Evaluating Prototype Fidelity: Impacts on Cognitive Workload and Mental-Model Alignment in Flight-Booking Interfaces

Abstract

Early-stage prototyping is essential for translating user requirements to functional design concepts. However, empirical evidence that investigates how prototype fidelity impacts cognitive workload and mental-model alignment within multi-step tasks is limited. This study examines three levels of fidelity (low-fidelity paper sketches, medium-fidelity clickable wireframes and high-fidelity static HTML pages) in a multi-step flight-booking scenario. Participants in this study included 25 undergraduate students who completed the moderate-complexity task workflow using a counterbalanced within-subjects design. The NASA-TLX was used to measure perceived cognitive workload and mental-model alignment was evaluated using a self-report Likert-scale questionnaire. Thus, the following results demonstrated a significant reduction in cognitive workload and increase in mental-model alignment with increase in fidelity. Further task performance analysis indicated that completion times were faster for medium-fidelity wireframes than for other conditions. Therefore, these findings present empirical guidance for selection of prototype fidelity which further demonstrates that medium-fidelity wireframes provide considerable cognitive and usability benefits along with reduced resources.