Evidence across the social and behavioral sciences points to psychological mechanisms that facilitate the formation and maintenance of interpersonal commitment. In addition, evolutionary simulation studies suggest that a tendency for increased, seemingly irrational commitment is an important trait of successful exchange strategies. However, empirical research that tests corresponding psychological mechanisms is still largely lacking. Here an experimental test is proposed for one such mechanism, termed the commitment bias, which is hypothesized to increase people's commitment to existing partners beyond instrumental reasons. To exclude one alternative explanation, the commitment bias is distinguished from uncertainty reduction. Results from a cross-culturally replicated laboratory experiment (USA, China, and the Netherlands) provide support for the argument but also point to the importance of culture as an alternative or mediating factor.
Building and maintaining long-term social relationships is a natural part of human life and a behavior observed universally in all societies (Baumeister & Leary, 1995). People create relationships with great ease and are often reluctant to dissolve them, even if other alternatives are available. What makes people hold on to relationships in situations when this is apparently not in their best interest?
According to standard rational choice explanations of long-term relationships, people repeatedly interact with each other when the benefits of a relationship outweigh its maintenance and alternative costs (Axelrod, 1984, Cook and Emerson, 1978, Hayashi and Yamagishi, 1998, Lawler and Yoon, 1996 and Rusbult et al., 1998). First, having a long-term relationship with the same partner provides direct knowledge about the past behavior and thus the trustworthiness of a partner (“shadow of the past”). This makes a previous partner relatively more attractive than an unknown individual. Second, the prospect of recurring benefits from future mutual cooperation creates an incentive for existing partners to cooperate in the present, knowing that noncooperation could trigger retaliation by the partner and thus jeopardize future payoffs (“shadow of the future,” see Axelrod, 1984).
On the other hand, a great wealth of empirical evidence (cf. Baumeister & Leary, 1995) suggests that people have a tendency to become emotionally attached to each other, with less regard for the direct benefits derived from the relationship, its maintenance, or alternative costs. People create social relationships with great ease and strongly resist the dissolution of these relationships, well beyond rational considerations of practical advantage.
A series of recent simulation studies explore the possibility of the evolution of a “commitment bias,” which could be an important psychological step in the process of commitment formation (Back and Flache, 2006, Back and Flache, 2007, Back and Flache, 2008, de Vos et al., 2001 and Smaniotto, 2004). These computational models are built on minimalistic assumptions about conditions of the ancestral environment, such as relatively small group size, food shortage, and increased need for mutual help. What these models show consistently is that when compared with strongly selfish or conditionally cooperative strategies, commitment emerges as the most viable strategy under a wide range of environmental conditions.
For the rest of this article, “commitment” will refer to the behavior of repeatedly selecting the same partner even in the presence of potentially better alternative partners, and “commitment bias” will refer to a seemingly irrational psychological tendency that is hypothesized to partially induce people to do so.
The purpose of this article is to experimentally test the existence of a commitment bias. To do so, a short, anonymous, instrumental market setting is used where instrumental aspects of relationships are more salient, and at the same time the influence of non-instrumental factors can be more closely controlled. In such a setting, we have no reason to expect people to diverge from standard rational behavior toward commitment formation, unless there exists a systematic decision-making bias that pushes them to do so.
