The user would like the computer to do the tedious parts of the task. Programming all parts of the task might be expensive or impossible. Ensure that the computer adds value to the performance of the user's task. Look for places where the computer can go beyond merely being a storage device, and can provide summary information, computation, automatic placement, analysis, and arranging. The user gets confused when information scrolls past too quickly to read.
Users like to feel in charge of what they are doing and the pace of their work.
Let the user control navigation. Users should be able to move the focus of attention at their own pace. Zones of Similar Persistence lets the user focus on what has changed since they last looked at the screen. User Controls Navigation restricts what will happen without user involvement. Modelessness prevents context-dependent situations.