I work as an associate professor in the Interaction Group at Utrecht University, the Netherlands.  My research focuses on the fine balance between the benefits of personalization and perceived and actual risks associated with privacy matters. Particularly, I investigate how users and current (commercial) recommender systems respond to one another, and which mechanisms help to encourage users to actively choose what they want instead of passively following suggestions.

My main research interests include user modeling, personalization, Web usage mining, data analysis and visualization, usability and user evaluation. On my Research Blog you can read about current developments and results, plus some ramblings.

From 2017 until June 2022, I was an assistant professor at the Digital Security Group at Radboud Universiteit Nijmegen, the Netherlands, where I coordinated the Master Program in Information Sciences. Earlier, between 2006 and 2017, I worked as a senior researcher at the L3S Research Center in Hannover, Germany, where I conducted research in the related domains of user modeling, personalization and Web Science.

Since July 2019, I am Vice Chair of ACM SIGWEB. I am board member and information officer of User Modeling Inc and between 2007 and 2015, I served as the chair of the German SIG on Adaptive Systems and Interactive Systems ABIS. Further, I currently serve as General Chair for ACM UMAP 2021 and as Program Chair for ACM Hypertext 2021 - see the announcements below for more details. I was General Chair for the  UMAP 2017 conference in Bratislava, Slovakia and the Hypertext 2016 conference in Halifax, Canada. Hypertext 2016 was collocated with UMAP 2016. I served as Program Chair for the Hypertext 2014 conference, which took place in Santiago de Chile. I served as Local Chair of the Adaptive Hypermedia 2008 conference, Publicity Chair for CHI 2012, UMAP 2010 and UMAP 2011, as Workshop and Tutorial Chair for UMAP 2012 and as Poster and Demo Chair for UMAP 2013.

I was involved in the European project EUMSSI and the German BMBF project GlycoRec on daily personalized support for diabetes patients. Previously, I was involved in the European projects LinkedUpStellarGrapple and Sync3, in which I worked as local team leader and work package manager. I was general manager of the Prolean NoE, which finished successfully in 2008. Apart from project coordination, I supervise Ph.D. students and give lectures.