An experimental investigation of interface design alternatives: icon vs. text and direct manipulation vs. menus

Abstract

This paper reports on two experiments which examine the effects of iconic and direct manipulation interfaces on the performance of casual users using an electronic mail system. There are two key aspects to these experiments. First, they have been carefully designed to separate the effect of iconic representation from that of direct manipulation in order to examine the independent effect of each as well as their joint effect. Second, subjects performed the same experimental task three different times over 1 week, thus allowing for the effects of icons and direct manipulation interfaces to be assessed over repeated trials. Each experiment measured time taken and errors made in task completion as dependent variables. Results indicate that there were no advantages associated with iconic representations compared to text-based representations of actions and objects. Subjects working with direct manipulation interfaces completed the task faster than those with menu-based interfaces. However, this difference in time was not significant when the task was repeated for a third time, indicating that the benefits to direct manipulation might diminish after a learning period. No interface was better than others in terms of reducing error rates when interacting with the computer system.