Brainstorming is a method for creative problem solving in the design studio learning. In brainstorming, linking ideas is regarded as searching design in design space which is constructed by a graph-like knowledge structure between participantsi knowledge. Idea Map provides the potential knowledge representation for representing such design space. This research conducts an experiment to understand how novice designers generate conceptual designs through an idea map. Finally, a preliminary computational mechanism for controlling an effective map size to develop conceptual designs is proposed.