Noam Tractinsky

Research in the area of human-computer interaction (HCI) suggests that long or variable system delays lower user satisfaction with the interaction and the system in general. Designers cannot always control the delays in a system's responses (e.g. when accessing remote servers), but it is possible to design human-computer interactions so that the apparent duration of intervals will seem minimal. One way of achieving this goal is to structure tasks so that their apparent duration is reduced, partly by altering the number of choices and actions required for performing the task. Two laboratory experiments assessed the effects of the number of choices and the number of ballistic (simple) steps in a menu search on the apparent duration of the search. Results showed that the apparent duration increased with an increasing number of ballistic steps, while the number of choices had no effect on estimates. However, apparent durations were the shortest when the ratio of choices to ballistic steps was maximized. The implications of these findings for interface design are discussed.