Hormones, social dynamics, and variation in responses to inequity in social group settings

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This award was provided as part of NSF's Social, Behavioral and Economic Sciences Postdoctoral Research Fellowships (SPRF) program. The goal of the SPRF program is to prepare promising, early career doctoral-level scientists for scientific careers in academia, industry or private sector, and government. SPRF awards involve two years of training under the sponsorship of established scientists and encourage Postdoctoral Fellows to perform independent research. NSF seeks to promote the participation of scientists from all segments of the scientific community, including those from underrepresented groups, in its research programs and activities; the postdoctoral period is considered to be an important level of professional development in attaining this goal. Each Postdoctoral Fellow must address important scientific questions that advance their respective disciplinary fields. The current project allows for a groundbreaking new way to study social behavior in intact, interacting social groups, both in captive and wild social groups, while collecting information on underlying biological mechanisms to these behaviors. Humans vary in how they respond when receiving less than expected (e.g. contrast) or less than a social partner (e.g., inequity). Inequity is almost ubiquitous in human society, and negative reactions to inequitable circumstances can exacerbate already bad outcomes. Thus, it is critical to better understand what causes humans to respond to negative outcomes, and what factors can exacerbate or, ideally, ameliorate, these reactions. Humans responses to violated expectations are influenced by both individual factors, such as personality, dominance, and hormone profiles, and social factors, such as societal norms, kinship, and relationship quality. One of the weaknesses of human studies is that these factors are often examined independently, with little regard for how social and individual contexts influence one another. Part of the challenge is practical, human societies involve so much complexity that it is nearly impossible to follow all of each individuals' relationships over an extended time period and to control all the circumstances that occur in freely acting social groups. Yet, such a socially typical paradigm is necessary to fully understand how individual differences and real-world group dynamics influence our decisions. This research will address this problem, examining decision-making in a socially relevant, group-level context in capuchin monkeys. Capuchin monkeys are an ideal species in which to study this question. Like humans, capuchins are highly social, routinely cooperate, and systematically experience strong negative reactions to inequity. Yet, all previous studies on inequity in nonhuman primates have been conducted in captivity and the vast majority have relied on how individuals behave when in pairs separated from their social group. As a result, whether capuchins maintain their aversion to inequity in more social and ecologically relevant environment remains unknown. This research will examine response to inequity in intact social groups both at in captivity at Georgia State University and in the field in Iguazu Argentina, allowing the unprecedented opportunity to compare social decision-making in a controlled laboratory setting and in a real-world context. This research has two main goals. First, by implementing a novel, experimenter-free paradigm that allows for remote group testing, this research will investigate how social factors and group dynamics influence responses to inequity. Second, this study will examine the biological mechanisms mediating response to inequity within a social context. Recent research in humans has highlighted the importance of hormones in influencing decision-making behavior. However, again, these studies have been conducted outside of the context of a normal social environment. This research will integrate noninvasive measures of fecal hormone analyses to assess how individual differences in response to inequity may be mediated by hormone levels, or an interaction between hormones and social context, that will be insightful in uncovering the biological mechanisms driving individual differences in decision-making behavior.