Katrien De Moor

Factors Influencing Quality of Experience

In this chapter different factors that may influence Quality of Experience (QoE) in the context of media consumption, networked services, and other electronic communication services and applications, are discussed. QoE can be subject to a range of complex and strongly interrelated factors, falling into three categories: human, system and context influence factors (IFs). With respect to Human IFs, we discuss variant and stable factors that may potentially bear an influence on QoE, either for low-level (bottom-up) or higher-level (top-down) cognitive processing. System IFs are classified into four distinct categories, namely content-, media-, network- and device-related IFs. Finally, the broad category of possible Context IFs is decomposed into factors linked to the physical, temporal, social, economic, task and technical information context. The overview given here illustrates the complexity of QoE and the broad range of aspects that potentially have a major influence on it.

User-driven innovation? Challenges of user involvement in future technology analysis

The shift from the traditional push towards more user-driven innovation strategies in the information and communications technologies domain has urged companies to place the user at the core of their innovation process in a more systematic way. In this paper we reflect on the implications of this new innovation context for traditional product development processes. Given these implications, two challenges are discussed that are crucial to true user-driven innovation, i.e. the challenge of continuously involving the user and the need for tools to facilitate the integration of knowledge into the increasingly interdisciplinary development process. Drawing on our own experiences in the interdisciplinary Research On Mobile Applications and Services (ROMAS) project, which focused on future mobile applications in a living lab setting, we illustrate how the two challenges can be tackled. Copyright , Beech Tree Publishing.

Fanboys, competers, escapists and time-killers: a typology based on gamers' motivations for playing video games

In this paper, the different general motivations of gamers for playing video games are explored. Surprisingly, to date little research has been devoted to the characterization of the gamer, based on general game motivations. By means of an online survey, we questioned 2985 Flemish gamers on 11 general game motivations. K-means clustering was used to distinguish four distinctive gamer profiles: the overall convinced gamer, the convinced competitive gamer, the escapist gamer and the pass-time gamer.

Quality of Experience Versus User Experience

The current chapter discusses the concepts Quality of Experience and User Experience. As Quality of Experience is introduced in the previous chapter, this chapter starts with an introduction to the User Experience concept at the level of theory and practice. First its origins, definitions, and key attributes are discussed. This is followed by an overview of methods and approaches to evaluate User Experience in practice. Thereupon, we discuss both concepts in comparison. While a number of similarities are identified, these are exceeded by the number of differences, which are situated at the theoretical-conceptual level and the methodological-practical level. It is concluded that User Experience is the more mature concept, both at the level of theory and practice. Thus the literature within the User Experience domain can be of great value for the Quality of Experience-community, especially if the latter intends to really put the recently proposed more holistic definition of Quality of Experience into practice.

Content categorization based on implicit and explicit user feedback: Combining self-reports with EEG emotional state analysis

We present a study that combines and compares explicit (questionnaire-generated) and implicit (EEG-based) feedback from test subjects on perceptual dimensions of different types of audiovisual content. We found significant differences in importance and evaluation of perceptual-, viewer-and clip-related dimensions across a limited set of contents. The results suggest that additional bio-feedback data can help to increase validity and robustness of user feedback in Quality of Experience (QoE) and content categorization research.

Chamber QoE: a multi-instrumental approach to explore affective aspects in relation to quality of experience

Evaluating (audio)visual quality and Quality of Experience (QoE) from the user’s perspective, has become a key element in optimizing users’ experiences and their quality. Traditionally, the focus lies on how multi-level quality features are perceived by a human user. The interest has however gradually expanded towards human cognitive, affective and behavioral processes that may impact on, be an element of, or be influenced by QoE, and which have been underinvestigated so far. In addition, there is a major discrepancy between the new, broadly supported and more holistic conceptualization of QoE proposed by Le Callet et al. (2012) and traditional, standardized QoE assessment. This paper explores ways to tackle this discrepancy by means of a multi-instrumental approach. More concretely, it presents results from a lab study on video quality (N=27), aimed at going beyond the dominant QoE assessment paradigm and at exploring affective aspects in relation to QoE and in relation to perceived overall quality. Four types of data were collected: ‘traditional’ QoE self-report measures were complemented with ‘alternative’, emotional state- and user engagement-related self-report measures to evaluate QoE. In addition, we collected EEG (physiological) data, gazetracking data and facial expressions (behavioral) data. The video samples used in test were longer in duration than is common in standard tests allowing us to study e.g. more realistic experience and deeper user engagement. Our findings support the claim that the traditional QoE measures need to be reconsidered and extended with additional, affective staterelated measures.

Patient responsibility reallocation: a user-centered approach to support nurses' handling of nurse calls

A central part of nurses’ work at a hospital department is to respond to nurse calls issued by patients in need of assistance. In the highly dynamic work environment, where nurses need to continuously shift focus and handle interruptions, managing nurse calls presents a challenge. Previous studies of nurses’ use of a wireless nurse call system deployed at a major Norwegian university hospital, point to how nurses apply various strategies to handle nurse calls efficiently. These strategies involve a high degree of collaboration and coordination among nurses. By means of a user-centered approach, a system prototype has been designed. This system aims to support nurses in their continuous reallocation of patient responsibilities, through the utilization of ubiquitous computing principles. We present results from the evaluation of the system prototype, for which a qualitative methodology was adopted. More concretely, we combined interviews and role-playing workshops with nurses and student nurses in order to (1) evaluate usability- and acceptability-related aspects and (2) evaluate the feasibility of the system to be used in real practice. The results indicate that the prototype design would further reinforce an already existing practice, allowing nurses to reallocate the patient responsibility more easily. Further, the system could support and improve the communication among nurses and reduce the number of unwanted interruptions. The paper concludes by describing how applying a user-centered approach in designing pervasive computing system is vital in order to make the technology seamlessly blend in with its context of use.

Impact of perceived quality and other influencing factors on emotional video experience

How quality, quality perception and emotions are related, and what this may imply for research on Q, is a question that to date still lacks an unambiguous answer. The study of this relationship is challenging and requires validated emotional stimuli as well as suitable methods and tools to evaluate their emotional impact. This paper shares findings from an inter-laboratory study (N=39), in which electroencephalography data and self-report data on experienced affect, content likeability and perceived quality were collected to evaluate the emotional impact of stimuli from a publicly available database aimed at evoking certain emotional responses. The results call for caution when evaluating emotional impact of such stimuli, as both the self-reported and EEG data point to a number of influencing factors that interfere with the emotion elicitation and need to be taken into account in future research.

Exploring diverse measures for evaluating QoE in the context of WebRTC

Enabling high Quality of Experience (QoE) with video-conferencing solutions based on Web Real-Time Communication (WebRTC) protocols anywhere, anytime, is challenging and triggers the exploration of new ways to gain QoE insights. In this paper, we share initial observations from a within-subjects experiment (N = 22) in which 2-party WebRTC-based audiovisual conversations took place under varying technical conditions. We collected self-report data, peripheral physiological data and application-level performance statistics with the overall aim of exploring their usefulness and compatibility for assessing QoE in the context of WebRTC. Our preliminary findings indicate that the varying quality is well-reflected in the self-reported overall quality and annoyance. However, this might not apply when considering the emotional valence ratings and ECG data, implying that other factors may play a role here.

Influence of high ambient illuminance and display luminance on readability and subjective preference

Many devices, such as tablets, smartphones, notebooks, fixed and portable navigation systems are used on a (nearly) daily basis, both in in- and outdoor environments. It is often argued that contextual factors, such as the ambient illuminance in relation to characteristics of the display (e.g., surface treatment, screen reflectance, display luminance …) may have a strong influence on the use of such devices and corresponding user experiences. However, the current understanding of these influence factors is still rather limited. In this work, we therefore focus in particular on the impact of lighting and display luminance on readability, visual performance, subjective experience and preference. A controlled lab study (N=18) with a within-subjects design was performed to evaluate two car displays (one glossy and one matte display) in conditions that simulate bright outdoor lighting conditions. Four ambient luminance levels and three display luminance settings were combined into 7 experimental conditions. More concretely, we investigated for each display: (1) whether and how readability and visual performance varied with the different combinations of ambient luminance and display luminance and (2) whether and how they influenced the subjective experience (through self-reported valence, annoyance, visual fatigue) and preference. The results indicate a limited, yet negative influence of increased ambient luminance and reduced contrast on visual performance and readability for both displays. Similarly, we found that the self-reported valence decreases and annoyance and visual fatigue increase as the contrast ratio decreases and ambient luminance increases. Overall, the impact is clearer for the matte display than for the glossy display.