrong while perceiving no victim. In contrast, if victims are fundamental, then wrongness judgments will strongly predict victim perceptions. In this case, there are two possibilities—a victim requirement or victim completion—which can be empirically distinguished by examining the specific victims that people nominate. The required victim model predicts that people will perceive a particular victim only when there is clear evidence for the victim’s suffering. The victim completion model, in contrast, predicts that people will often perceive “unverifiable victims” based on little or no evidence of their suffering. Here we report a study of victim completion effects. We present the results of the moral victim study, address different potential interpretations, and discuss the evolved functions of people’s moral models.

The Commitment Function of Angry Facial Expressions

What function do facial expressions have? We tested the hypothesis that some expressions serve as honest signals of subjective commitments—in particular, that angry faces increase the effectiveness of threats. In an ultimatum game, proposers decided how much money to offer a responder while seeing a film clip depicting an angry or a neutral facial expression, together with a written threat that was either inherently credible (a 50-50 split) or less credible (a demand for 70% of the money). Proposers offered greater amounts in response to the less credible threat when it was accompanied by an angry expression than when it was accompanied by a neutral expression, but were unaffected by the expression when dealing with the credible threat. This finding supports the hypothesis that angry expressions are honest signals that enhance the credibility of threats.

Omissions and Byproducts across Moral Domains

Research indicates that moral violations are judged less wrong when the violation results from omission as opposed to commission, and when the violation is a byproduct as opposed to a means to an end. Previous work examined these effects mainly for violent offenses such as killing. Here we investigate the generality of these effects across a range of moral violations including sexuality, food, property, and group loyalty. In Experiment 1, we observed omission effects in wrongness ratings for all of the twelve offenses investigated. In Experiments 2 and 3, we observed byproduct effects in wrongness ratings for seven and eight offenses (out of twelve), respectively, and we observed byproduct effects in forced-choice responses for all twelve offenses. Our results address an ongoing debate about whether different cognitive systems compute moral wrongness for different types of behaviors (surrounding violence, sexuality, food, etc.), or, alternatively, a common cognitive architecture computes wrongness for a variety of behaviors.

Adaptationist Punishment in Humans

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. Copyright Springer Science+Business Media New York 2013

People's Judgments About Classic Property Law Cases

People’s judgments about property shape how they relate to other people with respect to resources. Property law cases can provide a valuable window into ownership judgments because disputants often use conflicting rules for ownership, offering opportunities to distinguish these basic rules. Here we report a series of ten studies investigating people’s judgments about classic property law cases dealing with found objects. The cases address a range of issues, including the relativity of ownership, finder versus landowner rights, object location, objects below- versus above-ground, mislaid versus lost objects, contracts between landowners and finders, and the distinction between public and private space. The results show nuanced patterns in ownership judgments that are not well-explained by previous psychological theories. Also, people’s judgments often conflict with court decisions and legal principles. These empirical patterns can be used to generate and test novel hypotheses about the intuitive logic of ownership.

The Communicative Function of Sad Facial Expressions

What are the communicative functions of sad facial expressions? Research shows that people feel sadness in response to losses but it’s unclear whether sad expressions function to communicate losses to others and if so, what makes these signals credible. Here we use economic games to test the hypothesis that sad expressions lend credibility to claims of loss. Participants play the role of either a proposer or recipient in a game with a fictional backstory and real monetary payoffs. The proposers view a (fictional) video of the recipient’s character displaying either a neutral or sad expression paired with a claim of loss. The proposer then decided how much money to give to the recipient. In three experiments, we test alternative theories by using situations in which the recipient’s losses were uncertain (Experiment 1), the recipient’s losses were certain (Experiment 2), or the recipient claims failed gains rather than losses (Experiment 3). Overall, we find that participants gave more money to recipients who displayed sad expressions compared to neutral expressions, but only under conditions of uncertain loss. This finding supports the hypothesis that sad expressions function to increase the credibility of claims of loss.