This paper introduces the Fundamental User Needs (FUN) Scales, tailored to measure need satisfaction and frustration in design-mediated interactions. The development and initial validation process included a preparation phase and four studies. Adopting a deductive approach, we generated a pool of 780 items and distilled them into the first version of the FUN Scales: a 52-item Need Satisfaction Scale and a 52-item Need Frustration Scale. Content validity was assessed by nine experts, leading to a refined second version. Exploratory and confirmatory factor analyses with 502 participants examined the scales’ factorial structure, reliability, and validity, resulting in a finalized version with 39 items per scale. Finally, we proposed two scoring approaches to facilitate scale application. The FUN Scales can serve as a robust diagnostic tool for quantifying the psychological impact of design and technology through the lens of need fulfillment, offering structure and inspiration for human-centered design research and practice.

We develop and test a model that suggests that expectations influence subjective usability and emotional experiences and, thereby, behavioral intentions to continue use and to recommend the service to others. A longitudinal study of 165 real-life users examined the proposed model in a proximity mobile payment domain at three time points: before use, after three weeks of use, and after six weeks of use. The results confirm the short-term influence of expectations on users’ evaluations of both usability and enjoyment of the service after three weeks of real-life use. Users’ evaluations of their experiences mediated the influence of expectations on behavioral intentions. However, after six weeks, users’ cumulative experiences of the mobile payment service had the strongest impact on their evaluations and the effect of pre-use expectations decreased. The research clarifies the role of expectations and highlights the importance of viewing expectations through a temporal perspective when evaluating user experience.