An experimental investigation of the interactive effects of interface style, instructions, and task familiarity on user performance

Norman proposed a model describing the sequence of user activities involved in human-computer interaction. Through this model, Norman provides a rationale for why direct-manipulation interfaces may be preferred to other design alternatives. Based on action identification theory we developed several hypotheses about the operations of Norman's model and tested them in a laboratory experiment. The results show that users of a direct-manipulation interface and a menu-based interface did not differ in the total amount of time used to perform a task. However, with the direct-manipulation interface, more time is devoted to performing motor actions , but this is offset by shorter nonmotor time . Furthermore, there are significant interactions between task familiarity, instructions, and the type of interface, indicating that Norman's model may not hold under all conditions.