According to Ferguson (1992 in Van Der Lugt, 2005: p 102-103), there are three kinds of sketches.
1. Thinking sketches refer to the designers making use of the drawing surface in support of their individual thinking processes.
2. Talking sketches refer to the designers making use of the shared drawing surface in support of the group discussion. Ferguson states: ‘…talking sketches, spontaneously draw during discussions with colleagues, will continue to be important in the process of going from vision to artifact. Such sketches make it easier to explain a technical point, because all parties in the discussion share a common graphical setting for the idea being debated’
3. Prescriptive sketches refer to the designers communicating design decisions to persons that are outside of the design process.
As Ullman (Ullman et al., 1990 in Van Der Lugt, 2005: p 103) states that sketches provide a means to store design ideas, so that they can be revisited at a later point in time. They will refer to this category of sketches as ’storing sketches.’ Storing sketcches refer to the designers using the drawing surface to archive design ideas for their own future reference. Storing sketches have much in common with perscriptive sketches. Van Der Lugt (2005: p 103) states “the storing sketch is intended for retaining information, whereas the perspective sketch is intended for communicating information.
Based on Van Der Lugt’s research (2005: p 119), the thinking sketch and the storing sketch can stimulate creativity, especially in the immediate individual idea generation process, and provide a more integated group process, by providing better access to the earlier ideas, especially in the shared parts of external memory.
Reference
Van Der Lugt, Remko. 2005. How sketching can affect the idea generation process in design group meetings: Design Studies. Vol 26 No.2 March 2005. Great Britain: Elsevier.