Learning From Experienced User in Real Life.

Paper in proceeding, 2007

User-centered design (UCD) has become a popular design philosophy and process in recent years. According to this design philosophy, end users’ needs, expectations and limitations when interacting with interfaces or systems are also taken into consideration at each stage of the design process. At the practical usability evaluation stage, how to select test subjects as end users always concerns the reliability of the evaluation results. In a small pilot study, three usability evaluation methods were employed to evaluate the experienced users’ performance on a simple interface, the interface of a Whirlpool microwave oven in a lunchroom at a working-place. The purpose of the study was to investigate how well experienced users handled the interface by performing casual tasks. The aim was to obtain proposals from the evaluation results for future redesign issues. Three usability evaluation methods were used in the study; i.e. Heuristic evaluation (HE), Thinking-Aloud method (TA), and Co-discovery method (CO). Seven typical task scenarios which reflect the typical main functions in practical daily usage of a microwave oven were selected for the evaluation. Altogether sixteen staff members of the working-place participated in the empirical tests. The results from the three methods were compared to each other, in terms of prediction on problem severity, task completion time, and satisfaction. Subjective assessment on task scenarios was also made in the end of each evaluation session. Statistical T-test and Mann-Whitney test were used in the analysis of the results. The results showed that all the test subjects failed in completing several task scenarios, which promotes designers and human factors engineers to reconsider the practical usage and efficiency of multi-functionality on product design and users’ expectations on interface design. In addition, the results also implied some interesting findings and differences among the three evaluation methods, which provide useful information for selecting usability evaluation methods.