Researchers in judgment under uncertainty have argued that biases, fallacies, and framing effects explain much of the apparently nonfunctional variation in human decision-making. Recent work by evolutionary researchers shows, however, that many decisions that appear irrational by mathematical standards are ecologically rational—that is, produced by computational systems well-engineered for achieving adaptive performance on evolutionarily recurrent tasks (Wang, 1996a
; Cosmides & Tooby, 1996
; Rode, Cosmides, Hell, & Tooby, 1999
; Brase, Cosmides, & Tooby, 1998
; Gigerenzer & Selton, 2001
; Haselton & Nettle, 2006
). For example, ambiguity aversion is often thought to be a stable and irrational bias in human decision-making. Subsequent experiments have shown, however, that it is an easily reversible product of a powerful adaptive system designed for risky decision-making (Rode et al., 1999
). The design of this system is ecologically rational, conforming to a functional logic specified by the evolutionary theory of risk-sensitive foraging (Rode et al., 1999
Here we explore two additional possibilities involving risky decision-making. First, risky decision-making may not be a unitary phenomenon; it might fractionate into several more evolutionarily specialized sub-domains, each activating different evolved decision-making principles. For example, although resource acquisition can occur during foraging or status competition, status competition may activate an evolved system for making risky decisions about resources that is distinct from those activated by foraging and other contexts.
Second, if risky decision-making does fractionate along motivational lines (e.g., status relevant vs. status irrelevant), this may have implications for the evolution of motivation and cognition. Motivation is often treated simply as a system that plugs exogenous preferences (such as utilities) into uniform and domain-general cognitive procedures. We suggest, however, that a more satisfying account of decision-making can be achieved by hypothesizing that motivational and cognitive mechanisms co-evolved to operate in coordinated, domain-specific ways. On this account, a given motivational system is equipped with its own distinct and proprietary cognitive mechanisms, which are designed to interact with regulatory variables (e.g., representations of relative status) in ways that produce highly domain-specialized (and adaptively well-engineered) patterns of risky-decision making.
One virtue of taking an evolutionary approach is that, in many cases, there already exist powerful, precise theories of how functional systems ought to be designed. In this case, we believe that dominance theory, drawn from the evolutionary biology of animal conflict (Hammerstein & Parker, 1982
; Maynard Smith, 1974
; Maynard Smith & Price, 1973
), can be used to predict patterns in risky-decision making in conditions involving social competition. Indeed, many social species are known to have evolved motivational systems designed for successfully navigating dominance and status interactions (Archer, 1988
). These systems use information about relative status to regulate decisions to risk harm and loss in pursuit of resources—or status itself. Humans likewise evolved in social groups in which status and dominance relationships regulated access to resources. This fact leads to the expectation that humans have also evolved a motivational system designed to regulate willingness to take competitive risks in dominance-relevant contexts.
Researchers typically operationalize risky decision-making as a choice between two options that are equal in average expected payoff—one certain (win $20), the other risky (1/3 chance of winning $60, 2/3 chance of getting nothing). Evolutionarily, the question posed to the organism is not what choice yields the highest direct payoff, but what choice typically yielded the most fitness-promoting payoff. Often these converge. However, risky decisions that have implications for status and dominance entail social costs and benefits beyond the immediate resources lost or gained—ones which do not apply to risky decisions in pursuit of foraged plants, predator evasion, and other domains. Such analyses led us to propose that men’s minds are equipped with evolved domain-specific decision-making mechanisms designed to regulate competitive risks in response to cues of relative status. Herein we test for the existence of such mechanisms, using risky choice problems that have been classic research tools in the cognitive literature on judgment under uncertainty.
1.1 Resources and intrasexual competition in men
Computational systems designed to regulate intrasexual competition should exist in the brains of both men and women, but their designs should be sexually dimorphic. Across cultures, women prefer men with higher status and access to culturally-valued resources as mates (Buss, 1989
). In comparison, men’s mate preferences are relatively insensitive to variations in the status and resources of women (Buss, 1989
; Townsend, 1989
). Not surprisingly, then, status gained through access to culturally-valued resources plays a more important role in intrasexual competition among men than among women (Buss, 1992
). For example, male-male homicide rates increase with income inequality, suggesting that young men’s minds are designed to up-regulate motivations to take competitive risks in response to cues that their mating opportunities are limited by lack of resources (Daly, Wilson, & Vasdev, 2001
Based on these well-documented facts, we predicted that motivational systems designed to regulate competitive risk-taking in the service of achieving and maintaining status will be activated by situations involving resource acquisition in men, but not in women.
Preliminary evidence is consistent with this hypothesis. Men’s risky decision-making is influenced by whether others are watching, and possibly evaluating, their actions: when betting for real money, the presence of peers facilitates willingness to choose high risk/high gain gambles in young men, but not in young women (Daly & Wilson, 2001
). Our goal is to test whether men’s motivation for competitive risk-taking is regulated not just by the presence of observers, but also by their status relative to them.
To test for status-regulated features predicted to exist in a computational system shaped by selection pressures for male-male intrasexual competition, we conducted experiments in which subjects believed individuals of the same sex were observing and evaluating their actions, and varied the status of the subject relative to these (alleged) observers. We also varied whether the domain of risk was status-relevant (resources) or status-irrelevant (medical treatments). Prospect theory (Kahneman & Tversky, 1973
; Tversky & Kahneman, 1981
) and other approaches to risky-decision making found in the cognitive literature make no predictions about how sex, domain of risk, or status of observers regulate risk-taking. But two theories from behavioral ecology can be applied to make predictions about how, specifically, men’s risky choices about resources should be regulated by social status: risk-sensitive foraging theory and dominance theory.
1.2 Risk-Sensitive Foraging Theory
According to risk-sensitive foraging models (Stephens & Krebs, 1986
), an organism’s need level should regulate risky decision-making, in conjunction with the statistical parameters associated with each choice. If two foraging patches have the same mean caloric return, but differ in outcome variance, then the best choice depends on the organism’s state. When the forager needs more than the mean expected return to survive, the chances of meeting that need level are maximized by choosing the high variance (i.e., risky) patch. The low variance patch is the safer choice only when the forager’s survival needs are less than or equal to its mean return. Risk-sensitive foraging models have successfully predicted animal foraging (e.g., Real & Caraco, 1986
Moreover, this model appears to successfully predict human risky-decision making, even on complex tasks that exceed the capacity of subjects to make deliberative calculations (e.g., Rode et al., 1999
; Wang, 1996a
). These results imply that the human mind contains a nonconscious specialization that embodies these decision-making principles.
The logic of these models is general: Choosing risk is more likely to meet one’s aspiration level whenever mean expected outcomes fall below the minimum to which one aspires—whether one’s minimum aspiration is for a specified number of calories or a specified level of status. By positing an aspiration level for status, this approach can be applied to the current research. Social status is always relative: having a high or low level depends on the current comparison group. Thus, one might expect men to have a relatively constant aspiration for higher status relative to others. If men seek resources to gain higher relative status, this model predicts they will seek risk when their status is lower than or equal to the status of the men observing and evaluating their actions (because their status aspiration level has not yet been met) and avoid risk when their own status is higher (because their status aspiration level has already been satisfied). On this view, risky decisions are regulated by domain-general decision rules, and men and women differ only because the domain of resource acquisition fits the input conditions for potential status gains in men, but not in women.
1.3 Dominance Theory
According to dominance models, such as the asymmetric war of attrition (Hammerstein & Parker, 1982
), motivations to risk injury in pursuit of resources are jointly regulated by the relative value of a resource to both contestants and their relative ability to harm one another. When both contestants value a resource equally and one is clearly able to inflict more harm than the other in a fight, the less formidable individual is better off ceding the resource rather than risking injury in a fight he is sure to lose. This model predicts the evolution of low-cost displays through which the relative ability to inflict harm can be reliably assessed; in stable social groups, these assessments should lead to the emergence of dominance ranks (Barnard & Burk, 1979
; Clutton-Brock & Albon, 1979
If a stable dominance hierarchy has emerged, discrepancy in relative rank should regulate motivations to take risks to defend (or acquire) a resource. When ranks are clearly different (and both value the resource equally), the evolutionarily stable strategy is for lower ranking individuals to defer to the resource demands of higher ranking ones. Motivations for risk-taking should be low in both contestants because both benefit by this—lower ranked individuals do not incur major injuries fighting for resources they will fail to obtain, and higher ranked individuals obtain those resources without the costs of a contest (lost time, energy, and risk of injury).
Payoffs change, however, when contestants are of similar rank; challenges should increase, as well as motivation to defend against these challenges. As a result, motivations to take risks in pursuit of resources should be up-regulated when two individuals believe themselves to be equal in rank. Displays of cues relevant to assessing the contestants’ relative ability to inflict harm should escalate until both assess that an asymmetry in the ability to inflict harm exists, leading one of them to cede the resource. If this does not happen through displays, a fight may ensue to decide who gets the resource. Indeed, among humans, many male-male conflicts with escalating violence begin as disputes over “respect”, where a status challenge from an approximate equal cannot be ignored (Wilson, Daly, & Pound, 2002
Note that others benefit by being observers—indeed, many species have evolved the ability to infer a dominance hierarchy just by watching the contests of others, and individuals use these inferences to regulate their own decisions to risk a fight (e.g., Grosenick, Clement, & Fernald, 2007
). The presence of third-parties should magnify any effects of status on one’s risk-taking, because losing rank in a contest may lead observers of similar status, in addition to the current rival, to expect deference.
In these models, harm is conceptualized as risk of physical injury. To accommodate the human case, they can be generalized to include social harms, such as risk that a higher status individual will withdraw cooperation or access to other social benefits if the resource is not ceded. Generalized to include status ranks, dominance theory predicts that men’s motivation to take risks in pursuit of resources will be highest when two men of equal status want the same resource.
Men might not need to be in a direct competition for resources for this motivation to emerge: Given that observers may infer a man’s rank from his choices, believing that men of equal status will be watching and “evaluating” their choices may be sufficient to up-regulate men’s motivations to choose risk in pursuit of resources.
Note that dominance theory and risk-sensitive foraging theory both predict higher risk taking when men are facing status equals, but their predictions diverge for cases in which the status of the observers is different from that of the subject.
The theory and evidence above motivated our main hypotheses:
- Relative social status will regulate men’s choices in risky decision-making about resources.
- The joint presence of resource opportunities and status rivals will not elicit indiscriminate risk-taking in men. We compare two possibilities:
- If men’s risk-taking motivations result from an aspiration for higher status plugging into general risky decision-making mechanisms, as on the risk-sensitive foraging account, then relative status will up-regulate men’s willingness to take risks when their aspiration for higher status has not been met (i.e., when their relative status is lower than or equal to that of their potential evaluators).
- If, on the other hand, men’s risk-taking motivations result from a motivational system that was shaped by selection pressures specified by dominance theory, then relative status will up-regulate men’s willingness to take risks only when they face status equals (and not when they face potential evaluators of lower or higher status).
- The effects of status on men’s risk-taking should be domain-specific: Relative status will not regulate men’s risk-taking motivations in domains that were not relevant to intrasexual competition, such as medical decisions.
- The pattern described by i-iii will be specific to men: Relative status will not regulate women’s choices in risky decision-making about resources or medical decisions.