How to Trust: A Model for Trust Decision Making

Introduction

Trust and trustworthiness (Hardin, 2002) capture many different aspects that are becoming as critical and relevant as many other aspects (e.g., safety, security, dependability) for system design and assessment (Camp, 2003; Yu & Liu, 2001). Research on trust drawn from multidisciplinary domains highlights a continuing debate on its definition and its nature (Gambetta, 1998; Harding, 2002, 2006; McKnight & Chervany, 1996). Yet, it is difficult to derive a definitive and widely-accepted definition of trust. One conclusive remark is that trust is a complex concept. Unveiling its complexity requires us to understand subtle interactions among different aspects of trust (e.g., trust and trustworthiness).

This paper reviews relevant research accounts on trust in order to identify the main trust aspects and analyze their interdependencies. These interdependencies highlight a structured trust decision model, which allows us to discuss and clarify trust matters systematically. The underlying interdependencies among aspects of trust characterize different decision making processes that act on trust. Moreover, they stress the distinction between deciding to trust (i.e., the decision of whether or not to trust) and acting on trust (i.e., any action or activity that might depend on trust). This distinction enables us to analyze different trust situations (e.g., definitions of trust requirements). Furthermore, understanding interactions among trust aspects is instrumental in order to analyze different decision making processes (e.g., unconscious actions or decisions, and informed or rational choices). This characterization of trust emphasizes differences between decision making processes in the general public (e.g., how people act or decide to trust) and in the informed peer groups (e.g., how people who have the capacity to access and interpret trust-related information decide to trust). On the one hand, it captures the sociality of trust. That is, it highlights the fact that trust is a social matter. On the other hand, it embraces the rationality of trust. That is, it takes into account trust as being rational. This paper advocates the investigation of how to relate trust, risk, and knowledge uncertainty to each other. One course of investigation is to look at them from a social perspective of trust (Krukow & Nielsen, 2007). Though, it is necessary to enrich such account by cultural aspects (which make possible to distinguish organizations, groups, etc.) and rational domain knowledge in order to tailor them to situated contexts.

This paper is structured as follows. The next section provides a brief review of relevant work on trust in order to stress the complexity of the concept itself. Moreover, it identifies and describes some general aspects that characterize trust. It then introduces our structured account of trust, or trust decision model. The rationale is twofold. First, it is necessary to provide a systematic approach to clarify trust in situated contexts. Second, a systematic account is also useful in order to analyze decision making processes that rely on trust. The proposed trust decision model is used to analyze and structure different situational trust problems. It finally discusses how such trust problems relate to trust and relevant policies, and draws some concluding remarks.