Innovative applications are often complex systems. In designing this kind of application, usability, perceived usefulness and appropriateness of adaptation are the three most commonly assessed variables. However, in order to obtain a more engaging overall user experience, a good designer should perform proper formative and summative usability tests, based on the user's emotional level, which becomes a user-centered evaluation activity. Moreover, traditional methods are not ideal, as information about the user's emotional state should be captured in an implicit and transparent manner, in order to be non-invasive and more effective. Brain Computer Interface has recently witnessed an explosion of systems for studying human emotion by the acquisition and processing of physiological signals. The authors view Adaptive Virtual Environments, as one of the most representative examples of innovative applications, and also as elicitors of a complex user emotion synthesis. Therefore, in this paper the authors propose a user-centered approach to the design and support of the user experience through an adaptive virtual environment, via brain-computer interface. Firstly, the authors focus on the design of an engaging overall experience for potential users, by exploiting their emotional level as a powerful engine in the interaction experience. Secondly, the author work to enhance the user experience by dynamically adapting the interaction to the user's emotional state, so that there will be a more immersive and satisfying interaction.
