Abstract
The paper presents an extensive testing campaign aimed at revealing the factors that mostly influence ideation performance within the Product Planning phase of engineering design. Tailored techniques mirror Brainstorming principles and differ according to the ways analogical thinking is stimulated. By comparing different conditions in ideation sessions, the results remark the relevance of submitting manifold formalised stimuli, at least for what concerns Engineering students. The effect of teamwork is arguable, as individuals working separately are capable of producing larger numbers of ideas.