Understanding affective reactions is essential to improve human-computer interaction and the design of systems. This assessment of user motivational state can be used to evaluate interface design or to define interactive feedback or adaptation in systems.
Thus the field of affective computing investigates and integrates many perspectives from psychology, neurophysiology and computer science. In the domain of e-learning and e-commerce those techniques are being used informally to observe interactions during the design of systems, but more systematic methods are necessary to efficiently highlight important aspects of the interaction, or more importantly in order to design adaptive interactions.