Comparative analysis of high- and low-fidelity prototypes for more valid usability evaluations of mobile devices

Validation of low-fidelity prototyping test results is difficult because we cannot claim whether the results are the effect of the prototype itself or the essence of the design concept we try to evaluate. However, it will cost too much if we implement a fully functional prototype for more valid evaluation. In this research, we provide a qualitative and reflective analysis of usability evaluations of a text messaging functionality of a mobile phone by comparing three types of prototyping techniques---paper-based and computer-based and fully functional prototype. This analysis led us to realize how significantly the unique characteristics of each different prototype affect the usability evaluation in different ways. We identify what characteristics of each prototype causes the differences in finding usability problems, and then suggest key considerations for designing more valid low-fidelity prototypes based on this analysis.