Remembering while mousing: the cognitive costs of mouse clicks

Thinking harder, attending more carefully, remembering more or for longer periods are activities that all contribute to the mental overheads that may have to be met when working with computer displays. One way of measuring these cognitive costs is by providing users with tools (e.g. memory aids) and then seeing how features of the interface influence the way people use these tools. In some respects this is like providing a hiker with a walking stick; the stick may not be used much until the going gets tough. This technique was developed in order to explore the memory load people experienced when working with a document on a computer screen. The practical issues concern saving space on the screen by removing some of the information that readers will need only intermittently but leaving the material accessible, just a mouse click away from the current screen display. The scientific issues concern the memory processes involved when people are working with indexes or menus that have to be summoned into view by clicking a button on the screen.