Physical inactivity remains a critical global health issue, yet scalable strategies for sustained motivation are scarce. Conversational agents designed as simulated exercising peers (SEPs) represent a promising alternative, but their long-term impact is unclear. We report a six-month randomized controlled trial (N=280) comparing individuals exercising alone, with a human peer, or with a large language model-driven SEP. Results revealed a partnership paradox: human peers evoked stronger social presence, while AI peers provided steadier encouragement and more reliable working alliances. Humans motivated through authentic comparison and accountability, whereas AI peers fostered consistent, low-stakes support. These complementary strengths suggest that AI agents should not mimic human authenticity but augment it with reliability. Our findings advance human-agent interaction research and point to hybrid designs where human presence and AI consistency jointly sustain physical activity.

Cyberbullying has significant psychological implications, including increased levels of depression, anxiety, and stress. Despite these implications, there is a lack of real-time, accessible mechanisms that support victims, particularly young adults. This study developed and evaluated the effectiveness of a progressive web application that connects victims with certified professionals, e.g., guidance counselors, to seek psychological support. The app offers informational resources, such as videos and testimonials on prevention, intervention, and support, to educate and increase awareness among victims. The study was carried out over a 3-month longitudinal period from April 14 to July 14, 2024, with 286 young adults, most of whom were victims aged 18-34 from two higher education institutions (HEIs) in Nigeria, using a mixed-methods approach. The participants were randomly assigned to two groups: (a) experimental group (the group that used the app), (b) control group (the group that did not use the app). Our findings demonstrate the app's effectiveness in reducing depression, anxiety, and stress, increasing awareness, and a slight improvement in perceived support among participants in the experimental group. We discuss policy implications for integrating this application into educational frameworks and curricula development.

Disclosure-based cyberbullying is defined as sharing personal information without consent, often with malicious intentions. This affects young adults and leads to long-term personal damage (i.e., career, reputation, and family). Current strategies on social media platforms fall short of addressing this problem. We engaged 20 young adults (18-34) through a participatory design approach in co-designing solutions that reflect their concerns, needs, and desires. Participants were divided into three groups based on their cyberbullying experience as victim, discloser, or attacker. Our participants designed 15 solutions for prevention, intervention, support, and awareness. These solutions reveal the need for privacy control, anonymity, and autonomy for victims, a restorative justice system, social media accountability, and the involvement of influencers and content creators in awareness and education. We provide implications for progressive and adaptive social media awareness campaigns, a compassionate justice system, and soft control of personal information ownership.

Recently, various digital solutions have emerged to enhance the process of self-reflection, which can be crucial for personal growth and resilience. However, whether technology can meaningfully match or augment a traditional approach like pen or paper remains to be ascertained. Our objective was to build an better understanding of design paradigms’ role in introspection. Through formative iterations, informed by Self-Determination Theory (SDT), we designed and developed different tool formulations (Analogue, Digital, and Hybrid) for comparison. Participants (N = 48) received one variant, completing a pre- and post-six-week assessment with the Self Reflection and Insight Scale (SRIS) and intermediary self-reports for qualitative feedback. We found scores for Hybrid and Digital conditions change significantly, suggesting format decisions have meaningful impacts on the efficacy of designs to alter intrinsic motivation toward introspective behaviour. We also identify determinants and design considerations to help others conceive solutions to support or stimulate a component of broader well-being.

Rising unemployment has led to many discouraged job seekers. While the impact of job seekers’ motivation on interview performance is acknowledged in previous research, little attention has been given to understanding the effect of training on interview motivation and performance. We present InterviewApp, an online interview training tool aiming to support interview motivation through autonomy, relatedness and competence needs derived from Self-Determination Theory and, in turn, performance. Through a four-month study (N=135), we assess its effectiveness in supporting job seekers’ interview motivation and performance. Our results demonstrate the role of autonomy in mediating the effect of training on performance. We found that the intervention significantly affected the job seekers’ perceived autonomy. Furthermore, engagement with the recording and feedback features of the tool positively impacted performance. Overall, job seekers found InterviewApp helpful for online interview training and valued the provided expert feedback. These findings have implications for the design of online interview training tools and for behaviour change interventions to support employment.

Second-hand electronic devices are increasingly being sold online. Although more affordable and more environment-friendly than new products, second-hand devices, in particular those with storage capabilities, create security and privacy threats (e.g., malware or confidential data still stored on the device, aka remnant data). Previous work studied this issue from a technical point of view or only from the perspective of the sellers of the devices, but the perspective of the buyers has been largely overlooked. In this paper, we fill this gap and take a multi-disciplinary approach, focusing on the case of Switzerland. First, we conduct a brief legal analysis of the rights and obligations related to second-hand storage devices. Second, in order to understand the buyers' practices related to these devices and their beliefs about their legal rights and obligations, we deploy a survey in collaboration with a major online platform for transactions of second-hand goods. We demonstrate that the risks highlighted in prior research might not materialize, as many buyers do not inspect the content of the bought devices (e.g., they format it directly). We also found that none of the buyers uses forensic techniques. We identified that the buyers' decisions about remnant data depend on the type of data. For instance, for data with illegal content, they would keep the data to report it to the authorities, whereas for sensitive personal data they would either delete the data or contact the sellers. We identified several discrepancies between the actual legal rights/obligations and users' beliefs.

Internet users possess accounts on dozens of online services where they are often identified by one of their e-mail addresses. They often use the same address on multiple services and for communicating with their contacts. In this paper, we investigate attacks that enable an adversary (e.g., company, friend) to determine (stealthily or not) whether an individual, identified by their e-mail address, has an account on certain services (i.e., an account enumeration attack ). Such attacks on account privacy have serious implications as information about one’s accounts can be used to (1) profile them and (2) improve the effectiveness of phishing. We take a multifaceted approach and study these attacks through a combination of experiments (63 services), surveys (318 respondents), and focus groups (13 participants). We demonstrate the high vulnerability of popular services (93.7%) and the concerns of users about their account privacy, as well as their increased susceptibility to phishing e-mails that impersonate services on which they have an account. We also provide findings on the challenges in implementing countermeasures for service providers and on users’ ideas for enhancing their account privacy. Finally, our interaction with national data protection authorities led to the inclusion of recommendations in their developers’ guide.

Hybrid learning modalities, where learners can attend a course in-person or remotely, have gained particular significance in post-pandemic educational settings. In introductory programming courses, novices’ learning behaviour in the collaborative context of classrooms differs in hybrid mode from that of a traditional setting. Reflections from conducting an introductory programming course in hybrid mode led us to recognise the need for re-designing programming tools to support students’ collaborative learning practices. We conducted a participatory design study with nine students, directly engaging them in design to understand their interaction needs in hybrid pedagogical setups to enable effective collaboration during learning. Our findings first highlighted the difficulties that learners face in hybrid modes. The results then revealed learners’ preferences for design functionalities to enable collective notions, communication, autonomy, and regulation. Based on our findings, we discuss design principles and implications to inform the future design of collaborative programming environments for hybrid modes.

In recent years, various initiatives from within and outside the HCI field have encouraged researchers to improve research ethics, openness, and transparency in their empirical research. We quantify how the CHI literature might have changed in these three aspects by analyzing samples of 118 CHI 2017 and 127 CHI 2022 papers—randomly drawn and stratified across conference sessions. We operationalized research ethics, openness, and transparency into 45 criteria and manually annotated the sampled papers. The results show that the CHI 2022 sample was better in 18 criteria, but in the rest of the criteria, it has no improvement. The most noticeable improvements were related to research transparency (10 out of 17 criteria). We also explored the possibility of assisting the verification process by developing a proof-of-concept screening system. We tested this tool with eight criteria. Six of them achieved high accuracy and F1 score. We discuss the implications for future research practices and education.

Self-regulation of learning in programming has been extensively investigated, emphasising an individual's metacognitive and motivational regulation components. However, learning often happens in socially situated contexts, and little emphasis has been paid to studying social modes of regulation in programming. We designed Thyone, a collaborative Jupyter Notebook extension to support learners' programming regulation in an online classroom context with the overall aim to foster their intrinsic motivation toward programming. Thyone's salient features - Flowchart, Discuss and Share Cell - incorporate affordances for learners to co-regulate their learning and drive their motivation. In an exploratory quasi-experimental study, we investigated learners' engagement with Thyone's features and assessed its influence on their learning motivation in an introductory programming course. We found that Thyone facilitated the co-regulation of programming learning and that the users' engagement with Thyone appeared to positively influence components of their motivation: interest, autonomy, and relatedness. Our results inform the design of technological interventions to support co-regulation in programming learning.

Sharing multimedia content, without obtaining consent from the people involved causes multiparty privacy conflicts (MPCs). However, social-media platforms do not proactively protect users from the occurrence of MPCs. Hence, users resort to out-of-band, informal communication channels, attempting to mitigate such conflicts. So far, previous works have focused on hard interventions that do not adequately consider the contextual factors (e.g., social norms, cognitive priming) or are employed too late (i.e., the content has already been seen). In this work, we investigate the potential of conversational agents as a medium for negotiating and mitigating MPCs. We designed MediationBot, a mediator chatbot that encourages consent collection, enables users to explain their points of view, and proposes solutions to finding a middle ground. We evaluated our design using a Wizard-of-Oz experiment with N = 32 participants, where we found that MediationBot can effectively help participants to reach an agreement and to prevent MPCs. It produced a structured conversation where participants had well-clarified speaking turns. Overall, our participants found MediationBot to be supportive as it proposes useful middle-ground solutions. Our work informs the future design of mediator agents to support social-media users against MPCs.

Disclosing personal information significantly increases the likelihood of incidents of cyberbullying. This highlights the significance of investigating the relationships between various stakeholders in cyberbullying incidents. Our objective is to gain insight into the roles of the stakeholders, types, and typical paths of personal information in cyberbullying incidents. To achieve this, we conducted a large-scale survey with a representative sample of internet users from the United States and Nigeria (N = 1555). Our findings indicate that cyberbullying is often fueled by personal information that becomes known, directly or through social media, to other stakeholders. Cyberbullying incidents involve more than just attackers and victims; they can involve other stakeholders as third-parties 'disclosers' Both strangers and friends typically engage in such activities. Cyberbullying incidents are twice as common in Nigeria as in the United States. Our findings have implications for design, social-media literacy programs, and policy.

Direct-to-consumer genetic testing services are gaining momentum: As of today, companies such as 23andMe or AncestryDNA have already attracted 26 million customers. These services raise privacy concerns, exacerbated by the fact that their customers can then share their genomic data on platforms such as GEDmatch. Notwithstanding their right to learn about their genetic background or to share their genomic data, it is paramount that individuals realize that such a behavior damages their relatives' privacy (i.e., kin genomic privacy). In this paper, we present KGP Meter, a new online tool that provides means for raising awareness in the general public about the privacy risks of genomic data sharing. Our tool features various properties that makes it highly interactive, privacy-preserving (i.e., not requiring access to the actual genomic data), and user-friendly. It explores possible configurations in an optimized way and combines well-established graphical models with an entropy-based metric to compute kin genomic privacy scores. Our experiments show that KGP Meter is very responsive. We design and implement an interface that enables users to draw their family trees and indicate which of their relatives' genomes are known, and that communicates the resulting privacy scores to the users. We then analyze the usage of the tool and survey users to better understand users' perceptions towards these risks and evaluate our tool. We observe that most of them find the privacy score worrisome, and that the large majority of them find KGP Meter useful.

This article contributes results of a longitudinal field study of SkillsIdentifier, an employment tool originally designed and assessed in the United States (U.S.), to support “underrepresented” job seekers in identifying and articulating their employment skills. To understand whether the tool could support the needs of job seekers outside the U.S., we assessed it among 16 job seekers with limited education and language resources in Switzerland. While many of our results mirrored those of the U.S., we found that the tool was especially beneficial for non-French speaking immigrants who needed support describing their skills outside of their native language. We also found that listing skills like “active listening” without important context was insufficient and risked hiding key skills and meaning behind those skills to employers. Taking these factors into account, we illustrate the design implications of our findings and directions for practitioners who wish to design employment tools in support of job seekers, especially those who have traditionally been excluded from the labor market. We then provide insight into the potential for unintended consequences as a result of focusing solely on skills in a post-COVID labor market and contribute ways to mitigate them.

Although sharing multimedia content on online social networks (OSNs) has many benefits, publishing photos or videos of other people—without obtaining permission—can cause multiparty privacy conflicts (MPCs). Early studies developed technical solutions and dissuasive approaches to address MPCs. However, none of these studies involved, in the design process, the OSN users who have experienced MPCs. Hence, they possibly overlooked the valuable experiences these individuals have accrued. To fill this gap, we recruited participants specifically from this population of users, and we involved them in participatory design sessions to find solutions to reduce the incidence of MPCs. To frame the activities of our participants, we borrowed terminology and concepts from a well-known framework used in the justice systems. Over the course of several design sessions, our participants designed 10 solutions to mitigate MPCs. The designed solutions are based on different mechanisms, including preventing MPCs from occurring, dissuading users from sharing, resolving the conflicts, and educating users about community standards. We discuss the open design and research opportunities suggested by the designed solutions and contribute an ideal workflow that synthesizes the best of each solution. We contribute to the innovation of privacy-enhancing technologies to limit the incidence of MPCs in OSNs.

The use of fitness apps (some based on behavior change theories) is increasing. Recently a taxonomy mapped app features to the Basic Psychological Needs (BPNs) posited by the Self-Determination Theory (SDT), providing the opportunity to inform the design of fitness apps by this theory of human motivation. However, it is unknown if the user’s perceptions of such SDT-based design would support the BPNs. This is important as the SDT states that interventions supporting the BPNs produce long-term benefits. Following the taxonomy of app features based on SDT, we designed and developed Agon, an iPhone app. We deployed the app through a one-month field study involving 49 participants. The study allowed participants to use the app in their everyday lives, providing sufficient exposure for us to capture meaningful perceptions. This work contributes empirical evidence that the features included in our design correctly mapped to the Basic Psychological Needs. We discuss implications for researchers and designers targeting effective interventions.

Life-changing events (or LCEs) can alter a person's status quo and threaten well-being. Previous research investigated distinct LCEs, where participants already used technology routinely. This paper reports the results of two field studies through which we compared supports people refer to when experiencing different LCEs. Together with users of technology, our sampling included participants who specifically did not refer to online services and tools to seek help during their LCE. We found that popular services people refer to are inattentive to the needs of people experiencing an LCE as they do not allow forms of progressive engagement and disclosure within the service. We also found that popular services are imprudent as their design might expose users experiencing an LCE to more sources of stress. Finally, we found that these services are inapt to support these users as they do not provide direct forms of interactions with experts.

Abstract Technology integration in the workplace context has led to substantial growth in high- versus low-skilled jobs, and thus, further disparities between workers and those who were already unemployed. Technology use is also being used more frequently in the job search process, which could further lead to disparities, especially for job seekers experiencing marginalization. Thus, we conducted a controlled longitudinal field deployment of two employment-based tools—RevueCV and InterviewApp—among 46 Switzerland-based unemployed job seekers. Using the theory of planned behavior (TPB), we sought to understand how the tools affected job search self-efficacy, subjective norms and job search attitudes—the three factors that influence a job seekers’ job search intention. Although participants appreciated the support the two tools provided, and the inherent study benefits, our interview and survey results showed no substantial changes in their TPB values, primarily because the tools provided overlapping services with the local job placement offices. However, results of our interviews found autonomy, or the lack thereof, to be a key factor contributing to job seeker dissatisfaction. We introduce the concept of self-regulation to the TPB as an explanatory construct and contribute design and theoretical implications to support autonomy among job seekers with less control of their job search.

Individuals share increasing amounts of personal multimedia data, exposing themselves (uploaders) as well as others (data subjects). Non-consensual sharing of multimedia data that depicts others raises so-called multiparty privacy conflicts (MPCs), which can have severe consequences. To limit the incidence of MPCs, a family of Precautionary mechanisms have recently been developed that force uploaders to collaborate with the other data subjects to prevent MPCs. However, there is still very little work on understanding how users perceive the precautionary mechanisms together with which ones they prefer and why. In addition, precautionary mechanisms have some limitations, e.g., they require linking content to the co-owners' identity. Therefore, we also explore alternatives to precautionary mechanisms and propose a new class of solutions-Dissuasive mechanisms-that aim at deterring the uploaders from sharing without consent. We then present a user-centric comparison of precautionary and dissuasive mechanisms, through a large-scale survey (N = 1792; a representative sample of adult Internet users). Our results showed that respondents prefer precautionary to dissuasive mechanisms. These enforce collaboration, provide more control to the data subjects, but also they reduce uploaders' uncertainty around what is considered appropriate for sharing. We learned that threatening legal consequences is the most desirable dissuasive mechanism, and that respondents prefer the mechanisms that threaten users with immediate consequences (compared with delayed consequences). Dissuasive mechanisms are in fact well received by frequent sharers and older users, while precautionary mechanisms are preferred by women and younger users. We discuss the implications for design, including considerations about side leakages, consent collection, and censorship.

Web developers can (and do) include subresources such as scripts, stylesheets and images in their webpages. Such subresources might be stored on content delivery networks (CDNs). This practice creates security and privacy risks, should a subresource be corrupted. The subresource integrity (SRI) recommendation, released in mid-2016 by the W3C, enables developers to include digests in their webpages in order for web browsers to verify the integrity of subresources before loading them. In this paper, we conduct the first large-scale longitudinal study of the use of SRI on the Web by analyzing massive crawls (≈ 3B URLs) of the Web over the last 3.5 years. Our results show that the adoption of SRI is modest (≈), but grows at an increasing rate and is highly influenced by the practices of popular library developers (e.g., Bootstrap) and CDN operators (e.g., jsDelivr). We complement our analysis about SRI with a survey of web developers (N=): It shows that a substantial proportion of developers know SRI and understand its basic functioning, but most of them ignore important aspects of the recommendation. The results of the survey also show that the integration of SRI by developers is mostly manual – hence not scalable and error prone. This calls for a better integration of SRI in build tools.

Nowadays, thousands of popular applications are designed to help users improve their lives through behavioural adjustment (e.g., meditate more, stay hydrated). However, our understanding of how certain design features align with constructs of behavior theories remain limited. We analyze 208 apps from the Apple App Store and identified 12 design features afforded by current tools that we classified according to the Self-Determination Theory. The taxonomy reported in this paper, we argue, provides a simple tool for designers to evaluate how specific features, and combination of features, may work to motivate users towards their desired goals. Additionally, the presented taxonomy is intended to help researchers test new interventions by discussing relevant research gaps.

App stores provide access to millions of different programs that users can download on their computers. Developers can also make their programs available for download on their websites and host the program files either directly on their website or on third-party platforms, such as mirrors. In the latter case, as users download the software without any vetting from the developers, they should take the necessary precautions to ensure that it is authentic. One way to accomplish this is to check that the published file’s integrity verification code—the checksum—matches that (if provided) of the downloaded file. To date, however, there is little evidence to suggest that such a process is effective. Even worse, very few usability studies about it exist. In this article, we provide the first comprehensive study that assesses the usability and effectiveness of the manual checksum verification process. First, by means of an in-situ experiment with 40 participants and eye-tracking technology, we show that the process is cumbersome and error-prone. Second, after a 4-month-long in-the-wild experiment with 134 participants, we demonstrate how our proposed solution—a Chrome extension that verifies checksums automatically—significantly reduces human errors, improves coverage, and has only limited impact on usability. It also confirms that, sadly, only a tiny minority of websites that link to executable files in our sample provide checksums (0.01%), which is a strong call to action for web standards bodies, service providers, and content creators to increase the use of file integrity verification on their properties.

People do not exercise as much and as regularly as they should. To support users in adopting healthy exercise routines, app designers integrate persuasive techniques in their apps. In this study, we focus on two of these techniques, i.e., offering tangible rewards and sending motivational messages to users. Past research has demonstrated the effects of these techniques in nudging recipients to increase their physical activity levels. However, the effect of these interventions on the intrinsic motivation of the participants has not yet been studied. We conducted a 10-month study involving 208 participants; this research consisted of a 3-month baseline (pre-phase), a 4-month experiment and a 3-month follow-up (post-phase). The participants were randomly assigned to one of the following three interventions: either they receive money ((i.) through a fixed incentive or (ii.) a lottery), or (iii.) informative messages. Their daily goal was to walk 10K steps. Through their smart phones, we recorded how many steps they walked every day. These interventions had no effect on the main outcome variable (i.e., the number of steps). However, the manipulations produced a detrimental effect on the intrinsic motivation of the participants, measured through a standardized questionnaire. This negative effect extended into the follow-up period. Our study reveals that tangible rewards and motivational messages decrease the intrinsic motivation of the participants, hence their connected physical activity. In our findings, we highlight the importance of intrinsic motivation in setting up healthy exercise routines that will be carried on autonomously by the participants after the period of the intervention. Finally, we present implications for the design of persuasive apps.

Internet users can download software for their computers from app stores (e.g., Mac App Store and Windows Store) or from other sources, such as the developers' websites. Most Internet users in the US rely on the latter, according to our representative study, which makes them directly responsible for the content they download. To enable users to detect if the downloaded files have been corrupted, developers can publish a checksum together with the link to the program file; users can then manually verify that the checksum matches the one they obtain from the downloaded file. In this paper, we assess the prevalence of such behavior among the general Internet population in the US (N=2,000), and we develop easy-to-use tools for users and developers to automate both the process of checksum verification and generation. Specifically, we propose an extension to the recent W3C specification for sub-resource integrity in order to provide integrity protection for download links. Also, we develop an extension for the popular Chrome browser that computes and verifies checksums of downloaded files automatically, and an extension for the WordPress CMS that developers can use to easily attach checksums to their remote content. Our in situ experiments with 40participants demonstrate the usability and effectiveness issues of checksums verification, and shows user desirability for our extension.

We present findings of a study with 62 subjects who had 796 of their outgoing mobile phone calls recorded and transcribed for their later annotation—by highlighting important information shared during calls. We found that patterns in these calls (numbers, names, interrogative adverbs), as well as some contextual parameters, are better indicators of annotation needs than the callers' profile or call quality. Callers highlight information in both parties' turns (caller and callee) more often than highlighting solely information provided by the callee, which is mostly due to annotating questions with contextual information for the highlights in the callee's turns. We discuss how this behavior changes according to call purpose. Finally, we found that annotation needs change over time: whereas some annotations might not be considered relevant after weeks, others originally considered irrelevant might become important archival notes. We present implications of these findings for the design of mobile phone annotation tools.

The goal of this work is to provide a fundamental understanding of the daily information needs of people through a large-scale, in-depth, quantitative investigation. To this end, we have conducted one of the most comprehensive studies of information needs to date, spanning a 3-month period and involving more than 100 users. The study employed a contextual experience sampling method, a snippet-based diary technique using SMS technology, and an online Web diary to gather in situ insights into the types of needs that occur from day to day, how those needs are addressed, and how contextual, technological, and demographic factors impact on those needs. Our results not only complement earlier studies but also provide a new understanding of the intricacies of people’s daily information needs.

Most online service providers offer free services to users and in part, these services collect and monetize personally identifiable information (PII), primarily via targeted advertisements. Against this backdrop of economic exploitation of PII, it is vital to understand the value that users put to their own PII. Although studies have tried to discover how users value their privacy, little is known about how users value their PII while browsing, or the exploitation of their PII. Extracting valuations of PII from users is non-trivial - surveys cannot be relied on as they do not gather information of the context where PII is being released, thus reducing validity of answers. In this work, we rely on refined Experience Sampling - a data collection method that probes users to valuate their PII at the time and place where it was generated in order to minimize retrospective recall and hence increase measurement validity. For obtaining an honest valuation of PII, we use a reverse second price auction. We developed a web browser plugin and had 168 users - living in Spain - install and use this plugin for 2 weeks in order to extract valuations of PII in different contexts.

We propose a conceptual model that explains the relationship between the users' personality profile and their satisfaction with basic mobile phone services (calls, messages, and simple GPRS/3G services). The model captures direct and indirect effects on satisfaction by means of two variables: actual mobile phone usage and perceived usability of the related services. We empirically validate the model with data gathered from 603 customers of a telecommunication operator, and find that: (1) extroversion , conscientiousness , and intellect have a significant impact on customer satisfaction—positively for the first two traits and negatively for the latter; (2) extroversion positively influences mobile phone usage; and (3) extroversion and conscientiousness positively influence the users' perceived usability of mobile services. Interestingly, usability has the strongest positive impact on satisfaction, whereas mobile phone usage has a negative impact on satisfaction. We discuss key findings of this model and propose several implications for the design of mobile phone services.

Note-taking has been largely studied in contexts of work meetings. However, often people need to remember information exchanged in informal situations, such as during mobile phone conversations. In this paper we present a study conducted with 59 subjects who had their phone calls semi-automatically transcribed for later annotation. Analysis of the 621 calls and the subjects' annotation behavior revealed that phone recall is indeed a relevant user need. Furthermore, identifying patterns in phone calls such as numbers and names provide better indicators of annotation than variables related to the callers' profile, context of calls, or quality of service. Our findings suggest implications for the design of mobile phone annotation tools.

This paper presents ethnographic observations, a diary study and a large-scale quantitative questionnaire (n=395) designed to study the reasons for adoption and refusal of context-aware mobile applications. Through a qualitative study we identify 24 user needs that these applications fulfill and 9 barriers for adoption. We found that for many of the identified needs the end-goal is not that of receiving information, thus complementing work on mobile information needs. Also, this work offers an actionable list of obstacles that prevent contextual services to reach a larger audience. Finally, our findings suggest the opportunity to develop novel mobile applications that fulfill needs in the activity and personal contextual dimensions, and that of developing an application store for feature phones.

People share pictures online to increase their social presence. However, recent studies have shown that most of the content shared in social networks is not looked at by peers. Proper metadata can be generated and used to improve the retrieval of this content. In spite of this, we still lack solutions for collecting valid descriptors of content that can be used effectively in the context of social information navigation. In this paper, we propose a mechanism based on persuasive techniques to support peers in providing metadata for multimedia content that can be used for a person's self-promotion. Through an iterative design and experimentation process, we demonstrate how this methodology can be used effectively to increase one's social presence thus building more enjoyable, rich, and creative content that is shared in the social network. In addition, we highlight implications that inform the design of social games with a purpose.

Medication compliance is a critical component in the success of any medical treatment. However, only 50% of patients correctly adhere to their prescription regimens. Mobile and ubiquitous technologies have been proposed to tackle this challenge, mainly in the form of memory aid solutions that remind patients to take their pills. However, most of these methods do not engage patients in shifting their behavior towards better compliance. In this paper, we propose and evaluate a mobile phone-based game called MoviPill that persuades patients to be more adherent to their medication prescription by means of social competition. In a 6-week user study conducted with 18 elders, the use of MoviPill improved both their compliance to take the daily medication and also the accuracy of the drug intake time according to the prescribed time. Moreover, the improvement in the latter increased from 43% to 56% when we considered only participants that had any interest in games, which reveals the importance of applying persuasive techniques in a personalized manner. We conclude with a set of implications for the design of persuasive mobile solutions in this domain.

The mobile Internet offers anytime, anywhere access to a wealth of information to billions of users across the globe. However, the mobile Internet represents a challenging information access platform due to the inherent limitations of mobile environments, limitations that go beyond simple screen size and network issues. Mobile users often have information needs which are impacted by contexts such as location and time. Furthermore, human beings are social creatures that often seek out new strategies for sharing knowledge and information in mobile settings. To investigate the social aspect of mobile search, we have developed SocialSearchBrowser (SSB), a novel proof-of-concept interface that incorporates social networking capabilities with key mobile contexts to improve the search and information discovery experience of mobile users. In this paper, we present the results of an exploratory field study of SSB and outline key implications for the design of next generation mobile information access services.

As the mobile Internet continues to grow, there is an increasing need to provide users with effective search and information access services. In order to build more effective mobile search services, we must first understand the impact that various interface choices have on mobile users. For example, the majority of mobile location-based search services are built on top of a map visualization, but is this intuitive design-decision the optimal interface choice from a human centric perspective? In order to tackle this fundamental design question, we have developed two proactive mobile search interfaces (one map-based and the other text-based) that utilize key mobile contexts to improve the search and information discovery experience of mobile users. In this paper, we present the results of an exploratory field study of these two interfaces - involving 34 users over a 1 month period - where we focus in particular on the impact that the type of user interface (e.g. map vs text) has on the search and information discovery experience of mobile users. We highlight the main usage results - including that maps are not the interface of choice for certain information access tasks - and outline key implications for the design of next generation mobile search services.

Popular content in video sharing websites (e.g., YouTube) is usually replicated via identical copies or near-duplicates. These duplicates are usually studied because they pose a threat to site owners in terms of wasted disk space, or privacy infringements. Furthermore, this content might potentially hinder the users' experience in these websites. The research presented in this article focuses around the central argument that there is no agreement on the technical definition of what these near-duplicates are, and, more importantly, there is no strong evidence that users of video sharing websites would like this content to be removed. Most scholars define near-duplicate video clips (NDVC) by means of non-semantic features (e.g., different image/audio quality), while a few also include semantic features (i.e., different videos of similar content). However, it is unclear what features contribute to the human perception of near-duplicate videos. The findings of four large scale online surveys that were carried out in the context of our research confirm the relevance of both types of features. Some of our findings confirm the adopted definitions of NDVC whereas other findings are surprising: Near-duplicate videos with different image quality, audio quality, or with/without overlays were perceived as NDVC. However, the same could not be verified when videos differed by more than one of these features at the same time. With respect to semantics, it is yet unclear the exact role that it plays in relation to the features that make videos alike. From a user's perspective, participants preferred in most cases to see only one of the NDVC in the search results of a video search query and they were more tolerant to changes in the audio than in the video tracks. Based on all these findings, we propose a new user-centric NDVC definition and present implications for how duplicate content should be dealt with by video sharing Web sites.

Speech and typed text are two common input modalities for mobile phones. However, little research has compared them in their ability to support annotation and retrieval of digital pictures on mobile devices. In this paper, we report the results of a month-long field study in which participants took pictures with their camera phones and had the choice of adding annotations using speech, typed text, or both. Subsequently, the same subjects participated in a controlled experiment where they were asked to retrieve images based on annotations as well as retrieve annotations based on images in order to study the ability of each modality to effectively support users' recall of the previously captured pictures. Results demonstrate that each modality has advantages and shortcomings for the production of tags and retrieval of pictures. Several guidelines are suggested when designing tagging applications for portable devices.

Popular content in video sharing web sites (e.g., YouTube) is usually duplicated. Most scholars define near-duplicate video clips (NDVC) based on non-semantic features (e.g., different image/audio quality), while a few also include semantic features (different videos of similar content). However, it is unclear what features contribute to the human perception of similar videos. Findings of two large scale online surveys (N = 1003) confirm the relevance of both types of features. While some of our findings confirm the adopted definitions of NDVC, other findings are surprising. For example, videos that vary in visual content - by overlaying or inserting additional information - may not be perceived as near-duplicate versions of the original videos. Conversely, two different videos with distinct sounds, people, and scenarios were considered to be NDVC because they shared the same semantics (none of the pairs had additional information). Furthermore, the exact role played by semantics in relation to the features that make videos alike is still an open question. In most cases, participants preferred to see only one of the NDVC in the search results of a video search query and they were more tolerant to changes in the audio than in the video tracks. Finally, we propose a user-centric NDVC definition and present implications for how duplicate content should be dealt with by video sharing websites.

This paper presents an algorithm that detects misunderstandings in collaborative work at a distance. It analyses the movements of collaborators' eyes on the shared workspace, their utterances containing references about this workspace, and the availability of 'remote' deictic gestures. This method is based on two findings: 1. participants look at the points they are talking about in their message; 2. their gazes are more dense around these points compared to other random looks in the same timeframe. The algorithm associates the distance between the gazes of the emitter and gazes of the receiver of a message with the probability that the recipient did not understand the message.

Software developers are rooted in the written form of their code, yet they often draw diagrams representing their code. Unfortunately, we still know little about how and why they create these diagrams, and so there is little research to inform the design of visual tools to support developers' work. This paper presents findings from semi-structured interviews that have been validated with a structured survey. Results show that most of the diagrams had a transient nature because of the high cost of changing whiteboard sketches to electronic renderings. Diagrams that documented design decisions were often externalized in these temporary drawings and then subsequently lost. Current visualization tools and the software development practices that we observed do not solve these issues, but these results suggest several directions for future research.

Explicit Referencing is a mechanism for enabling deictic gestures in on-line communication. Little is known about the impact of ER on distance problem solving. In this paper, we report on a study where 120 students (60 pairs) had to solve a problem collaboratively, at a distance, using chat tools that differed in the way a user may relate an utterance to the task context. Results indicate that team performance is improved by explicit referencing mechanisms. However, when Explicit Referencing is implemented in a way that is detrimental to the linearity of the conversation, resulting in the visual dispersion or scattering of messages, its use has negative consequences for collaborative work at a distance. The role of a linear message history in the collaboration mechanisms was equally important than that of Explicit Referencing.

This paper presents the creation, deployment, and evaluation of a large-scale, spatially-stable, paper-based visualization of a software system. The visualization was created for a single team, who were involved systematically in its initial design and subsequent design iterations. The evaluation indicates that the visualization supported the "onboarding" scenario but otherwise failed to realize the research team's expectations. We present several lessons learned, and cautions to future research into large-scale, spatially-stable visualizations of software systems.