User experience (UX) summarizes user perceptions and responses resulting from the interaction with a product, system, or service. The User Experience Questionnaire (UEQ) is one standardized instrument for measuring UX. With six scales, it identifies areas in which product improvements will have the highest impact. In this paper, we evaluate the reliability and validity of this questionnaire. The data of N = 1, 121 participants who interacted with one of 23 products indicated an acceptable to good reliability of all scales. The results show, however, that the scales were not independent of each other. Combining perspicuity, efficiency, and dependability to pragmatic aspects as well as novelty and stimulation to hedonic aspects of UX improved the model fit significantly. The systematic variations of product properties and correlations with the System Usability Scale (SUS) in a second experiment with N=499 participants supported the validity of these two factors. Practical implications of the results are discussed.

Modern mobile phones are equipped with many sensors, which can increasingly be used to sense various environmental phenomena. In particular, mobile sensing has enabled crowdsourced data collection at an unprecedented scale. However, as laypersons are involved in this, concerns regarding the data quality arise. This work explores the gamification of smartphone-based measurement processes in practice by embedding a sensing task into a mobile minigame. The underlying idea is – rather than to educate the user on how to correctly perform a measurement task – to opportunistically execute the measurement in the background once the smartphone is in a suitable context. To this end, this paper presents the design and evaluation of SpaceMaze, a smartphone game with the goal of minimising user error by introducing appropriate game mechanics to influence the phone context, using the example of mobile noise level monitoring. A large user study that compares SpaceMaze to two non-gamified apps for noise level monitoring (N = 360 in total) shows that SpaceMaze can successfully reduce user errors when compared to simple non-gamified ambient noise level monitoring applications and that the minigame is generally perceived as being enjoyable. Solutions for remaining problems, such as noise generated by the players, are discussed.

Passive Haptic Learning (PHL) describes the learning of a motion, sequence or pattern without voluntary involvement of attention, focus or motivation through a haptic interface. In previous PHL studies about teaching Morse code, we suspect that active learning processes were at least partially involved in causing extraordinarily high learning rates. Therefore we conduct a similar, 50-participant user study to investigate whether PHL is able to teach Morse code without active attention. Our study design differs from previous studies by preventing active learning explicitly (no feedback given) and implicitly (non-Morse patterns, tests prevent learning by rule of elimination) for three groups. Two other groups get the same feedback as was present in other studies. Our results show much lower learning rates when there is no active learning possible. Including active learning, we replicate the same learning results as have been reported. This suggests that our suspicion was correct and that PHL of Morse Code is possible, but greatly limited. Further studies about PHL must pay attention to whether their study design allows participants to learn actively - even small amounts of information that is actively learned may have a great impact on learning performance.

Reading and understanding source code is a major task in software development. Code comprehension depends on the quality of code, which is impacted by code structure and identifier naming. In this paper we empirically investigated whether longer but more descriptive identifier names improve code comprehension compared to short names, as they represent useful information in more detail. In a web-based study 88 Java developers were asked to locate a semantic defect in source code snippets. With descriptive identifier names, developers spent more time in the lines of code before the actual defect occurred and changed their reading direction less often, finding the semantic defect about 14% faster than with shorter but less descriptive identifier names. These effects disappeared when developers searched for a syntax error, i.e., when no in-depth understanding of the code was required. Interestingly, the style of identifier names had a clear impact on program comprehension for more experienced developers but not for less experienced developers.

Wearables like smartwatches or fitness trackers are increasingly entering everyday life. This offers new and unexplored opportunities to use their unique features - like the ability to act as vibrotactile actuators - as interfaces in computer games to increase game immersion. Current tactile cues in games are mostly restricted to event based-feedback and practically exclusive to console gaming. This paper presents LifeTact, a system which informs players about remaining hit points through a tactile heartbeat. The Tactile heartbeat is emitted via existing wearables like smartwatches or fitness trackers. The system was implemented and evaluated in a between-subject study with gamers, who rated the system as innovative, beneficial to the user experience and immersive.