The Influence of Usability on Cognitive Load and Eye-movements

Abstract: With its increased availability on the commercial market, eye-tracking has become a widely accessible system for analysing eye-movements. This has opened up new possibilities in evaluation of usability in human-computer interaction, which has had a history of being expensive, time-consuming and often performed based on poorly documented standards and objectives. Previous research has indicated the ability of eye-tracking to evaluate a users’ cognitive load based on eye-movements. This research suggests that there exists a possibility to utilise this technology in evaluation of usability. In this master thesis, an experiment involving 30 participants was conducted to examine the influence of usability on cognitive load and eye-movements. This was done by letting the participants interact with three interface-prototypes. Two of which violated some fundamental design principles, whilst the remaining one was designed according to these principles and acted as a point of reference. The hypothesis was that the flawed designs would result in interfaces of poor usability, contributing to a higher cognitive load during usage. This would in turn be objectively reflected in some specific metrics derived from the recorded eye-tracking data. While no differences in perceived cognitive load was found, one of the flawed prototypes, which intentionally disregarded the principles of proximity and functional grouping, was distinguished from the two others based upon three specific eye-tracking metrics. Therefore, it is suggested that eye-tracking data has the potential to objectively reflect the usability of an interface. However, further research is required to investigate under what circumstances our results generalise to other designs.