The social functions of the emotion of gratitude via expression.

Recent theory posits that the emotion of gratitude uniquely functions to build a high-quality relationship between a grateful person and the target of his or her gratitude, that is, the person who performed a kind action (Algoe et al., 2008). Therefore, gratitude is a prime candidate for testing the dyadic question of whether one person's grateful emotion has consequences for the other half of the relational unit, the person who is the target of that gratitude. The current study tests the critical hypothesis that being the target of gratitude forecasts one's relational growth with the person who expresses gratitude. The study employed a novel behavioral task in which members of romantic relationships expressed gratitude to one another in a laboratory paradigm. As predicted, the target's greater perceptions of the expresser's responsiveness after the interaction significantly predicted improvements in relationship quality over 6 months. These effects were independent from perceptions of responsiveness following two other types of relationally important and emotionally evocative social interactions in the lab, suggesting the unique weight that gratitude carries in cultivating social bonds.