a b s t r a c tA wealth of studies in the field of user experience have tried to conceptualize new measures of product quality and inquire into how the overall goodness of a product is formed on the basis of product quality perceptions. An interesting question relates to how the perception as well as the relative dominance of different product qualities evolve across different phases in the adoption of a product. However, temporality of experience poses substantial challenges to traditional reductive evaluation approaches. In this paper we present an alternative methodological approach for studying how users' experiences with interactive products develop over time. The approach lies in the elicitation of rich qualitative insights in the form of experience narratives, combined with content-analytical approaches for the aggregation of idiosyncratic insights into generalized knowledge. We describe a tool designed for eliciting rich experience narratives retrospectively, and illustrate this tool by means of a study that inquired into how users' experiences with mobile phones change over the first 6 months of use. We use the insights of the study to validate and extend a framework of temporality proposed by Karapanos et al. (2009b).

Scatterplots and parallel coordinate plots (PCPs) that can both be used to assess correlation visually. In this paper, we compare these two visualization methods in a controlled user experiment. More specifically, 25 participants were asked to report observed correlation as a function of the sample correlation under varying conditions of visualization method, sample size and observation time. A statistical model is proposed to describe the correlation judgment process. The accuracy and the bias in the judgments in different conditions are established by interpreting the parameters in this model. A discriminability index is proposed to characterize the performance accuracy in each experimental condition. Moreover, a statistical test is applied to derive whether or not the human sensation scale differs from a theoretically optimal (that is, unbiased) judgment scale. Based on these analyses, we conclude that users can reliably distinguish twice as many different correlation levels when using scatterplots as when using PCPs. We also find that there is a bias towards reporting negative correlations when using PCPs. Therefore, we conclude that scatterplots are more effective than parallel plots in supporting visual correlation analysis.

Even in the current computer age, there are still many important application areas, such as early architectural design, where traditional tools like sketching on paper continue to be preferred by many professionals over computer-based tools. There is a growing awareness that there are often very good grounds for this preference. Hence, instead of trying to replace such traditional ways of working, it is now often considered more opportune to try and preserve the strengths of these traditional ways of working, while at the same time improving them by providing access to new media. This is one of the main objectives of the augmented reality approach that we adopt here. In this paper, we specifically discuss the realization of a tool for early architectural design on an existing augmented reality system, called the Visual Interaction Platform. We describe the development process, the resulting tool and its performance for elementary tasks such as positioning and overdrawing. We also identify directions for future research and applications. q

The way we experience and evaluate interactive products develops over time. An exploratory study aimed at understanding how users form evaluative judgments during the first experiences with a product as well as after four weeks of use. Goodness, an evaluative judgment related to the overall satisfaction with the product, was largely formed on the basis of pragmatic aspects (i.e. utility and usability) during the first experiences; after four weeks of use identification (i.e. what the products expresses about its owner) became a dominant aspect of how good a product is. Surprisingly, beauty judgments were largely affected by stimulation (e.g. novelty) during the first experiences. Over time stimulation lost its power to make the product beautiful in the users' eyes.

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