Psychology ETDs

Publication Date

Fall 9-14-2016


Oxytocin (OT) is a mammalian neuropeptide hormone that has been extensively studied in the field of obstetrics and mother-infant bonding. More recently, animal and human studies have suggested that OT might also have important functions within sexual pair-bonds. While some have advanced the perspective that OT is a ‘bonding’, ‘cuddle’, or ‘trust’ hormone, a number of opposing findings cast doubt on such interpretations. Several research groups have attempted to address this so-called ‘paradox’. I propose a different type of framework that attempts to address this paradox, but perhaps more importantly, also aims to provide additional explanatory power regarding the functions of OT within human romantic relationships—and perhaps other types of close bonds, as well. This theoretical framework has four central properties. First, it considers the adaptive design of the OT system as a central issue; OT should be ‘tagged’ to specific intimate social partners such as offspring or mates, rather than functioning as a general-purpose hormone for prosociality. Second, it builds upon theoretical models in evolutionary biology suggesting that endocrine hormones function as messengers coordinating biological activity across an organism in an adaptive fashion. Third, it emphasizes the inevitability of trade-offs in an organism’s energy allocation decisions, and proposes that hormones evolved, in part, to mediate these trade-offs. Fourth, it also emphasizes the contingency of biological responses on appraisals of environmental conditions, such as current budgets and future resource availability. To test these ideas, I recruited 148 Norwegian participants in committed romantic relationships and assessed how facets of one’s romantic relationship, perceptions of assistance from the ‘Nordic Welfare State’, and investment in social bonding outside the romantic relationship predicted changes in OT across a thought-writing task regarding one’s partner. Results were mixed. Replicating a recent finding in American couples (Grebe et al., 2016), participants who were highly involved in their relationships, but felt that their partner was less involved, had the largest OT increases across the task. In other words, OT increases reflected discrepancies between assessments of self and partner relationship involvement. Across multiple measures, there was no consistent indication that perceptions and attitudes regarding state welfare, either alone or interacting with relationship involvement, influenced OT responses. Finally, individuals with stronger OT responses, and who reported greater discrepancies in romantic relationship involvement, reported less interest in certain kinds of social bonding outside the relationship, consistent with a trade-off between classes of social bonding effort. In light of these results, I discuss the value of replication in psychological research, strengths and weaknesses of the proposed theoretical framework, and potential directions for future research.

Degree Name


Level of Degree


Department Name


First Committee Member (Chair)

Steven W. Gangestad

Second Committee Member

Melissa Emery Thompson

Third Committee Member

Marco Del Giudice

Fourth Committee Member

Leif Edward Ottesen Kennair




oxytocin, romantic relationships, cross-cultural psychology, Norway, life-history theory

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Included in

Psychology Commons