Kim, John S.2013-10-182013-10-182013-08https://hdl.handle.net/11299/158564University of Minnesota Ph.D. dissertation. August 2013. Major: Psychology. Advisors: Jeffry A. Simpson and Mark Snyder. 1 computer file (PDF); vii, 125 pages, appendices A-E.Sex ratio is defined as the proportion of males to females in a given local environment, and it is a situational cue with profound implications for how humans approach their romantic relationships (Guttentag & Secord, 1983). According to theory, individuals in relationships should value their relationships more highly and engage in more behavior to maintain their relationships when faced with an unfavorable sex ratio (i.e., fewer opposite-sex members), relative to when they are faced with a favorable sex ratio (i.e., more opposite-sex members). However, no experimental work has examined the influence of sex ratio on romantic relationships. In the current dissertation, I addressed this gap in the literature by experimentally testing a series of predictions regarding the influence of sex ratio on how individuals think and behave within their relationships. The data supported the contention that individuals faced with a relatively unfavorable sex ratio value their relationships more highly and engage in more relationship maintenance behavior. However, men and women demonstrated different behavioral strategies given a relatively unfavorable sex ratio, with men engaging in direct intervention to fend off competitors and women engaging in more indirect behavior in service of maintaining relationship harmony. Moreover, given a relatively unfavorable sex ratio, men showed cognitive changes about their partner's likelihood of committing infidelity in a manner consistent with direct intervention, while women showed increases in other relationship domains consistent with their indirect behavioral strategy.en-USRomantic relationshipsSex ratioThesis or Dissertation