Externalisation in design: impact of different tools on designers' activities and on the assessment of final design

This study contributes to a better understanding of how the use of different tools influences both the design process and the way that final designs are assessed. Unlike previous research comparing computer aided design (CAD) and freehand sketching, we compared CAD and manual modelling. CAD systems and manual modelling both tend to be used after the early design stage, which is mainly involves sketching. Our study would therefore be useful for determining which of the two is more appropriate, depending on the designer's priorities and the intended purpose of the object being developed. Our study was conducted in two phases. First the activities of 20 designers were recorded in two different experimental conditions: 1) using a CAD system 2) using manual modelling. Secondly, 20 other participants (judges) were asked to assess the end results of these activities. According to the experimental condition, we observed differences in both the design activities and the assessments of the final designs. More specifically, items designed using a CAD system were scored higher on aesthetics, originality and marketing. However, no difference was observed for the functionality criterion. Use of a CAD system would appear to be most appropriate for highlighting aesthetic and marketing features, but manual modelling remains a suitable tool for designing functional objects.