DISPLAY-BASED ACTION AT THE USER INTERFACE

This paper examines the hypothesis that information flow, from device to user, is a vital part of skilled activity in human-computer interaction. Two studies are reported. The first study questions users of keyboard-driven word processors about the effects of cursor-movement, finding and word-deletion commands in various contexts. The second study questions users of the Apple Macintosh-based systems, MacWrite and Microsoft Word, about the behaviour of the menu-driven find command. In both studies it is discovered that users often do not know the precise effects of frequently-used actions, such as the final position of the cursor, even though these effects are vital for future planning. It is concluded that even experienced users must acquire the information they need from the device's display during interactions, and that they do not necessarily remember regular details that are available in this way. This conclusion conflicts with those current models of user psychology that assume routine skill relies on complete mental specifications of methods for performing tasks. © 1991 Academic Press Limited.