Redirected walking (RDW) is a technique that allows users to navigate larger physical spaces in virtual reality (VR) environments by manipulating the users’ view of the virtual world. In this study, we investigate the effect of adding spatial audio elements to curvature gains in RDW aiming to increase the perceptual threshold for the manipulation and allowing for higher levels of unnoticed redirection. We conducted a user study (n = 18), evaluating perceptual thresholds across conditions with and without spatial audio elements across different curvature gains. We found that spatial audio can significantly increase thresholds with a large effect size. This finding indicates the value of spatial audio for RDW. It could facilitate higher levels of redirection, while maintaining a convincing experience, leading to more freedom to navigate virtual environments in even smaller physical spaces.

When a task is repeated, it becomes part of procedural memory.This type of memory dedicated to movement is called 'muscle memory', which allows one to perform actions unconsciously.Within the context of social media, muscle memory builds up if one uses SM applications frequently.In this paper, we investigate the effects of muscle memory within Instagram, and report the following findings: We designed a user study examining the speed and accuracy of using a newly changed interface which showed slower reaction time and more errors.Combining these results with users' perceived feelings lead us to conclude that in specific UX interface changes muscle memory can be applied as a dark pattern.

Negative body perception can negatively affect one’s health, as it can lead to depression and eating disorders. Body appreciation on the other hand, is about accepting, respecting, loving, and appreciating the body, and has been associated with self-esteem, optimism, life satisfaction, and other factors related to the well-being. The aim of this research project is to investigate whether lower body appreciation can be identified by visualising the discrepancy between someone’s actual self and their ideal self (i.e., the distance between these two domains of the self). This discrepancy is visualised through an avatar creation task using The Sims 4 in which participants have to create an avatar of (1) the way they actually look, and (2) their ideal image. Participants’ body appreciation was measured using the BAS-2 body appreciation scale, which contains ten statements about one’s feelings towards their body. Actual/ideal self-discrepancy was calculated by measuring the number of changes that were made in order to get from the actual body to the ideal body. Analysis of the results reveals that (a) adjustments to certain avatar traits significantly correlate with body appreciation scores, and (b) some gender differences are notably predictive, e.g., with respect to “muscle”, “middle body”, and ”weight” changes. As such, we may conclude that the developed avatar creation task which measures the discrepancy between the actual and ideal self, can indeed be used as a tool to identify (lower) body appreciation.

Waiting for a system to respond always will be a factor in human–computer interaction. This is deployed by spinners, progress bars, skeleton-screens and other means. This project studies experiencing longer waits along the lines of ‘no activity’ (progress bar), ‘passive waiting’ (reading) and ‘active waiting’ (doing something). For the latter, a novel method is introduced: users actively swipe an image after which it disappears and the content underneath will unveil, as if it were a scratch card. A between-subjects experiment (n = 410) was conducted using a mobile website in 3 conditions to gauge the effects on estimated waiting time and enjoyment. The ‘no activity’ and ‘active waiting’ conditions were estimated faster than the ‘passive waiting’ condition. The ‘passive’ and ‘active’ waiting conditions were significantly more enjoyable than the ‘no activity’ condition. When combining waiting time estimation (shorter is preferable) and enjoyment (higher is preferable) the ‘active waiting’ condition yielded better results.

Ephemeral media platforms allow users to send content in a format that automatically deletes the content after the recipient has accessed it – a phenomenon known as the ‘burn after reading’ principle. This study investigates whether awareness of the burn after read principle results in improved recognition memory for pictures. An experiment is designed where participants interact with pictures using a social media application. In Version A, participants are made aware of the persistent nature of the pictures, in Version B, participants are made aware of the ephemeral nature. Thereafter, participants are presented with the pictures again and must identify whether or not they previously encountered the exact same picture. Results showed that the burn after read principle does have a significant impact on accuracy in recognising pictures and the time spent watching them. Awareness of the burn after read principle resulted in better recognition memory for pictures and longer viewing times in the ephemeral application. This finding is in accordance with existing findings on the relationship between ephemerality and recognition memory.

This paper presents the results of a user study carried out to evaluate an application prototype in which an audio-visual chat conversation between two users is augmented by pictures related to the topics of that conversation. The prototype analyses the conversation and deducts the topic of conversation by means of a keyword tree, augmented by an ontology. Then it retrieves pictures from Flickr based on this topic, after which the pictures are shown to the users. This mechanism is called conversation-based image retrieval. 15 participants were recruited for this user study; the duration of one session was approximately 30 minutes. Eye tracking and questionnaires were used to evaluate participants' experiences. We found that participants value the use of pictures to augment an audio-visual chat application. Furthermore, participants claimed they would use it in a social context: talking to family, friends and acquaintances. One significant improvement over the prototype would be to use their own pictures (personal user-generated content) instead of just random pictures.

This paper investigates the influence of interface styles on problem solving performance. It is often assumed that performance on problem solving tasks improves when users are assisted by externalizing task-related information on the interface. Although externalization requires less recall and relieves working memory, it does not instigate planning, understanding and knowledge acquisition. Without this assistance, task-information must be internalized, stored in the user's memory, leading to more planning and thinking and perhaps to better performance and knowledge. Another variable that can influence behavior is "Need for Cognition" (NFC), the tendency to engage in effortful cognitive tasks. We investigated the effects of interface style and cognitive style on performance using a conference planning application. Interface style influenced behavior and performance, but NFC did not. The internalization interface led to more planful behavior and smarter solutions. When planning and learning are the aim, designers should thus beware of giving a user (too) much assistance. Understanding how people react to interface information can be crucial in designing effective software, especially important in the areas of education and learning.

This research investigates how externalizing information in program-interfaces influences problem solving performance. Externalization as screen-representation provides relevant interface-feedback, and remembering certain task-related knowledge becomes unnecessary, relieving working memory (WM). Examples are visual feedback aids such as "graying out" non-applicable menu-items. Differently, when certain task-related information is unavailable, it needs to be internalized, stored in WM. We examined the hypotheses that externalization yields better performance during initial learning, while later, internalization yields better performance and knowledge. Two versions (internalized & externalized) of an isomorph of the "missionaries and cannibals" problem were tested. 30 subjects solved 6 problems, then performed a distraction task erasing WM, and solved 3 more problems. Also knowledge of the problem's rules and states was tested. Internalization yielded better knowledge and reaching less dead-end problem-states. Time needed, steps and error-rates were in the expected direction, but not significantly. This research contributes to GUI design-guidelines for human-computer interaction of problem-solving tasks.

This study investigates the influence of structure and reading-manipulation, and more importantly, the interaction between these two variables on usability of hypertexts. Four types of hypertexts are distinguished, differing in structure (hierarchical, or hierarchical with partial linearity) and reading-manipulation (scrolling or paging). A fifth extra hypertext containing a hierarchical structure with partial linearity and both paging and scrolling was also investigated. The information itself, a city guide about Utrecht with cultural and tourist information, was exactly the same in all hypertexts. Three aspects of usability were examined: efficiency, ease of learning and user-satisfaction. These aspects are measured by performance on 24 search tasks and a task reflecting insight into the structure of the hypertext. Also, questions about the structure of the hypertext and satisfaction with the system had to be answered. The results indicated that structure and reading-manipulation did not interact. There were, however, significant main effects of structure and reading-manipulation. A purely hierarchical structure was frequently more usable than a hierarchical structure with partial linearity, and scrolling appeared to be more useful than paging. The fifth alternative hypertext seemed slightly more usable than the hypertexts with linearity, but less usable than purely hierarchical hypertexts. The findings combined suggest that a purely hierarchical hypertext with scrolling is most useful, probably because this structure and kind of reading-manipulation both provide a clear insight into the structure of the hypertext. We assume this insight to be necessary for adequate performance.