Usability testing is an important part of product design that offers developers insight into a product’s ability to help users achieve their goals. Despite the usefulness of usability testing, human usability evaluations are costly and time-intensive processes. Developing methods to reduce the time and costs of usability evaluations is important for organizations to improve the usability of their products without expensive investments. One prospective solution to this is the application of facial emotion recognition to automate the collection of qualitative metrics normally identified by human usability evaluators. In this paper, facial emotion recognition (FER) was applied to mock usability recordings to evaluate how well FER could parse moments of emotional significance. To determine the accuracy of FER in this context, a FER Python library created by Justin Shenk was compared with data tags produced by human reporters. This study found that the facial emotion recognizer could only match its emotion recognition output with less than 40% of the human-reported emotion timestamps and less than 78% of the emotion data tags were recognized at all. The current lack of consistency with the human reported emotions found in this thesis makes it difficult to recommend using FER for parsing moments of semantic significance over conventional human usability evaluators.

Syftet med den här uppsatsen var att belysa frågan om hur många användare det behövdes för att uppnå en viss mättnad i en användbarhetsutvärdering för en specifik flash-applikation kallad My Garden. De aspekter som låg till grund för denna uppsats var brytpunkten i ökningen av unika fynd i korrelation med höga procentsatser. Med hjälp av den formativa utvärderingen och analysen av denna gick det sedan att ta reda på vilka problem (så kallade fynd) som upplevdes av användarna i gränssnittet. Resultatet av analysen resulterade i 95 unika fynd i tio användbarhetsutvärderingar. Resultatet visade följaktligen att för denna sorts utvärdering behövdes sju användare för att uppnå 93 % av alla unika fynd som hittades och därmed uppnå en slags mättnad i avklingandet av hittade unika fynd. / The purpose of this report was to highlight the issue of how many people are needed to reach a certain level of saturation in a usability evaluation of a specific flash application called My Garden. The aspects that formed the basis of this study were the breakpoint in the growth of unique findings in correlation with high percentages. The help of the formative evaluation and the analysis made it possible to find out what kind of problems (so called findings) the users experienced within the interface. The results of the analysis resulted in 95 unique findings in ten usability evaluations. The results showed consequently that for this kind of evaluation seven users where needed to reach 93 % of all unique findings and thereby achieve a kind of saturation in the unwinding of the findings of unique findings.