Teaching Cognitive Load Analysis in UX Courses Using NASA-TLX and Task Performance Metrics: A Laboratory Scenario
Karol Łazaruk, Piotr Tokarski, Sergio Luján-Mora
Proceedings of the 18th International Conference on Education and New Learning Technologies (Edulearn 2026), Palma de Mallorca (Spain), June 29-July 1 2026.
(EDULEARN'26b)
Congreso internacional / International conference
Resumen
Cognitive load is a critical issue in the context of user experience (UX) in graphic interface design. This aspect concerns the level of effort that a user needs to put into performing a specific task within the interface. In teaching practice, especially in the academic education of students of UX and interface design, the subject is often reduced to theoretical topics or even completely omitted. Students typically do not have the opportunity to explore the practical analysis of cognitive load. Cognitive effort can be measured using subjective evaluation tools, such as the NASA Task Load Index (NASA-TLX) survey method, which allows for the assessment of workload in six dimensions. However, this approach is based only on the subjective experiences of users and may not be sufficient, as the perception of task difficulty does not always correspond to the actual level of cognitive effort during interaction with the system. An alternative is to analyze objective metrics related to task performance, such as task completion time or number of errors made. Combining both subjective and objective methods within a single analysis can help to achieve a more complete understanding of cognitive load and identify interface elements that cause difficulty in use. At the same time, this approach can be a valuable teaching tool in the education of UX students, allowing them to gain practical experience in the process of designing and analyzing usability studies. The aim of this work is to conduct a cognitive load analysis based on a method using the subjective NASA-TLX index and objective data on task performance in mobile application interfaces. An additional goal is to propose a comprehensive laboratory class scenario that can be implemented in a study program related to UX and interface design. The study was conducted on 20 students who were familiarized with the interface of two selected mobile applications and then performed five tasks in each of them. During the experiment, task performance metrics were measured: task completion time, task success, and number of errors made. After the session, participants completed NASA-TLX questionnaires. Based on the collected results, subjectively assessed cognitive load was compared with objective performance metrics in individual tasks. The results of the analysis reveal a relationship between subjectively assessed cognitive load and performance metrics. The application that required more time to complete tasks and resulted in a higher number of errors was also rated by participants as more cognitively demanding on the NASA-TLX scale. From a teaching perspective, the experiment provided a better understanding of the relationship between subjective overall workload assessment and objective performance indicators. The incorporation of the proposed laboratory scenario opens up the possibility of introducing students to the basics of cognitive workload analysis in UX research.