Krause Hannes-Vincent

• Social Networking Sites (SNSs) are ubiquitous and attract an enormous chair of the digital population. Their functionalities allow users to connect and interact with others and weave complex social networks in which social information is continuously disseminated between users. Besides the social value SNSs are generating, they likewise attract companies and allow for new forms of marketing, thereby creating considerable economic value alike. However, as SNSs grew in popularity, so did concerns about the impact of their use on social interactions in general and the well-being of individual users in particular. While existing scientific evidence points to both risk as well as benefits of SNS use, research still lacks a profound understanding of which aspects of SNSs enable an impact on well-being and which psychological processes on the part of the users underly and explain this relationship. Therefore, this thesis is dedicated to an in-depth exploration of the relationship between SNS use and well-being and aims to answer how SNS useSocial Networking Sites (SNSs) are ubiquitous and attract an enormous chair of the digital population. Their functionalities allow users to connect and interact with others and weave complex social networks in which social information is continuously disseminated between users. Besides the social value SNSs are generating, they likewise attract companies and allow for new forms of marketing, thereby creating considerable economic value alike. However, as SNSs grew in popularity, so did concerns about the impact of their use on social interactions in general and the well-being of individual users in particular. While existing scientific evidence points to both risk as well as benefits of SNS use, research still lacks a profound understanding of which aspects of SNSs enable an impact on well-being and which psychological processes on the part of the users underly and explain this relationship. Therefore, this thesis is dedicated to an in-depth exploration of the relationship between SNS use and well-being and aims to answer how SNS use can impact well-being. Primarily, it focuses on the unique technological features that characterize SNSs and enable potential well- being alterations and on specific psychological processes on the part of the users, underlying and explaining the relationship. For this purpose, the thesis first introduces the concept of well- being. It continues by presenting SNSs’ unique technological features, divided into specifics of the content disseminated on SNSs and the network structure of SNSs. Further, the thesis introduces three classes of psychological processes assumed most relevant for the relationship between SNSs and well-being: other-focused, self-focused, and contrastive processes.. It is assumed that the course and quality of these common processes change in the SNS context and that a complex interplay between the unique features of SNSs and these processes determines how SNSs may ultimately affect users' well-being - both in positive and negative ways. The dissertation comprises seven research articles, each of which focusses on a particular set of SNS characteristics, their interplay with one or more of the proposed psychological processes, and ultimately the resulting effects on user well-being or its key resilience and risk factors. The seven articles investigate this relationship using different methodological approaches. Three articles are based on either systematic or narrative literature reviews, one applies an empirical cross-sectional research design, and three articles present an experimental investigation. Thematically, two articles revolve around SNS use’s effect on self-esteem. Three articles examine the specific role of the emotion of envy and its potential to establish and perpetuate a well-being-damaging social climate on SNSs. The two last articles of this thesis revolve around the established assumption that active and passive SNS use, as different modalities of SNS use, cause differential effects on users’ well-being due to the involvement of different psychological processes. The results of this thesis illustrate different ways how SNSs can affect users’ well-being. The results suggest that especially contrastive processes play a decisive role in explaining potential well-being risks for SNS users. Their interplay with certain SNS features seems to foster upward social comparisons and feelings of envy, potentially leading to a complex set of deleterious effects on users’ well-being. At the same time, the findings illuminate ways in which SNSs can benefit users and their self-esteem – especially when SNS use promotes self- focused and social-feedback-based other-focused processes. The thesis and their findings illustrate that the relationship between SNSs and well-being is complex. Therefore, a nuanced perspective, taking into consideration both the technological uniqueness of SNSs and the psychological processes they are enabling, is crucial to understand how these technologies affect their users in good and potentially harmful ways. On the one hand, the gathered insights contribute to research, providing novel insights into the complex relationship between SNS use and well-being. On the other hand, the results enable a focused and action-oriented derivation of recommendations for stakeholders such as individual users, policymakers, and platform providers. The findings of this thesis can help them to better combat SNS-related risks and ultimately ensure a healthy and sustainable environment for users - and thus also the economic values of SNSs - in the long term.…