Artifacts, including Representations, Develop over Time Making Representations

based on use. Contrary to what one might expect, change often implies that specific representational artifacts lose some of their representational aspects in order to increase the effectiveness of their use. Consider for example the case of numerals. Originally, their representational aspects were much more obvious than today. The numbers two and three, for example, were represented by an equal number of pellets or marks. This simple relation between the number sign and what was represented was later abandoned in favor of more abstract forms found to be more effective in use, first with the Roman and later with the Arabic numerals. In fact, most representational artifacts work so well not because they mirror that which is represented, but because they do not, that is, the representation captures a few intentionally selected qualities of that which is represented and nothing more. 1 Thus we do not want the receiver of a herd of cattle to look at the size of the accompanying pellets to judge the supposed weight of the individual animals or the like, but just to check that the numbers match. The pellets work because both sender and receiver know this—they share a practice of using pellets to stand for cattle. However, pellets and other representational artifacts do have such nonrepresentational aspects as size simply because they are physical artifacts. These additional qualities open up Ar tifacts, when used in the process of cooperative design, allow end users to simulate future work by creating hands-on exploration of emerging designs. They act as open-ended representations that call for the u s e r ' s a c t i v e c o o p e r a t i o n to function in design. Work 1 The existence of representations at all is an indication of this: We use representations because they are, for some reason, better suited for the work in question than that which is represented. Obviously " the represented " is closer to itself than a representation, therefore, some of the difference from the represented is what makes the representation better suited for the specific use in question.