The Application of Cognitive Psychology to CAD

The design of usable human-computer interfaces is one of the primary goals of the HCI specialist. To date however interest has focussed mainly on office or text based systems such as word processors or databases. Computer aided design (CAD) represents a major challenge to the human factors community to provide suitable input and expertise to an area where the users goals and requirements are cognitively distinct from more typical HCI. The present paper is based on psychological investigations of the engineering domain, involving an experimental comparison of designers using CAD and the more traditional drawing board. By employing protocol analytic techniques it is possible to shed light on the complex problem-solving nature of design and to demonstrate the crucial role of human factors in the development of interfaces which facilitate the designers in their task. A model of the cognition of design is proposed which indicates that available knowledge and guidelines alone are not sufficient to aid CAD developers and the distinct nature of the engineering designer's task merits specific attention.