Probabilistic Models for the Verification of Human-Computer Interaction Bernhard Beckert and Markus Wagner In this paper, we present a method for the formalization of probabilistic models of human-computer interaction (HCI) including user behavior. These models can then be used for the analysis and verification of HCI systems with the support of model checking tools. This method allows to answer probabilistic questions like "what is the probability that the user will unintentionally send confidential information to unauthorized recipients." And it allows to compute average interaction costs and answer questions like "how much time does a user on average need to send an email?"