Throughout the design cycle, visualization, whether a sketch scribbled on the back of a spare piece of paper or a fully detailed drawing, has been the mainstay of design: we need to see the product. One of the most important stages of the design cycle is the initial, or concept, stage and it is here that design variants occur in large numbers to be vetted quickly. At this initial stage the human element – the designer – is crucial to the success of the product. In this paper we describe an interactive environment for concept design which recognises the needs of the designer, not only to see the product and make rapid modifications, but also to monitor the progress of their design towards some preferred solution. This leads to the notion of a design parameter space, typically high-dimensional, which must also be visualized in addition to the product itself. Using a module developed for IRIS Explorer(TM) , design steering is presented as a navigation of this space in order to search...