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.

Abstract (Swedish)

Med sin ökade tillgänglighet på den kommersiella marknaden har eye-tracking blivit ett allmänt tillgängligt system för att analysera ögonrörelser. Detta har öppnat upp för nya möjligheter för utvärdering av usability inom humancomputer
interaction, som tidigare har varit dyrt, tidskrävande och ofta utfört baserat på dåligt dokumenterade standarder och mål.
Tidigare forskning har visat att eye-tracking har förmåga att utvärdera användarnas kognitiva belastning baserat på ögonrörelser. Denna forskning tyder på att det finns en möjlighet att använda detta system för utvärdering av usability. I detta examensarbete genomfördes ett experiment med 30 deltagare för att undersöka hur usability påverkar kognitiv belastning och ögonrörelser. Detta gjordes genom att låta deltagarna interagera med tre gränssnittsprototyper. Två av dessa prototyper hade avsiktliga brister baserat på fundamentala designprinciper medan den återstående följde dessa principer och användes som referens.
Hypotesen var att de bristfälliga designerna skulle resultera i gränssnitt med dålig usability, vilket skulle bidra till en ökad kognitiv belastning under användning. Detta skulle i sin tur reflekteras objektivt i vissa specifika mätvärden härledda från inspelad data från eye-tracking.
Trots att inga skillnader i upplevd kognitiv belastning identifierades kunde den bristfälliga prototypen, som avsiktligt bortsåg från principerna om närhet och funktionell gruppering, särskiljas från de två andra baserat på tre specifika mätvärden. Därför föreslås det att eye-tracking har potentialen att objektivt reflektera usability hos ett gränssnitt. Dock krävs mer forskning för att undersöka under vilka förutsättningar dessa resultat är giltiga.

Popular Abstract

Eye-tracking - the Future of Usability Evaluation?

The movements of the eyes can tell a lot about our subconscious processing. With eye-tracking, interaction-designers have a powerful tool with which to unlock the secrets of the human mind and its cognitive processes. These processes are fundamental to the function of any human-computer interface and vital for overall usability. The results from this study show that eye-tracking can be used to distinguish between interfaces of varying design quality. Eye-tracking therefore has the potential to revolutionise the field of interface-design.
A usable product should guide the user during interaction and be designed in a way that hinders the user from committing mistakes. With the ongoing digitisation of all aspects of society, the importance of good interface-design can not be overstated. However, measuring usability is a complicated, timeconsuming and often expensive process focused around subjective experiences.
Since subjective experiences rarely tells the whole truth, this field is in need of a renaissance. Eye-tracking has the potential to lead this renaissance. By tracking the movements of the eyes, this technology supplies valuable information about how a interface is perceived and interpreted. This allows for instantaneous and objective analysis of the interaction that can offer easy to perform usability evaluation.
In this study, eye-tracking was used during 30 participants’ interaction with three interface-prototypes of varying usability. Here, two of the prototypes violated established design principles whilst the remaining one acted as a point of reference. Using metrics derived from the eye-tracking data one of the flawed interface-prototypes was distinguished from the reference. This finding is especially interesting since an subjective assessment of the participants’ experience showed no perceived difference in interface-quality between the flawed interface and the reference. This reinforces the capability of eye-tracking in capturing subconscious processes.
This study has only scratched the surface of the potential of eye-tracking. The findings encourage further, more comprehensive, research within this field. The method used also show that eye-tracking can be implemented and
adjusted to fit any environment seamlessly. This offers a huge opportunity for a wide variety of real-life applications.
If the eyes are truly the mirrors of the soul, eye-tracking could lead a renaissance in interface-design with the potential to revolutionise the entire field of usability evaluation

• author: Mauritsson, Max and Jigsved, Anton
• supervisor: Johanna Persson; Marcus Nyström
• organization: Ergonomics and Aerosol Technology
• course: MAMM01 20211
• year: 2021
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Eyetracking, Eye-tracking, Cognitive load, CLT, Usability, Eye-movements
• language: English
• id: 9050739
• date added to LUP: 2021-06-09 11:28:00
• date last changed: 2021-06-09 11:28:00