Subliminal User Interfaces - Computer Applications as Agents of the Mind Alvaro Cassinelli — University of Tokyo, Ishikawa Hashimoto Laboratory, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan — alvaro@k2.t.u-tokyo.ac.jp Originally written circa 2001 as an unpublished research proposal. This version has been lightly formatted and edited for online publication. Introduction From graphical interfaces to perceptual user interfaces (PUI) Perceptual Human Interfaces (PUIs) may well be the future of graphical user interfaces if they succeed in making communication with machines natural enough. However, I believe there is more to human-computer interaction than simply giving computers the capacity to understand—or reply by mimicking—a human face, a gesture, or even complex attitudes and other less codified forms of human communication. My guess is that, sooner or later, there will be a paradigm shift in how we understand human-computer interaction: in the future, it may not rely on...