The paper presents a discussion on the logic of the necessity for investigation into the area of physiological computing and reviews empirical work by some of the authors. In particular, the paper discusses the reliability of information that can be inferred from certain biological sensor data and ways in which positive benefits can be ensured or measured relating to the use of the feedback that can result from its use. One important and emerging application area for physiological feedback in interactive computing is in interactive art systems. In some respects, this application has been making strong progress for the particular reason that the interactive experience itself, rather than more abstract and problematic information handling, is at the core. Another interesting aspect of the applications in art is that they provide informal experimental investigations into these new forms of human‐computer interaction, and artists are already devising new applications and interfaces for physiological information. The paper describes an art work employing physiological feedback, including a discussion of how it was built and of the participating audience reactions when exhibited. q 2004 Elsevier B.V. All rights reserved.