Aggression is a socially complex behaviour that intelligent virtual agents (IVAs) must convincingly convey in applications such as customer service and conflict training. Despite its importance, aggression remains understudied: prior work has focused on basic emotions and unimodal cues, providing little insight into how aggression can be modelled multimodally or systematically scaled by intensity. We present a psychologically grounded model that parametrises language, voice, body movement and facial expressions, across four aggression levels. We evaluated the model in two studies with 38 flight attendants. Experiment 1 tested unimodal cues, showing all modalities except language conveyed aggression gradients. Experiment 2 extended this by combining modalities, demonstrating that coordinated multimodal integration stabilised weaker language cues and produced perceptually robust aggression levels (low, mid, and high) with body and facial cues carrying most weight. Our work contributes the first validated multimodal, multi-level aggression model for IVAs, offering design principles for broader socially expressive agents.

Responsiveness in large language model (LLM) applications is widely assumed to be critical, yet the impact of latency on user behavior and perception of output quality has not been systematically explored. We report a controlled experiment varying time-to-first-token latency (2, 9, 20 seconds) across two taxonomy-driven knowledge task types (Creation and Advice). Log analyses reveal that user interaction behaviors were robust to latency, yet varied by task type: Creation tasks elicited more frequent prompting than Advice tasks. In contrast, participants who experienced 2-second latencies rated the LLM’s outputs less thoughtful and useful than those who experienced 9- or 20-second latencies. Participants attributed delays to AI deliberation, though long waits occasionally shifted this interpretation toward frustration or concerns about reliability. Overall, this work demonstrates that latency is not simply a cost to reduce but a tunable design variable with ethical implications. We offer design strategies for enhancing human-LLM interaction.

System-imposed wait times can significantly disrupt digital workflows, affecting user experience and task performance. Prior HCI research has examined how temporal feedback, such as feedback mode (Elapsed-Time vs. Remaining-Time) shapes wait-time perception. However, few studies have investigated how such feedback influences users’ downstream task performance, as well as overall affective and cognitive experience. To study these effects, we conducted an online experiment where 425 participants performing a visual reasoning task experienced a 10-, 30-, or 60-second wait with a Remaining-Time, Elapsed-Time, or No Time Display. Findings show that temporal feedback mode shapes how waiting is perceived: Remaining-Time feedback increased frustration relative to Elapsed-Time feedback, while No Time Display made waits feel longer and heightened ambiguity. Notably, these experiential differences did not translate into differences in post-wait task performance. Integrating psychophysical and cognitive science perspectives, we discuss implications for implementing temporal feedback in latency-prone digital systems.

LLM-assisted writing has seen rapid adoption in interpersonal communication, yet current systems often fail to capture the subtle tones essential for effectiveness. Email writing exemplifies this challenge: effective messages require careful alignment with intent, relationship, and context beyond mere fluency. Through formative studies, we identified three key challenges: articulating nuanced communicative intent, making modifications at multiple levels of granularity, and reusing effective tone strategies across messages. We developed PersonaMail, a system that addresses these gaps through structured communication factor exploration, granular editing controls, and adaptive reuse of successful strategies. Our evaluation compared PersonaMail against standard LLM interfaces, and showed improved efficiency in both immediate and repeated use, alongside higher user satisfaction. We contribute design implications for AI-assisted communication systems that prioritize interpersonal nuance over generic text generation.

Given the widespread presence of screens during meals, the notion that digital engagement is inherently incompatible with mindfulness. We demonstrate how the strategic design of digital content can enhance two core aspects of mindful eating: slow eating and food awareness. Our research unfolded in three sequential studies: (1). Zoom Eating Study: Contrary to the assumption that video-watching leads to distraction and overeating, this study revealed that subtle video speed manipulations—can promote slower eating (by 15.31%) and controlled food intake (by 9.65%) while maintaining meal satiation and satisfaction. (2). Co-design workshop: Informed the development of ViFeed, a video playback system strategically incorporating subtle speed adjustments and glanceable visual cues. (3). Field Study: A week-long deployment of ViFeed in daily eating demonstrated its efficacy in fostering food awareness, food appreciation, and sustained engagement. By bridging the gap between ideal mindfulness practices and screen-based behaviors, this work offers insights for designing digital-wellbeing interventions that align with, rather than against, existing habits. © 2025 Copyright held by the owner/author(s).

Advancements in Virtual Reality (VR) technology have opened new frontiers in medical education, igniting interest among medical educators to incorporate it into mainstream curriculum, complementing traditional training modalities such as manikin training. Despite numerous VR simulators on the market, their uptake in medical education remains limited. This paper explores the acceptability and educational effectiveness of VR in the context of vaginal childbirth delivery training, with the simulator providing a walkthrough for the second and third stages of labour, contrasting it with established manikin-based methods. We conducted a large-scale empirical study with 117 medical students, revealing a significant 24.9% improvement in knowledge scores when using VR as compared to manikin. However, VR received significantly lower self-reported feasibility scores in Confidence, Usability, Enjoyment, Feedback and Presence, indicating low acceptance. The study provides critical insights into the relationship between technological innovation and educational impact, guiding future integration of VR into medical training curricula.

The rise of multitasking in contemporary lifestyles has positioned audio-first content as an essential medium for information consumption. We present AudioXtend, an approach to augment audiobook experiences during daily tasks by integrating glanceable, AI-generated visuals through optical see-through head-mounted displays (OHMDs). Our initial study showed that these visual augmentations not only preserved users’ primary task efficiency but also dramatically enhanced immediate auditory content recall by 33.3% and 7-day recall by 32.7%, alongside a marked improvement in narrative engagement. Through participatory design workshops involving digital arts designers, we crafted a set of design principles for visual augmentations that are attuned to the requirements of multitaskers. Finally, a 3-day take-home field study further revealed new insights for everyday use, underscoring the potential of assisted reality (aR) to enhance heads-up listening and incidental learning experiences.

Mindfulness technologies have gained research interest in recent years. We explore the use of smart-glasses (Optical Head Mounted Displays or OHMDs) for breath-based mindfulness practice as a well-being technology for everyday users. Since OHMDs do not occlude the wearer’s view, practitioners can access the digital environment while performing daily activities. Through our pilot series, we identified suitable visual and auditory attributes for OHMD mindfulness sessions in casual walking settings, and combined user-preferred features into our proposed Mindful Moments design. Results on physiological, sustained attention and self-reported mindfulness measures suggest that Mindful Moments facilitates higher state mindfulness than the Control. Its results proved comparable to the state-of-the-art Walking Meditation, while also being more accessible, convenient, and easy for novice practitioners to implement in everyday environments. We further evaluate Mindful Moments in a realistic setting, enhancing current understanding of mindfulness practice on OHMDs, thereby contributing a technique for improved health and well-being.

The emergent Optical Head-Mounted Display (OHMD) platform has made mobile reading possible by superimposing digital text onto users’ view of the environment. However, mobile reading through OHMD needs to be effectively balanced with the user’s environmental awareness. Hence, a series of studies were conducted to explore how text spacing strategies facilitate such balance. Through these studies, it was found that increasing spacing within the text can significantly enhance mobile reading on OHMDs in both simple and complex navigation scenarios and that such benefits mainly come from increasing the inter-line spacing, but not inter-word spacing. Compared with existing positioning strategies, increasing inter-line spacing improves mobile OHMD information reading in terms of reading speed (11.9% faster), walking speed (3.7% faster), and switching between reading and navigation (106.8% more accurate and 33% faster).

Improving volunteer performance leads to better caregiving in dementia care settings. However, caregiving knowledge systems have been focused on eliciting and sharing expert, primary caregiver knowledge, rather than volunteer-provided knowledge. Through the use of an experience prototype, we explored the content of volunteer caregiver knowledge and identified ways in which such non-expert knowledge can be useful to dementia care. By using lay language, sharing information specific to the client and collaboratively finding strategies for interaction, volunteers were able to boost the effectiveness of future volunteers. Therapists who reviewed the content affirmed the reliability of volunteer caregiver knowledge and placed value on its recency, variety and its ability to help bridge language and professional barriers. We discuss how future systems designed for eliciting and sharing volunteer caregiver knowledge can be used to promote better dementia care.