Recent studies on the support of engineers during conceptual design resulted in a non-traditional type of Multi-Objective Problems (MOPs), namely concept-based ones. In concept-based MOPs the focus is on conceptual solutions that are represented by sets of particular solutions. This means that a concept has a one-to-many relation with the objective space. Such a set-based concept representation is most suitable for human-computer interaction. In concept-based MOPs concept-related preferences could be easily incorporated with or without range-related preferences. This paper provides an overview of studies on concept-based problems, which have been conducted at Tel-Aviv University, and suggests some future research directions.