Technologies that shape human behavior are of high societal relevance, both when considering their current impact and their future potential. In information systems research and in behavioral psychology, such technologies are typically referred to as persuasive technologies. Traditional definitions like the ones created by Fogg, and Harjumaa and Oinas-Kukkonen, respectively, limit the scope of persuasive technology to non-coercive, non-deceptive technologies that are explicitly designed for persuasion. In this paper we analyze existing technologies that blur the line between persuasion, deception, and coercion. Based on the insights of the analysis, we lay down an updated definition of persuasive technologies that includes coercive and deceptive forms of persuasion. Our definition also accounts for persuasive functionality that was not designed by the technology developers. We argue that this definition will help highlight ethical and societal challenges related to technologies that shape human behavior and encourage research that solves problems with technology-driven persuasion. Finally, we suggest multidisciplinary research that can help address the challenges our definition implies. The suggestions we provide range from empirical studies to multi-agent system theory.