This doctoral thesis aims to define collaborative consumption and advance the understanding of its social-psychological determinants and effects. In order to achieve these aims, the thesis presents three studies, each of which has been accepted at scientific conferences and developed further based on feedback from experts and reviewers. Two of the studies have been published in peer-reviewed journals. The introduction provides an overview of collaborative consumption as a comparably sustainable consumption practice. Moreover, three research deficits are identified that are the motivation for the subsequent studies. First, it is shown that the basic idea and the scope of collaborative consumption remain unclear. Second, it is found that understanding of determinants is limited to isolated variables leaving relative strengths of and interdependencies between variables untapped Finally, it is assessed that actual effects of collaborative consumption on consumers’ mindsets are not well understood. The first study titled “Prototypical collaborative consumption behaviors and their relations: A conceptual review and empirical study” examines consumer behaviors that are comprised by the term “collaborative consumption” and the relations between these behaviors. In order to identify prototypical collaborative consumption behaviors, original definitions of collaborative consumption in the literature are reviewed. To derive hypotheses on the relationships between the prototypical behaviors, the study draws on theoretical foundations from the field of consumer lifestyles and behavioral spillover. The second study titled “Understanding collaborative consumption: An extension of the theory of planned behavior with value-based personal norms” aims to understand which social-psychological variables and underlying values and beliefs determine actual collaborative consumption. The theory of planned behavior is used as the primary theoretical framework, as it is a well-established model that has been shown to explain a wide range of consumer behaviors. However, reviews and meta-analyses have found the theory’s ability to account for normative motives to perform a behavior is weak and have called for further theory development. As normative motives are expected to be particularly important in the context of collaborative consumption, the theory is extended with a value-based personal norm variable. The third study titled “Does collaborative consumption affect consumers’ values, attitudes, and norms? A panel study” examines the nature of causality between collaborative consumption and behavioral factors in order to determine whether collaborative consumption affects consumers’ values, attitudes, and norms over time. The study primarily builds on the theory of planned behavior, value theory, and the value-belief-norm theory to determine the theoretical framework linking collaborative consumption, values, attitudes, and norms over time. The theoretical framework is tested based on a two-wave panel over a time period of nine months using survey data from 168 consumers. In conclusion, the thesis contributes to the literature in six ways. First, the thesis conceptually defines collaborative consumption, a term that was used ambiguously so far. Second, it empirically advances the understanding of social-psychological determinants of collaborative consumption. Third, it explains social-psychological effects of collaborative consumption on consumers over time, something that has not been done in the literature before. Fourth, the thesis identifies and examines the relationships between five prototypical collaborative consumption behaviors. Fifth, it argues for the extension of the theory of planned behavior by a value-based personal norm variable and provides supporting empirical evidence. Finally, it advances knowledge on the causal relationship between values, attitudes, norms, and behavior.
