Two problems may arise when an intelligent (recommender) system elicits users' preferences. First, there may be a mismatch between the quantitative preference representations in most preference models and the users' mental preference models. Giving exact numbers, e.g., such as "I like 30 days of vacation 2.5 times better than 28 days" is difficult for people. Second, the elicitation process can greatly influence the acquired model (e.g., people may prefer different options based on whether a choice is represented as a loss or gain). We explored these issues in three studies. In the first experiment we presented users with different preference elicitation methods and found that cognitively less demanding methods were perceived low in effort and high in liking. However, for methods enabling users to be more expressive, the perceived effort was not an indicator of how much the methods were liked. We thus hypothesized that users are willing to spend more effort if the feedback mechanism enables them to be more expressive. We examined this hypothesis in two follow-up studies. In the second experiment, we explored the trade-off between giving detailed preference feedback and effort. We found that familiarity with and opinion about an item are important factors mediating this trade-off. Additionally, affective feedback was preferred over a finer grained one-dimensional rating scale for giving additional detail. In the third study, we explored the influence of the interface on the elicitation process in a participatory set-up. People considered it helpful to be able to explore the link between their interests, preferences and the desirability of outcomes. We also confirmed that people do not want to spend additional effort in cases where it seemed unnecessary. Based on the findings, we propose four design guidelines to foster interface design of preference elicitation from a user view.

Explicitly considering human values in the design process of socio-technical systems has become a responsibility of designers. It is, however, challenging to design for values because (1) relevant values must be identified and communicated between all stakeholders and designers and (2) stakeholders' values differ and trade-offs must be made. We focus on the first aspect, which requires elicitation of stakeholders' situated values, i.e. values relevant to a specific real life context. Available techniques to elicit knowledge and requirements from stakeholders lack in providing the context and means for reflection needed to elicit situated values as well as an explicit concept of value. In this paper we present our design of a tool to support active elicitation of stakeholders' values and communication between stakeholders and designers. We conducted an exploratory user study in which we compared the suitability of methods used in social sciences for (1) eliciting situated values, (2) supporting people's expressions of values and (3) being implemented in value elicitation tool. Based on the outcomes we propose a design for a value elicitation tool that consists of a mobile application used by stakeholders for data collection and in-situ self-reflection, and a website used collaboratively by designers and stakeholders to analyse and communicate values. Discussion focuses on contributions to value sensitive design.

Motivation -To investigate how facilitation, material and group composition influence creativity in and outcomes of participatory design sessions.Research approach -Several participatory design workshops were held with end-users and designers. Different materials were used to trigger creativity. Analysis of effects of group facilitation, material and composition was based on observational notes, prototypes and interview data. Findings/Design -(1) Specific allocation of time for breaks and questions are useful. Examples or prototypes tied into the explanation of the domain and design challenge support the participants' understanding. (2) Paper prototypes are useful for non-designers to trigger creativity and allow for interaction between the group members while creating new prototypes. (3) Groups should be composed to contain a domain expert, designer and end-users as well as someone taking the role of a moderator leading the group work.Research limitations/Implications -We did not follow a strictly conditional experiment set-up with our sessions. For an in-depth and systematic analysis of influencing factors a rigid set-up is advised.Originality/Value -The research makes a contribution to an investigation of factors influencing the process and outcome of participatory design sessions.Take away message -To allow for creativity and collaboration, participatory design sessions need to be set-up with care. Summarizing, groups should be composed of endusers, designers, domain experts and have a designated moderator. Prototypes are useful in the briefing, and should be provided to each group as paper versions to be used in the creative process. The researcher has the crucial task of facilitating the session, allowing enough time for questions and breaks and adapt explanations to the knowledge of the participants.

The impact of ubiquitous technology and social media on our lives is rapidly increasing. We explicitly need to consider personal values affected or violated by these systems. Value-sensitive design can guide a designer in building systems that account for human values. However, the framework lacks clear steps to guide elicitation of stakeholders' values. We argue that developing tools for value elicitation that designers can use or give to stakeholders is a feasible solution to this challenge. Crucial in eliciting values is that a stakeholder has to have an understanding about her own values and how they relate in importance. This requires self-reflection. Self-reflection, in turn, requires thinking or analysing one's behaviour in meaningful moments over a long period of time. In this paper, we investigate how current methods from various disciplines can be combined and applied in a tool supporting reflection on personal values. We present an exploratory study investigating photo elicitation and a value questionnaire as methods for expressing and eliciting values with a tool. Based on the results we present an envisioned mobile personal informatics application that triggers people to reflect about their values in real-life contexts.

We investigate people's attitudes toward the possible use of negotiation support systems (NSS) in different social contexts and the consequences for their design. To explore functional requirements and social acceptance in different use contexts, we followed a threestep approach. In the first step, we conducted a number of focus groups with negotiation experts. Second, we conducted focus groups with potential users. The focus groups were a qualitative exploration of people's ideas about NSS that led to design guidelines for mobile NSS. Third, we conducted an online survey (a) to find out in which situations people consider a mobile NSS socially acceptable, (b) to find the factors and relationships that influence this acceptance in the different situations and social contexts, and (c) to investigate the consequences of people's attitudes toward NSS for the system's design. The data showed that subjective norm is an important factor influencing the intention to use the system and that the acceptance of NSS depends on the use context. Therefore, we argue that NSS should be designed not only merely as tools being used in the actual negotiation but also as social devices harnessing social networks to provide support in all negotiation phases.