The main behavioural characteristics of the early design stage are that
designers move freely between various levels of detail and different cognitive
strategies; this is the central tenet of this research. The interplay between the
role of sketching and mental imagery during the design process is somewhat
mysterious.
It is assumed, but not known, how externalisation assists the imagery
process and vice versa. In an attempt to demystify this interplay, this paper examines
observable behaviour associated with the act of sketching and using mental
imagery. It reviews established protocol analytical methods based on two criteria:
cognitive strategies and ability to be applied in different design domains. Also, it
evaluates the appropriacy of seminal coding schemes for the analysis of mental
imagery to better understand moments of insight (idea generation). It concludes
that established coding schemes are inadequate methods when used to facilitate
analysis of cognitive strategies
