PhD / In design literature, how designers think and how they design have been identified as a reflection of how they interact with their sketches. Sketching in architectural design is still a central concern which shapes our understanding of the design process and the development of new tools. Sketching not only serves as a visual aid to store and retrieve conceptualisations, but as a medium to facilitate more ideas, and to revise and refine these ideas. This thesis examined how mental imagery and sketching is used in designing by conducting a protocol analysis study with six expert architects. Each architect was required to think aloud and design under two different conditions: one in which s/he had access to sketching and one in which s/he was blindfolded (s/he did not have access to sketching). At the end of the blindfold condition the architects were required to quickly sketch what they held in their minds. The architects were able to come up with satisfying design solutions and some reported that using their imagery could be another way of designing. The resulting sketches were assessed by judges and were found to have no significant differences in overall quality. Expert architects were able to construct and maintain the design of a building without having access to sketching. The analysis of the blindfold and sketching design protocols did not demonstrate any differences in the quantity of cognitive actions in perceptual, conceptual, functional and evaluative categories. Each architect’s cognitive structure and designing behaviour in the blindfold activity mimicked her/his cognitive structure and designing behaviour in the sketching activity. The analysis of links between the design ideas demonstrated that architects’ performance in idea development was higher under the blindfold condition, compared to their sketching condition. It was also found that architects’ blindfold design performance was improved when they were more familiar with the site layout. These results imply that expert designers may not need sketching as a medium for their reflective conversation with the situation. This study indicates that constructing internal representations can be a strong tool for designing. Future studies may show that designers may not need sketching for the generation of certain designs during the early phases of conceptual designing.

PhD / In design literature, how designers think and how they design have been identified as a reflection of how they interact with their sketches. Sketching in architectural design is still a central concern which shapes our understanding of the design process and the development of new tools. Sketching not only serves as a visual aid to store and retrieve conceptualisations, but as a medium to facilitate more ideas, and to revise and refine these ideas. This thesis examined how mental imagery and sketching is used in designing by conducting a protocol analysis study with six expert architects. Each architect was required to think aloud and design under two different conditions: one in which s/he had access to sketching and one in which s/he was blindfolded (s/he did not have access to sketching). At the end of the blindfold condition the architects were required to quickly sketch what they held in their minds. The architects were able to come up with satisfying design solutions and some reported that using their imagery could be another way of designing. The resulting sketches were assessed by judges and were found to have no significant differences in overall quality. Expert architects were able to construct and maintain the design of a building without having access to sketching. The analysis of the blindfold and sketching design protocols did not demonstrate any differences in the quantity of cognitive actions in perceptual, conceptual, functional and evaluative categories. Each architect’s cognitive structure and designing behaviour in the blindfold activity mimicked her/his cognitive structure and designing behaviour in the sketching activity. The analysis of links between the design ideas demonstrated that architects’ performance in idea development was higher under the blindfold condition, compared to their sketching condition. It was also found that architects’ blindfold design performance was improved when they were more familiar with the site layout. These results imply that expert designers may not need sketching as a medium for their reflective conversation with the situation. This study indicates that constructing internal representations can be a strong tool for designing. Future studies may show that designers may not need sketching for the generation of certain designs during the early phases of conceptual designing.