This paper presents a case study of end users and designers and how they perceive different mobile shopping app user interfaces (UIs). This paper aims to explore the UI preference differences between users and designers and elucidate specified UI attributes that are reflective of user preferences. This paper contains three procedures: 1) eliciting users' and designers' UI perceptual similarity by sorting to identify UI perceptual similarity space; 2) eliciting users' and designers' overall preferences by rating, which displays the preference dimensions; and 3) eliciting users' and designers' idiosyncratic perceptions by using the repertory grid technique (RGT), which indicates the UI perceptual differences between the users and the designers. The specified inter-group perceptual differences were detected by comparing RGT-elicited perceptions. The UI design features were explored, which influenced the designers' and users' subjective evaluations. The results showed four typical mobile shopping app UIs, and the distribution of ideal preference UIs for users and designers was evaluated. Through the experiments, rich qualitative insights were quantified, and valuable information from the participants was obtained. The specified design attributes of UI on the mobile shopping app, which improved user satisfaction, were found out. Moreover, those attributes will help designers know which important attributes should be noted.
