Quantitative Usability Testing in User-Centered Product Development with Mobile Eye Tracking

Abstract

The usability assessment of tangible products holds manifold challenges in identifying the sources of usability problems and quantifying the evaluation of user-product interactions. In this field, the use of modern mobile eye tracking systems show great potential, as they are capable of non-invasively capturing the user’s field of vision, including the gaze point in almost any real-word setting. With the eye movements captured, the eye tracking data provides information, which offers an insight into the user’s intentions and struggles. However, the prospects of mobile eye tracking for usability assessments of tangible products are not well studied yet, and there is a lack of methods supporting the analysis of the resulting eye tracking data. Therefore, the goal of this thesis is to evaluate mobile eye tracking in usability assessments of tangible products over the conventional third-person view, and to develop methodological supports for the data analysis. A comparison study shows that the mobile eye tracking perspective leads to a more detailed description of the scene and a better explanation for the causes of usability problems, when compared to the third-person perspective. To facilitate the analysis of eye tracking data, three analysis methods have been developed. The Target-Based Analysis is a coding scheme for manual analysis, whereas the Scrutinizing algorithm and the Hand-Gaze Distance approach are semi-automated supports, detecting interruptions of the usage flow, considering fixation durations, saccade amplitudes and hand movements. The evaluation of the three methods shows that the Target-Based Analysis is applicable to a broad variety of applications, however, it is time-consuming. Both, the Scrutinizing algorithm and the Hand-Gaze Distance approach are able to reduce the manual effort and to identify usability problems, however, they are less accurate. The evidence-based description of the detected usability problems, derived from the mobile eye tracking data, are quickly understood, accepted, and foster a solution-oriented discussion, when presented to others. Overall, the application of mobile eye tracking in usability testing is vital, as it allows for a fine-granular and a quantifiable evaluation of user-product interactions. The three developed methods are of benefit for the analyst and enable the interpretation of eye tracking data in a more structured and partly automated way. In the future, with analysis methods developed further, mobile eye tracking is suitable to become an important element of usability assessments of tangible products.