What do strokes teach us about collaborative design ?

Understanding collaborative design goes far beyond analyzing group dynamics, tasks allocations or negotiation during decision-making processes. In this paper, we focused on the collaborative sketching process, during which the intentions of designers are supported by their sketches and by specific strokes.Twelve professional designers attended an experimental design session, where they were asked to express, share, capture or interpret sketches. A qualitative and quantitative fine-grained analysis of strokes teach us (i) how designers tend to deal with representations that are not theirs; (ii) what main graphical key-features constitute the inner nature of the shared information and (iii) how and when can this graphic essence be shared with collaborators.