An investment model of sociosexuality, relationship satisfaction, and commitment: Evidence from dating, engaged, and newlywed couples Gregory D. Webster a,⇑ , Jean-Philippe Laurenceau b , C. Veronica Smith c , Amanda L. Mahaffey d , Angela D. Bryan e , Amy B. Brunell f a University of Florida, USA b University of Delaware, USA c University of Mississippi, USA d Instituto Universitário de Lisboa, Portugal e University of Colorado Boulder, USA f The Ohio State University at Mansfield, USA article info Article history: Available online 25 February 2015 Keywords: Romantic relationships Sociosexuality Actor–partner interdependence model Investment model Moderated mediation Satisfaction Commitment abstract Using an investment model (Rusbult, 1980, 1983) of sociosexual attitudes (SOI-A), we examined SOI-A’s association with relationship outcomes using actor–partner interdependence models (APIMs) of over 400 dating, engaged, and newlywed couples. Men’s SOI-A negatively related to both men’s (actor effect) and women’s (partner effect) relationship satisfaction. This actor effect persisted after controlling for men’s and women’s relationship commitment, and was stronger (more negative) among dating couples (vs. engaged or newlywed couples) and couples with shorter relationship durations. Moderated-mediation APIMs suggested that (a) both actor-effect satisfaction–commitment associations were more positive in couples dating for 6 months and (b) men’s relationship satisfaction mediated the link between men’s SOI-A and men’s relationship commitment, but only in couples dating for 6 months. Ó 2015 Elsevier Inc. All rights reserved. 1. Introduction Sociosexuality describes individual differences in people’s atti- tudes and behaviors regarding casual sex with multiple partners (Simpson & Gangestad, 1991). People with unrestricted sociosexual orientations are comfortable having sex without commitment, whereas people with restricted sociosexual orientations feel that relationship commitment is necessary for sexual activity. Sociosexually restricted people often pursue (serial) monogamy, whereas more unrestricted people are comfortable with multiple partners. The present study examines how sociosexuality relates to relationship satisfaction and commitment in romantic couples reflecting various relationship types (dating, engaged, and newly- wed) and durations. We begin by examining how sociosexuality relates to satisfaction and commitment in couples within the the- oretical framework of the investment model (Rusbult, 1980, 1983). 1.1. An investment model of sociosexuality Drawing on interdependence theory (Kelley & Thibaut, 1978), the investment model of commitment processes posits that people seek to maximize rewards and minimize costs in relationships (Rusbult, 1980, 1983). Specifically, relationship commitment can be viewed as a function of a person’s investment in the relationship (e.g., time), rewards (e.g., satisfaction), and perceived available alternatives (e.g., sociosexual attitudes). This theoretical founda- tion can be expanded to couples, and to include relationship satis- faction as a mediator linking commitment to investment, alternatives, or personality (Lennon, Stewart, & Ledermann, 2013; Smith et al., 2014). It can even be expanded further to include moderators such as measures of investment (e.g., relationship duration). Because the investment model provides an organized theoretical framework to examine sociosexuality’s role in commit- ment processes, our hypotheses reflect sociosexuality’s link to sat- isfaction, how satisfaction mediates sociosexuality’s link to commitment, and how relationship type (e.g., dating, engaged, or newlywed couples) and duration may moderate these links. Because sociosexuality can be decomposed into behavioral and http://dx.doi.org/10.1016/j.jrp.2015.02.004 0092-6566/Ó 2015 Elsevier Inc. All rights reserved. ⇑ Corresponding author at: P.O. Box 112250, Department of Psychology, Univer- sity of Florida, Gainesville, FL 32611-2250, USA. Fax: +1 352 392 7985. Journal of Research in Personality 55 (2015) 112–126 Contents lists available at ScienceDirect Journal of Research in Personality journal homepage: www.elsevier.com/locate/jrp