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 and Tversky, 1973, Kahneman and Tversky, 1979, Tversky and 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 

The second perspective from behavioral ecology that may prove relevant to understanding the evolution of risky decision making in humans is dominance theory, which is based on analyses of animal conflicts and assessment strategies (Archer, 1988, Hammerstein and Parker, 1982, Maynard Smith, 1974, Maynard Smith and Price, 1973).

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 and Burk, 1979, Clutton-Brock and 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.

1.4. Predictions 

The theory and evidence above motivated our main hypotheses:

2.1. Method 

2.2. Manipulation checks and preliminary analyses 

2.3. Results and discussion 

The most important results are shown in Fig. 1 and Table 1. They are expressed as the percent of subjects choosing the risky option when the subject's status is lower (L), equal (E) or higher (H) than that of his or her (sham) evaluators. All p values are two tailed.

Fig. 1. Across both experiments, men chose the risky option on the resource loss decision problem more often when they were equal in social status than when they were relatively lower or higher in status.

For men, resources were (and are) an arena of intrasexual competition. When resources were at stake, did men's relative status affect how often they chose the risky option? Yes. As predicted, relative social status significantly affected how often men chose the risky option on the resource loss problem (subject's status: lower=43%, equal=79%, higher=29%; χ2(2, n=42)=7.43, p=.02, φ=.42).

Does the pattern of men's risky choices about resources fit the predictions of risk-sensitive foraging theory or dominance theory? Planned comparisons were conducted to test the predictions derived from risk-sensitive foraging theory and dominance theory (Table 1). These comparisons clearly supported dominance theory: men who thought they were being evaluated by status equals chose the high-risk/high-gain option for acquiring resources significantly more often than men who thought their own status was lower or higher than that of their evaluators (E>L: z=1.93, p=.05, φ=.37; E>H: z=2.65, p=.008, φ=.50). The proportions of men choosing the risky option in the lower and higher status conditions did not differ significantly from one another (L vs. H: z=0.79, p=.43, φ=.15).

We predicted that status effects in men would be domain specific, elicited by decisions relevant to male intrasexual competition. To control for domain and test for specificity, the same men also responded to a medical risk problem having nothing to do with intrasexual competition

When making decisions about a domain that is irrelevant to intrasexual competition, did men's relative status affect how often they chose the risky option? No. As predicted, relative status had no effect on how often men chose the risky option on the control problem, which involved medical treatments for preventing loss of life (L=64%, E=50%, H=57%; χ2(2, n=42)=0.58, p=.75, φ=.12).

Did women's relative status affect how often they chose risk? No. As predicted, social status did not significantly affect how often women chose the risky option on either problem (resource loss: L=35%, E=29%, H=33%; χ2(2, n=52)=0.14, p=.93, φ=.05; medical loss: L=53%, E=47%, H=39%; χ2(2, n=52)=0.70, p=.70, φ=.12).

These results underscore the importance of examining both the domain of risk and the social context in which risky decisions are made. When men believed other men would be observing and evaluating their decisions, their status relative to these “evaluators” regulated how willing they were to choose a high-risk/high-gain method of acquiring resources. As predicted, men's relative status affected their risky decision making only when the domain was relevant to male intrasexual competition: status effects were elicited by a chance to recover monetary resources, but not by decisions about risky medical treatments. The analysis of intrasexual competition in men that led to these predictions does not apply to women; as expected, women's relative social status did not affect their choices on either problem.

The effects of status in men support dominance theory. Faced with a resource acquisition problem, men chose the risky option more often when they thought their decisions would be seen and evaluated by other men of equal status. Men were more risk averse when their status differed — in either direction — from that of their alleged evaluators. This pattern is exactly what one would expect if men's risky decisions were being generated by a motivational system that evolved to regulate dominance interactions: activating motivations for competitive risk taking can make a difference when one's choices are being observed and evaluated by a competitor of equal status, but this strategy is not advantageous when discrepancies in status are large.

The results of this experiment indicate that the investigation of the effects of social status on risky decision making is a fruitful line of inquiry. Experiment 2 was conducted to replicate these status effects with a larger sample in a different population and to explore social status effects on other types of risky decision problems.

3.1. Method 

3.2. Manipulation checks and preliminary analyses 

3.3. Results and discussion 

The key results are shown in Fig. 1 and Table 1. As before, L, E and H (lower, equal, higher) refer to the subject's status relative to his or her sham evaluators.

3.3.2. Women's responses 

Were women's risky choices affected by their relative status? Yes. Although the resource loss problem elicited no status effects from women in Experiment 1 (φ=.05), the same problem did elicit status effects in Experiment 2 (L=45%, E=10%, H=50%: χ2(2, n=60)=8.35, p=.02, φ=.37; see Fig. 2).

Fig. 2. Across experiments, relative social status had no consistent effect on women's choices on the resource loss decision problem.

In Experiment 2, the risky option was chosen by significantly fewer women in the equal status condition than in the lower (E<L: z=−2.48, p=.01, φ=.39) or higher status conditions (E<H: z=−2.01, p=.006, φ=.44), and the proportions of women in the lower and higher status conditions did not differ significantly from one another (L vs. H; z=1.61, p=.75, φ=.05). This pattern does not fit dominance theory, risk-sensitive foraging theory or the pattern produced by women in response to the same problem in Experiment 1. However, there was no case in which the results elicited by a status condition in Experiment 2 differed significantly from its matching condition in Experiment 1. The overall pattern differed because the lower and higher conditions in Experiment 2 were slightly higher than in Experiment 1 (p's>.25), and the equal condition was slightly lower (p=.13). Therefore a follow-up experiment (2A) was conducted to see whether this result represents signal or noise.

Status did not significantly affect women's choices on the resource gain problem (L=61%, E=25%, H=35%: χ2(2, n=58)=5.44, p=.07, φ=.31). There was a marginal effect of status (p=.07), but the pattern did not fit dominance theory, risk-sensitive foraging theory or the pattern observed for women's choices on the resource loss problem (the only significant difference was between the lower and equal conditions: L>E: z=−2.25, p=.02, φ=.37; E vs. H: z=0.69, p=.49, φ=.11; L vs. H: z=1.61, p=.11, φ=.26). This pattern did not replicate in a follow-up experiment (2A), so it is not interpreted further.

As in Experiment 1, social status did not significantly affect women's choices on the medical problems, whether they were framed in terms of loss of life (L=63%, E=40%, H=42%: χ2(2, n=58)=2.52, p=.28, φ=.21) or gains in longevity (L=63%, E=50%, H=41%: χ2(2, n=59)=2.03, p=.36, φ=.19).

4.1. Method, Experiment 2A (women) 

4.2. Results and discussion for 2A 

Women showed no status effects to the resource loss problem inExperiment 1, but a significant (resource loss) and a marginal (resource gain) effect of relative status inExperiment 2, in unexpected (and dissimilar) patterns. Were these status effects replicable? No. Women in 2A showed no status effects in response to either resource problem (loss: L=31%, E=27%, H=31%; χ2(2, n=78)=0.12, p=.94, φ=.04; gain: L=35%, E=42%, H=31%; χ2(2, n=78)=0.78, p=.67, φ=.10).

As Fig. 2 shows, the responses of UCSB women to the resource loss problem in 2A were almost identical to those of F&M women in Experiment 1. In short, the unexpected resource loss pattern for UCSB women in Experiment 2 did not replicate, suggesting that it represented noise rather than a real difference between populations. Indeed, Fig. 2 reveals that the means for each status condition are similar across all three experiments.

Although the resource gain problem had elicited a marginal status effect in Experiment 2 (with risk chosen most often by women in the lower status condition), the same problem elicited no status effects at all in 2A.

Replicating the results for the medical loss problem with anonymous others in 2Experiment 1, 3Experiment 2, it was found that relative status did not affect women's risky choices on the medical friends problem (L=62%, E=46%, H=69%: χ2(2, n=78)=2.97, p=.23, φ=.20).

4.3. Method, Experiment 2B (men) 

4.4. Results and discussion for 2B 

On loss problems, can men's personal involvement in the outcome explain the fact that resource loss, but not medical loss, elicited effects of relative status in2Experiment 1, 3Experiment 2? No. Men's relative status did not affect their choices on the medical treatment problem, even though the loss of friends' lives implies a high level of personal involvement (L=58%, E=56%, H=33%: χ2(2, n=73)=3.68, p=.16, φ=.23). This confirms the previous interpretation of 2Experiment 1, 3Experiment 2: when resource loss, but not medical loss, elicited status effects, this was because the problems differed in content (resources vs. medical treatments), not because they differed in levels of personal involvement in the outcome.

When men have not just suffered a resource loss, does status affect their risky choices about resources? No. As in Experiment 2, the resource gain problem elicited no status effects (L=50%, E=44%, H=56%: χ2(2, n=74)=0.72, p=.70, φ=.10).

5.1. Evidence for the co-evolution of motivation and cognition 

Motivation rarely plays a role in cognitive accounts of judgment and decision making. When it does, it usually takes the form of a utility curve or preference (but see Fessler et al., 2004, Maner and Gerend, 2007). Risk-sensitive foraging theory is an example. It was developed to account for animal foraging, but its logic is general to all domains in which one must choose between two options. Whether an individual aspires to a specified level of calories, dollars, health, safety, status or anything else, that aspiration could, in principle, be fed into domain-general decision rules that consult the distributions associated with each option and select the one most likely to achieve that aspiration. Motivation enters the picture at only one point: in determining what good or state one wishes to achieve — one's aspiration. Consistent with the hypothesis that the human mind is equipped with risk-sensitive decision rules that take inputs from almost any domain, food is not necessary to elicit decisions from people that satisfy the constraints of risk-sensitive foraging theory: ball and urn tasks will do (Rode et al., 1999; see Barrett & Fiddick, 1999).

Yet the experiments reported herein suggest that these same decision rules were not activated by an aspiration for status. There were no cases in which the pattern of risk taking tracked the predictions of risk-sensitive foraging theory; moreover, resource gain scenarios failed to elicit status effects — they should have if the only motivational variable involved was an aspiration for resources or status. It is as if risk-sensitive decision rules were pre-empted by the activation of a more specialized system: a cue-activated system designed to regulate men's motivations to take competitive risks in dominance/status interactions (see Fiddick, Cosmides & Tooby, 2000, on the principle of pre-emptive specificity).

This account turns the relationship between motivation and cognition on its head. Rather than aspirations, desires and other motivational variables serving as inputs to domain-general decision rules, we are proposing that men's responses were produced by a motivational system specialized for regulating competitive interactions, which is equipped with its own, proprietary decision rules. Faced with a potential competitor, this system computes a status index: an internal regulatory variable whose magnitude reflects the individual's status relative to the competitor (Tooby, Cosmides, Sell, Lieberman, & Sznycer, in press). Decision rules proprietary to the motivational system — ones that are dormant until the system has been activated — use the status index, the computed value of the resource, and other variables to up- and down-regulate one's motivation to take competitive risks. By hypothesis, these specialized decision rules were not designed to meet an aspiration level for money, status or anything else. Their evolved function is regulatory: to produce levels of risk-taking behavior that would have been adaptive in ancestral situations of resource competition.

The results suggest that this motivational system, like other evolved systems, is cue activated (Barrett, 2005, Cosmides and Tooby, 2000, Haley and Fessler, 2005, Sperber, 1994). It comes online when there are ancestrally reliable cues of impending resource competition. In these experiments, men had not actually lost resources to others; they were merely imagining that situation. Yet believing that other men would be watching and evaluating their decisions — decisions that would reveal how much risk they would be willing to take to recover resources they had lost — was sufficient to elicit dominance theory's inverted U-shaped pattern of risk taking in response to relative status. Men imagining resource loss behaved as if their evaluators were — or would soon become — competitors in a zero-sum contest for resources. The task may have been paper-and-pencil with no actual money at stake and the loss may have been imaginary, but relative status regulated men's motivation for risk nevertheless.

When judged by the standards of mathematics or economics, men's risky decision making in these experiments may seem irrational, but their choices did conform to a normative theory: the evolutionary logic of dominance interactions. This normative theory is rooted in the average fitness payoffs associated with alternative courses of action in the intimate social world of our ancestors. Results reported here illustrate how the principles governing judgment under uncertainty can be both well engineered, yet different across different adaptive problem domains. Indeed, these findings suggest that motivational domains trigger qualitatively different cognitive procedures, undermining the traditional assumption that the only role of motivation is to generate preferences.