The strategic use of complex computer systems

Several studies show that despite experience, many users with basic command knowledge do not progress to an efficient use of complex computer applicat ions. These studies suggest that knowledge of tasks and knowledge of tools are insufficient to lead users to become efficient. To address this problem , we argue that users also need to learn strategies in the intermediate lay ers of knowledge lying between tasks and tools. These strategies are (a) ef ficient because they exploit specific powers of computers, (b) difficult to acquire because they are suggested by neither tasks nor tools, and (c) gen eral in nature having wide applicability. The above characteristics are fir st demonstrated in the context of aggregation strategies that exploit the i terative power of computers. A cognitive analysis of a real-world task reve als that even though such aggregation strategies can have large effects on task time, errors, and on the quality of the final product, they are not of ten used by even experienced users. We identify other strategies beyond agg regation that can be efficient and useful across computer applications and show how they were used to develop a new approach to training with promisin g results. We conclude by suggesting that a systematic analysis of strategi es in the intermediate layers of knowledge can lead not only to more effect ive ways to design training but also to more principled approaches to desig n systems. These advances should lead users to make more efficient use of c omplex computer systems.