User Interface Development for Interactive Multiobjective Optimization Software Suvi Luoma Interactive multiobjective optimization (IMO) methods for multiple criteria decision making cannot be properly utilized by the real decision makers without user-friendly software implementations. Hence, there is a need for developing intuitive and easy-to-use user interfaces for these systems. Systems for multiple criteria decision making can be characterized as complex systems, meaning that the amount of information is large and the problems are open-ended and cognitively burdensome to solve. Well-reasoned representation and interaction techniques accelerate rapid insight into complex data, and thus facilitate the analytical reasoning process being as an essential part of the decision making process. In my presentation, I will shortly introduce the ongoing software development projects within the optimization group especially from a user interface designer's point of view. The implementations of the new IMO methods, 'Pareto navigator' and 'Nautilus', are used as examples to demonstrate concrete challenges of user interface design. For these methods, the early sketching stage is shortly described, and future research directions are discussed. One of the objectives of my research is to apply techniques and theories provided by the somewhat new research field of 'visual analytics', as well as theories based on cognitive sciences and human-computer interaction.