Abstract
As mobile loyalty programs become integral to customer engagement tactics in retail, comprehending user experience (UX) across both functional and emotional dimensions is increasingly essential. This study provides a multimethod approach to assess mobile app usability in Slovakia. First, a quantitative survey of 1386 respondents revealed that loyalty programs, particularly those included in mobile apps, are a crucial determinant in consumers' selection of grocery merchants. Three leading grocery retailers were selected for further investigation. Then, a focused quantitative survey of 863 active users of the selected loyalty apps evaluated user satisfaction, usage patterns, and perceived usability using the System Usability Scale (SUS), and Net Promoter Score (NPS). Finally, biometric and neurophysiological data were collected from 44 individuals using EEG and eye tracking while engaged in task-based navigation in a laboratory setting. We documented UX-related indicators, including visual attention, frustration, and engagement, during real-time interaction. The results indicate considerable differences in user satisfaction and neurophysiological reactions among apps. The highest-rated app on declarative measures also exhibited more efficient visual navigation; however, neurophysiological data revealed instances of frustration even in highly rated interfaces. The observed divergence between self-reported evaluations and neurophysiological indicators demonstrates that declarative and physiological measures capture complementary rather than interchangeable dimensions of UX. The findings have implications for the design and evaluation of mobile loyalty apps and support the integration of neurophysiological tools with established declarative measures in digital customer experience research. We documented critical UX metrics, including visual attention, irritation, engagement, and cognitive load, in real time.