This paper describes a research approach to the experimental study of emotional experiences and their connections to other components of user experience in human-technology interaction. We present a model of user experience that integrates interaction characteristics, instrumental and non-instrumental quality perceptions, emotional user reactions and overall judgments of system quality. An experiment is reported to illustrate the application of our approach. System properties of an interactive prototype were varied to produce versions of different usability and aesthetics which in turn led to different perceptions of instrumental and non-instrumental qualities. The results indicate that both quality aspects significantly influence emotional reactions with respect to subjective feelings, facial expressions and physiological responses. These findings are consistent with the users' overall judgments of the systems and show that the perception of both, instrumental and non-instrumental qualities influences the appraisal of interactive systems.