Effects of Task Difficulty and Presentation Order in Subjective Usability Measurement

Abstract

The System Usability Scale (SUS) is a tool widely used in industry for measuring the usability of products and systems. Users are often asked to complete two or more tasks of varying complexity before evaluating a product using the SUS. However, task order effects may influence the overall usability rating of a product, but previous literature has not examined this issue. To test the effect of task order on the SUS, participants were asked to complete two tasks involving locating specific information on a college website. Participants completed an easy task and a hard task, and presentation of the tasks was randomized. Results showed that when participants completed the easy task first, they rated the overall usability of the website lower than when the hard task was presented first. This suggests that practitioners should be cautious when designing usability studies with tasks of varying difficulties.