publications

2025

1. 

   The Role of Drone’s Digital Facial Emotions and Gaze in Shaping Individuals’ Social Proxemics and Interpretation

   Robin Bretin, Mohamed Khamis, Emily Cross, and 1 more author

   J. Hum.-Robot Interact., Feb 2025

   Just Accepted

   Abs DOI

   The potential for drones to engage with people and find applications in social contexts is often constrained by their mechanical design, leading to concerns and negative associations that significantly affect people’s acceptance of drones in their personal space. In this study, we explore how social cues can impact the spatial dynamic of Human–Drone Interaction (HDI). Within a fully immersive virtual environment, 25 participants engaged with and navigated around a drone that communicated several facial emotions on a digital display such as Joy, Sadness and Anger, and enacted distinct ”gaze” behaviors (i.e., following participants or averting its gaze). Our results indicate that participants responded to the drone’s gaze in a manner akin to what is reported during human interaction: maintaining a greater distance when the drone established eye contact and instinctively getting closer when it averted its gaze. A more granular analysis revealed that participants who lacked prior familiarity with drones or possessed neutral to positive attitudes toward them demonstrated a higher sensitivity to the drone’s digital facial emotions. This finding highlights the potential for leveraging social cues to facilitate the integration of drones into various human-centric environments and tailor their design and behavior to suit specific individuals and situations.

2024

1. 

   Co-existing with Drones: A Virtual Exploration of Proxemic Behaviours and Users’ Insights on Social Drones

   Robin Bretin, Emily Cross, and Mohamed Khamis

   International Journal of Social Robotics, Mar 2024

   Abs DOI

   Numerous studies have investigated proxemics in the context of human–robot interactions, but little is known about whether these insights can be applied to human–drone interactions (HDI). As drones become more common in social settings, it is crucial to ensure they navigate in a socially acceptable and human-friendly way. Understanding how individuals position themselves around drones is vital to promote user well-being and drones’ social acceptance. However, real-world constraints and risks associated with drones flying in close proximity to participants have limited research in this field. Virtual reality is a promising alternative for investigating HDI, as prior research suggests. This paper presents a proxemic user study (N = 45) in virtual reality, examining how drone height and framing influence participants’ proxemic preferences. The study also explores participants’ perceptions of social drones and their vision for the future of flying robots. Our findings show that drone height significantly impacts participants’ preferred interpersonal distance, while framing had no significant effect. Thoughts on how participants envision social drones (e.g., interaction, design, applications) reveal interpersonal differences but also shows overall consistency over time. While the study demonstrates the value of using virtual reality for HDI experiments, further research is necessary to determine the generalizability of our findings to real-world HDI scenarios.

2. 

   "Pikachu would electrocute people who are misbehaving": Expert, Guardian and Child Perspectives on Automated Embodied Moderators for Safeguarding Children in Social Virtual Reality

   Cristina Fiani, Robin Bretin , Shaun Alexander Macdonald, and 2 more authors

   In Proceedings of the 2024 CHI Conference on Human Factors in Computing Systems, May 2024

   Abs DOI

   Automated embodied moderation has the potential to create safer spaces for children in social VR, providing a protective figure that takes action to mitigate harmful interactions. However, little is known about how such moderation should be employed in practice. Through interviews with 16 experts in online child safety and psychology, and workshops with 8 guardians and 13 children, we contribute a comprehensive overview of how Automated Embodied Moderators (AEMs) can safeguard children in social VR. We explore perceived concerns, benefits and preferences across the stakeholder groups and gather first-of-their-kind recommendations and reflections around AEM design. The results stress the need to adapt AEMs to children, whether victims or harassers, based on age and development, emphasising empowerment, psychological impact and humans/guardians-in-the-loop. Our work provokes new participatory design-led directions to consider in the development of AEMs for children in social VR taking child, guardian, and expert insights into account.

3. 

   Understanding Dynamic Human-Robot Proxemics in the Case of Four-Legged Canine-Inspired Robots

   Xiangmin Xu, Emma Liying Li, Mohamed Khamis, and 2 more authors

   Sep 2024

   arXiv:2302.10729

   Abs arXiv

   Recently, quadruped robots have been well developed with potential applications in different areas, such as care homes, hospitals, and other social areas. To ensure their integration in such social contexts, it is essential to understand people’s proxemic preferences around such robots. In this paper, we designed a human-quadruped-robot interaction study (N = 32) to investigate the effect of 1) different facing orientations and 2) the gaze of a moving robot on human proxemic distance. Our work covers both static and dynamic interaction scenarios. We found a statistically significant effect of both the robot’s facing direction and its gaze on preferred personal distances. The distances humans established towards certain robot behavioral modes reflect their attitudes, thereby guiding the design of future autonomous robots.

4. 

   Evaluating Transferable Emotion Expressions for Zoomorphic Social Robots using VR Prototyping‘

   Shaun Macdonald, Robin Bretin, and Salma ElSayed

   In 2024 IEEE International Symposium on Mixed and Augmented Reality (ISMAR), Oct 2024

   ISSN: 2473-0726

   Abs DOI

   Zoomorphic robots have the potential to offer companionship and well-being as accessible, low-maintenance alternatives to pet ownership. Many such robots, however, feature limited emotional expression, restricting their potential for rich affective relationships with everyday domestic users. Additionally, exploring this design space using hardware prototyping is obstructed by physical and logistical constraints. We leveraged virtual reality rapid prototyping with passive haptic interaction to conduct a broad mixed-methods evaluation of emotion expression modalities and participatory prototyping of multimodal expressions. We found differences in recognisability, effectiveness and user empathy between modalities while highlighting the importance of facial expressions and the benefits of combining animal-like and unambiguous modalities. We use our findings to inform promising directions for the affective zoomorphic robot design and potential implementations via hardware modification or augmented reality, then discuss how VR prototyping makes this field more accessible to designers and researchers.

2023

1. 

   “Do I Run Away?”: Proximity, Stress and Discomfort in Human-Drone Interaction in Real and Virtual Environments

   Robin Bretin, Mohamed Khamis, and Emily Cross

   In Human-Computer Interaction – INTERACT 2023, Oct 2023

   Awarded Abs DOI

   IFIP TC13 Pioneers’ Award for Best Doctoral Student Paper, Reviewers’ Choice Best Paper Award

   Social drones are autonomous flying machines designed to operate in inhabited environments. Yet, little is known about how their proximity might impact people’s well-being. This knowledge is critical as drones are often perceived as potential threats due to their design (e.g., visible propellers, unpleasant noise) and capabilities (e.g., moving at high speed, surveillance). In parallel, Virtual Reality (VR) is a promising tool to study human–drone interactions. However, important questions remain as to whether VR is ecologically valid for exploring human–drone interactions. Here, we present a between-within subjects user study (N = 42) showing that participants’ stress significantly differs between different drone states and locations. They felt more comfortable when the drone retreated from their personal space. Discomfort and stress were strongly correlated with the perceived drone’s threat level. Similar findings were found across real and virtual environments. We demonstrate that drones’ behaviour and proximity can threaten peoples’ well-being and comfort, and propose evidence-based guidelines to mitigate these impacts.

2. 

   Big Buddy: Exploring Child Reactions and Parental Perceptions towards a Simulated Embodied Moderating System for Social Virtual Reality

   Cristina Fiani, Robin Bretin, Mark Mcgill, and 1 more author

   In Proceedings of the 22nd Annual ACM Interaction Design and Children Conference, Jun 2023

   Abs DOI

   Children experience new forms of harassment in Social Virtual Reality (VR), often inaccessible to parental oversight. We aimed to understand how an artificial intelligent moderator safeguarding children from harassment in social VR is perceived by children and parents, by introducing “Big Buddy”, a Wizard-of-Oz embodied AI-moderator. 43 children (aged 8-16) played a tower-block-construction game in a simulated Social VR classroom where fictitious competitors disrupted their game and, in experimental conditions where present, Big Buddy intervened. We measured children’s perceptions after the disruptions, towards Big Buddy, and the moderation actions it took. Children felt significantly less sad and safer when Big Buddy suspended the saboteur. Parents (n=17) noted Big Buddy’s usefulness and felt reassured but would remain in the supervision loop. We present the first empirical research of a VR-embodied AI-moderator with children’s and parents’ perspectives, and propose design directions for embodied AI-moderators in Social VR.

3. 

   Big Buddy: A Simulated Embodied Moderating System to Mitigate Children’s Reaction to Provocative Situations within Social Virtual Reality

   Cristina Fiani, Robin Bretin, Mark McGill, and 1 more author

   In Extended Abstracts of the 2023 CHI Conference on Human Factors in Computing Systems, Apr 2023

   Abs DOI

   The use of social Virtual Reality (VR) among children is increasing, but with it comes new forms of harassment that can be difficult for parents to monitor. To address this issue, we have developed "Big Buddy", a prototype AI-moderator that aims to safeguard children from potential harassment in social VR. We conducted a study in which 43 children (aged 8-16) participated in a simulated social VR classroom, with fictitious competitors disrupting their game. When Big Buddy intervened, the children reported feeling significantly less negative emotions and felt safer. This is the first study to empirically examine the use of an embodied AI-moderator in social VR from the perspective of children, and it provides important insights for designing AI-moderators in social VR.

2022

1. 

   Co-existing With a Drone: Using Virtual Reality to Investigate the Effect of the Drone’s Height and Cover Story on Proxemic Behaviours

   Robin Bretin , Emily S. Cross, and Mohamed Khamis

   In Extended Abstracts of the 2022 CHI Conference on Human Factors in Computing Systems, Apr 2022

   Abs DOI

   While a growing body of literature has begun to examine proxemics in light of human–robot interactions, it is unclear how insights gained from human–human or human–robot interaction (HRI) apply during human–drone interactions (HDI). Understanding why and how people locate themselves around drones is thus critical to ensure drones are socially acceptable. In this paper, we present a proxemic user study (N=45) in virtual reality focusing on 1) the impact of the drone’s height and 2) the type of cover story used to introduce the drone (framing) on participants’ proxemic preferences. We found that the flying height has a statistically significant effect on the preferred interpersonal distance, whereas no evidence was found related to how the drone was framed. While results also highlight the value of using Virtual Reality for HDI experiments, further research must be carried out to investigate how these findings translate from the virtual to the real world.

2. 

   The Feet in Human-Centred Security: Investigating Foot-Based User Authentication for Public Displays

   Kieran Watson, Robin Bretin, Mohamed Khamis, and 1 more author

   In Extended Abstracts of the 2022 CHI Conference on Human Factors in Computing Systems, Apr 2022

   Abs DOI

   A large body of work investigated touch, mid-air, and gaze-based user authentication. However, little is known about authentication using other human body parts. In this paper, we investigate the idea of foot-based user authentication for public displays (e.g., ticket machines). We conducted a user study (N=13) on a virtual prototype, FeetAuth, on which participants use their dominant foot to rotate through PIN elements (0–9) that are augmented along a circular layout using augmented reality (AR) technology. We investigate FeetAuth  in combination with three different layouts: Floor-based, Spatial, and Egocentric, finding that Floor-based FeetAuth resulted in the highest usability with 4-digit PIN entry as fast as M=6.71 (SD=0.67). Participants perceived foot-based authentication as socially acceptable and highlighted its accessibility. Our investigation of foot-based authentication paves the way for further studies on the use of the human body for user authentication.