The Importance of Human Mental Workload in Web Design

The focus of this study is the introduction of the construct of Human Mental Workload (HMW) in Web design, aimed at supporting current interaction design practices. An experiment has been conducted using the original Wikipedia and Google web-interfaces, and using two slightly different versions. Three subjective psychological mental workload assessment techniques (NASA-TLX, Workload Profile and SWAT) with a well-established assessments usability tool (SUS) have been adopted. T-tests have been performed to study the statistical significance of the original and modified web-pages, in terms of workload required by typical tasks and perceived usability. Preliminary results show that, in one ideal case, increments of usability correspond to decrements of generated workload, confirming the negative impact of the structural changes on the interface. In another case, changes are significant in terms of usability but not in terms of generated workloads, thus raising research questions and underlying the importance of Human Mental Workload in Interaction Design.