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Sarah Brosnan

Associate Professor    ,

Ph.D., Emory University, 2004


Economic decision making behavior in primates; social cognition; evolution of behavior; inequity responses; cooperation; social comparison; ‘irrational’ behaviors


Humans routinely confront situations that require coordination between individuals, from mundane activities such as planning where to go for dinner to incredibly complicated activities, such as international agreements or trans-national ventures, such as the International Space Station. Moreover, despite some failure, we frequently succeed in these situations. How did this ability arise, and what prevents success in those situations in which it breaks down? To understand how this capability has evolved, my lab utilizes an explicitly comparative approach to study the function of and mechanisms underlying decision-making.

At the species level, we explore how individuals in many different species make these decisions, how these decisions differ across species, and what are the underlying mechanisms that support successful cooperation. By determining how these species’ responses correlate with different aspects of each species’ socio-ecology, we can begin to make informed hypotheses about the function of behavior, or why it evolved. For instance, in one line of research we have discovered a correlation between species that respond negatively to inequity and the tendency to cooperate with non-kin outside of family groups. We also find that primates coordinate, but that Old World primates find better outcomes than do New World primates, indicating a split within the primate taxon. At the individual level, we use a similar approach to explore how differences in decision-making outcomes within a species correlate with aspects of individual’s demographic characteristics, such as age, rank, sex, or personality, aspects of their cognition, such as their risk preferences, and social variables, such as individuals’ relationships.

A powerful approach to understanding decision-making is to utilize the methodology of experimental economics. Economic games derived from experimental economics provide opportunities to better understand how and why individuals make the decisions that they do. This approach is of particular utility to comparative researchers. One common challenge to comparative research is that studies may not be comparable due to methodological differences, minimizing the effectiveness of the comparative approach and providing little insight into the evolution of the behaviors. Utilizing an experimental economics approach allows for a standardized methodology that is comparable not only between non-human species, but also to humans, and in particular young children, who have become a recent focus of our work. This allows for more profound insight in to the evolution of decision-making behavior. Many of the research topics in my lab take advantage of this approach.

Aside from being an associate professor in the departments of psychology and philosophy and the Neuroscience Institute at Georgia State University, I am a member of the Brains & Behavior program and the Center for Behavioral Neuroscience. I direct the Comparative Economics and Behavioral Studies Laboratory (CEBUS Lab) and do research with nonhuman primates at both the Language Research Center of Georgia State University and the Michale E. Keeling Center for Comparative Medicine and Research of the UT/MD Anderson Cancer Center, as well as studying both children and adults and other species, such as fish. For more information on my research and my collaborators, please see my website at


For a list of my publications, please see my Google Scholar profile.