Contact Information:
Aaron Sell
School of Criminology
Griffith University, Mount Gravatt
176 Messines Ridge Road
Mount Gravatt, QLD, 4121





















































My research shows that bicep circumference is a good predictor of anger, entitlement, and support for warfare among men but not women.








Subjects can assess strength and fighting ability from the body and face: A + B (UCSB students), C (Tsimane Indian), D (Andean pastoralist)





My research program has centered on the emotion of anger (e.g., see my 2009 paper in the Proceedings of the National Academy of Sciences), as well as mechanisms that regulate the expression of and responses to aggression (see, e.g., my 2008 paper in the Proceedings of the Royal Society).  I focus on questions such as: What functions did anger evolve to serve?  How are its design features organized to serve these functions?  What triggers anger?  How are individual differences in anger-proneness functional responses of the anger system to individual circumstances?  What role does anger play in organizing arguments?

I use a broad variety of methods to attack these questions.  My work includes experimental studies involving children and adults, survey data, collaboration with psychologists and anthropologists working with indigenous people, and physiological measurements.  My research is informed by the recognition that the human psychological architecture is the product of evolution, and by the recognition that this architecture evolved as an information processing system designed to regulate behavior adaptively under ancestral circumstances.  Consequently, my empirical studies and theoretical papers touch on issues and debates within several academic fields, including cognitive psychology, social psychology, developmental psychology, experimental economics, biological anthropology, cultural anthropology, and cognitive science.

Much of the research I have conducted was done in the lab on college students.  However, I believe that research conducted across cultures and age groups is particularly important for testing hypotheses about species-typical psychological design, and for understanding individual and cultural variation in a principled way.  Therefore, in addition to research conducted on US adult and child samples, my collaborators and I have gathered data on and conducted experiments in Argentina, Ecuador, Bolivia, Romania, Denmark, Australia and the Central African Republic.

Theoretical Framework

My research projects test predictions derived from a theory I have developed called the recalibrational theory of anger.  That is, anger—like other emotions—is the expression of an underlying neural program whose organization or logic was constructed over evolutionary time because of the benefits it gave to the individuals equipped with it.  The theory posits that a large and well-bounded subset of phenomena involved in anger is the output of adaptations designed by natural selection to regulate behavior and physiology to resolve conflicts of interest in favor of the angry individual.  Simply put, anger is an implicit bargaining system designed to negotiate for better treatment.  More precisely, the claim is that the regulatory logic built into anger is designed to orchestrate behavior in the angry individual in order to create incentives in the target of the anger to recalibrate upwards the weight he or she puts on the welfare of the angry individual.  Anger is triggered when the mind detects that another person is not putting sufficient weight on the welfare of the angry individual.  The weight one individual places on another’s interests compared to their own can be characterized by what we call a Welfare Tradeoff Ratio (WTR).  My colleagues and I have assembled evidence indicating that the WTR is a psychologically real regulatory variable in the brain that sets the magnitude of the weight the individual places on a specific person’s welfare compared to their own in making decisions that impact them both.  The higher one’s WTR toward another, the less willing one is to impose costs on them and the more willing one is to accept costs to benefit them.

According to the recalibrational theory the major cause of anger is exposure to new evidence that another has a low Welfare Tradeoff Ratio, i.e. that another does not value one’s interests highly enough (according to the anger system’s calculation of entitlement).  When activated, the anger program then deploys the two interpersonal negotiating tactics available to organisms: inflicting costs (e.g. aggression) and withdrawing or downregulating expected benefits.  The function of these tactics is to recalibrate the target of the anger by showing the target that it will be worse off by continuing to behave in ways that place too little weight on the actor’s interests. In this view, the naturally selected function of anger is to recalibrate the WTR in the target’s brain, increasing its magnitude so that the target subsequently places more weight on the welfare of the angry individual.

This perspective synthesizes a number of diverse findings on anger that have been separately addressed by competing theories, putting them into a single functional framework that can be used to make novel predictions.  I have tested predictions from the recalibrational theory on issues such as the role of intentionality in anger, the role of justification, the computational “grammar” of anger-based arguments, the escalating nature of aggression, the communicative features of aggression, the design of the anger face, vocal changes associated with aggression, and finally individual differences in proneness to anger and aggression in men and women.

Empirical Studies

On the causes of anger

According to legal theories of punishment, in order to deter criminals the amount of punishment must scale to the benefit the offender received from the offense, e.g. if someone steals $10 you can impose a fine of $11 but if $1000 was stolen you must raise the fine to $1001.  Many theories (such as equity theory) argue that anger functions the same way.  On the other hand, the recalibrational theory predicts the opposite.  A low Welfare Tradeoff Ratio is indicated by the imposition of a large cost for a small benefit.  When a cost is held constant, the less someone benefits the lower their WTR toward the actor must be, e.g. if someone imposes a cost on you of 10 for a benefit of 2, the most they could value your welfare compared to their own is 1:5; but if that person imposed the same cost (10) for a benefit of 20, then the most they could value your welfare is 2:1 in your favor.

Collaborators and I have run over a dozen studies (at UC Santa Barbara, two Universities in western Romania, one University in Denmark, one University in Australia, and among the Shuar Indians of Ecuador) which tested this basic prediction in addition to more nuanced aspects of the recalibrational theory.  Results show that across all tested populations individuals became less angry when harmed for a large benefit compared to a small benefit.  These results are divided into two papers, one relating directly to dyadic anger and is being composed for publication in the journal Cognition, the other presents data relating Welfare Tradeoff Ratios to attitudes about crime and punishment and has been published in Evolution and Human Behavior. I have also published the logic of the argument with supporting evidence in Aggression and Violent Behavior. My collaborators and I have also published the central argument in two book chapters, one in Human Aggression and Violence, edited by Phil Shaver and Mario Mikulincer, and the other in Human Morality and Sociality, edited by H. Høgh-Olesen.

Anger and arguments

For over thirty years anger researchers have known that the most common behavioral response to an episode of anger is to have an argument.  Despite that, no major theory of anger or aggression attempts to account for the structure of arguments.  The recalibrational theory of anger, however, suggests that arguments are an early and low cost attempt to modify variables relevant to the setting of Welfare Tradeoff Ratios.  When anger is the result of a cost imposition, it predicts that angered individuals should argue that the cost imposed on them was high and the benefit gleaned for imposing that cost was low, i.e. that the offender acted with a low welfare tradeoff.  I tested these predictions in experiments on Ecuadorian foragers and US, Australian and Romanian college students.  In addition, a database of over three hundred arguments were collected on US and Australian college students and analyzed by coders.  Results were the same for all populations and across both methodologies.  Angry individuals select arguments that map directly onto the indicators of a low Welfare Tradeoff Ratio. The data collection and analysis phase of this research has been conducted, and the publication is presently being composed for publication.

On individual differences in anger

The recalibrational theory predicts that some individual differences in thresholds for anger result from the relative bargaining power between the angry individual and the target of anger.  Individuals with more bargaining power will be more likely to be successful and thus are predicted to set lower thresholds for anger.  Ancestrally, the two primary sources of bargaining power were the ability to impose costs (e.g. aggression) and the ability to withdrawal or remove benefits.  The recalibrational model of anger therefore predicts that individuals with enhanced abilities to inflict costs or to confer benefits will anger more easily.  The higher the WTR one expects from others (i.e., the higher the anger system sets the threshold of acceptable WTRs from others), the larger the set of welfare tradeoffs that the anger system will process as unacceptable, and anger provoking.

Many factors contribute to the ability to inflict costs or confer benefits, and so should generate principled individual differences in anger.  I selected two for an empirical test of the model: physical strength, which ancestrally related to the ability to impose costs, and attractiveness, which related to the ability to confer benefits.  My collaborators and I have gathered data showing links between physical strength in men and anger, entitlement, and attitudes about the use of force on a personal and political level in the US, Romania, Ecuador, Bolivia, Denmark, Argentina, Australia and the African Congo.  Additional data in the United States and Romania showed the predicted positive correlations physical attractiveness and anger and entitlement in women.  These results have been published in the Proceedings of the National Academy of Science, Human Nature, and Psychological Science.

On evidence for neurocognitive adaptations for assessing fighting ability from body, face, and voice

Because of the role that cost infliction (i.e. formidability) plays in anger and other domains, I predicted that humans would, like many other animals, have competence at assessing fighting ability.  Collaborators and I used weight-lifting machines, physiometric measurements validated on weight-lifting machines, and peer-ratings to determine physical strength and fighting ability among US and Romanian college students, Argentine pastoralists, and Bolivian and Ecuadorian horticulturalists.  First, we found that subjects’ assessments of fighting ability tracked subjects’ perceptions of the targets’ upper body strength almost exactly—ancestrally, fighting ability would have been based largely on upper body strength, and the mind still equates them.  In testing the hypothesis that humans are spontaneously good at assessing fighting ability, we found that subjects could accurately assess physical strength from photographs of the body, photographs of just the face, and from voice samples.  A number of analyses suggest that this ability is an evolved competence and not simply the result of a learning mechanism that maps cues of strength onto features of the face and voice.  These include:

  • Consistent with a more intense selective history of aggression among ancestral males than females, both male and female raters were more much more accurate when rating male targets than female targets.
  • Raters assessed physical strength with equal accuracy regardless of the raters’ familiarity with the culture and, in the case of voice ratings, with the language that was being spoken, i.e. having grown up and spent one’s entire life with speakers of one language had zero impact on one’s ability to assess physical strength from those voices.
  • When peer ratings of fighting ability were available (among the Tsimane Indians of Boliva) the accuracy of strength detection was entirely mediated by fighting ability, i.e. raters are extracting cues of fighting ability not simply physical strength.
  • Hierarchical Linear Modeling (HLM) analyses showed that raters extracted cues of physical strength that were predictive even controlling for height and weight, i.e. cues in the face and voice indicate upper body strength rather than just body size
  • Furthermore, I recently collected data from a cross-sectional study of American preschoolers (aged 3-5) that shows this ability appears at age four even when tested on adult faces.  This finding will be submitted to Developmental Science.

Results have been published in two papers in the Proceedings of the Royal Society (Biological Sciences), and discussed at length in a book chapter on how evolutionary approaches can illuminate long standing problems in psychology, published in Vonk & Shackelford's Oxford Handbook of Comparative Evolutionary Psychology