Lay beliefs have long heralded the importance of similarity between romantic partners for relationship success. However, extant research has shown that only perceived similarity—not actual similarity—is associated with higher-quality and more stable romantic relationships. We know little about why this is and what processes explain the link between perceived similarity and positive relationship outcomes.
To begin to answer these questions, we first need to know whether perceived similarity actually leads to positive relationship outcomes, as well as how perceived similarity and relationship outcomes co-develop over the course of a relationship. Doing so requires experimental and longitudinal studies that track the development of perceived and actual similarity and relationship outcomes over time—something few studies have done to this point.
This dissertation includes two studies that address these questions: one, a study tracking the co-development of perceived similarity and romantic interest in a sample of dating app users, and two, an in-lab study experimentally manipulating perceived similarity in established couples. The first study demonstrates that (1) dating app users believe in the importance of similarity for romantic relationships, (2) similarity is cited as a motivation for interest in potential partners, and (3) perceived similarity is more strongly associated with relationship interest than actual similarity throughout the relationship initiation phase.
The second study finds that perceptions of similarity are malleable even among established couples and that couples react negatively to feedback indicating dissimilarity. In this study neither actual nor perceived similarity were robustly associated with relationship quality; however, there was some evidence that individuals’ beliefs about similarity and the ways they discuss dissimilarity with their partner may moderate these associations. Overall, these studies provide insight into the ways similarity operates at different stages of relationships and underscores the importance of perceived similarity in romantic relationships.