Rusbult's Investment Model and the Expansion of the Self‐Expansion Model

From the outset, our development of the selfexpansion model (Aron & Aron, 1986) was to a substantial extent explicitly in the larger context of Kelley and Thibaut’s (1978) interdependence theory. We saw self-expansion, especially when it occurs through including the other in the self in a close relationship, as a major source of positive outcomes when considering one’s comparison level and comparison level of the alternative. With the development of Caryl Rusbult’s enormously influential investment model (first described in Rusbult, 1980; for results of a recent metaanalysis, see Figure 1), the role of interdependence ideas became more precise and more valuable in shaping the development of our own theoretical and empirical work. Sometimes this shaping resulted from needing to make more careful distinctions. One example is the distinction between the interdependence ideas of transformation of motivation and the self-expansion idea of including other in the self as they apply to mixed-motive situations. On the one hand, seminal studies such as Yovetich and Rusbult (1994) suggest that the primary “gut” reaction to an interdependence dilemma (conflicting desires of self and partner) is selfish and that only with time for reflection does it get transformed to a desire to maximize joint outcomes. Our view, on the other hand, was that close others are included in the self so that to some extent one’s immediate response to a conflict of this kind considers partner’s outcomes just as one’s own (e.g., Aron, Aron, Tudor, & Nelson, 1991, Study 1). Having been faced with this seeming contradiction, our eventual thinking (e.g., Aron, Mashek, & Aron, 2004) was that both operate but under different conditions. That is, in a close relationship the other is never identical to self but only included to some extent. Thus, we argue, to the extent the other is included in self (especially in circumstances that make the overlap of selves salient), the immediate response gives equal weight to partner and self. However, to the extent the other is not included in the self (especially in circumstances that make the lack of overlap salient), there will be an immediate self-oriented feeling. In this latter circumstance, following Rusbult, if there is sufficient commitment to the relationship, with a bit of extra time one will suppress the selfish response and transform the motivation for the benefit of the relationship. These ideas actually got worked out initially in an intense debate between Caryl and Art that took place during the questionand-answer period in a symposium at a major social psychology conference. Another example of the generative process of clarification from subtle differences is an ongoing collaborative project that began when one of our then graduate students, Bianca Acevedo, spent a summer in Caryl’s laboratory in Amsterdam (and in which Madoka Kumashiro, then a postdoc working with Caryl, has played a major role). Here the goal has been to apply two related ideas to understanding the possible positive effects on