This paper presents a model of the way that designers move between situations when interpreting during design activity. Three hypotheses are presented that arise from this model: that designers change their situation during interpretation, that small changes in a source can lead to large changes in the representation, and that changes to the situation have their origins in the experience of the designer. The paper demonstrates how this internal movement between situations can be computationally implemented using three examples. The systems implemented demonstrate the way that interpretation can lead to changes in the situation and present an example of how the changes to a designer's situation can be guided by past experiences.
Keywords: situated design, computational modelling, interpretationDesigners frequently change their notion of what they are doing during design, but how this happens has not yet been adequately explained, nor has it been modelled computationally. It has long been recognised that the expectations held by a designer (the way that they 'see ') have an effect upon their future design moves (Schon & Wiggins, 1992). This work is concerned with the question of when do a designer's expectations change and why do they change to one set of expectations and not another? It is an enquiry into the relationship between experience and expectation as observed in a design conversation.Designers' notions of what they are doing change during design activity, and through thinkaloud studies and video recordings it is possible to observe, to some degree, what their notions are changing from and to (Fish & Scrivener, 1990;Gross & Do, 2000;Suwa & Tversky, 1997). The motivation for this work is to move beyond observation and to posit the Page 2 of 30 cognitive processes that relate knowledge from experience to the changing conception of a design task, with the aim of making computational models of design more 'designerly' (Cross, 1982).To place the focus upon the cognitive processes of the designer, design will be conceived here as a sequence of actions by a designer, where these actions are distinguishable activities over time that take place within a situation (Gero, 1998). The term situation refers here to a designer's internal notion of the world at a particular time, their co-ordinated expectations (Clancey, 1997). This definition of situation in design is related to terms that emphasise aspects of the same notion: the current internal context (Kennedy & Shapiro, 2004), the current epistemic frame (Shaffer et al., 2009) and the current ecology of mind (Gabora, Rosch, & Aerts, 2008) 1 . The situation refers to the parts of grounded knowledge (Barsalou, 2007) that come from experience within the world and that are being used to understand the world at this current moment and in this current experience.The paper first describes a model linking the situation of a designer (and their expectations within this situation) to the cognitive process of interpretation -something that occurs frequently during...