During the last years engineers of the Munich Technical University and psychologists of the Dresden Technical University have investigated requirements for improved computer tools for designers. Prior studies of the early stages of the design process have shown that generating solutions is largely associated with the use of external representations such as sketches and physical models. In a postal survey 106 designers were consulted regarding the extent and the effects of using such external representations in the early stages of the design process. The results show the dominance of sketches as an external aid and the increasing use of CAD. The designers confirmed that external representations do not only serve as external information storages but as important external aids for, for example, solution development, testing and communication.
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