Development of an Instrument to Assess Expectations for the Use of Online Gaming, Social Networking Sites, and Online Pornography: the Marburg Internet Use Expectations (MINUS-X) Questionnaire

User's expectations contribute to the maintenance of problematic use of online gaming (OG), social networking (SN), and online pornography (OP). Since an instrument to assess use expectations across applications is lacking, this study aimed at developing and testing such a questionnaire. It consists of a general module (GM), which includes expectations relevant to all three applications, and three application-specific modules. A pilot and a validation study were conducted with 2880 German adults. We conducted item analyses, exploratory factor analyses (EFA), exploratory structural equation modelling, and correlation analyses. The EFA revealed six factors for the GM and two factors for each specific module. The GM demonstrated measurement invariance between applications. The instrument showed excellent psychometric properties, indicating its suitability for assessing expectations concerning the use of OG, SN, and OG reliably and validly. It could be helpful for treating patients with problematic use of the applications and investigating the role of the relevant expectations.