Online financial scams represent a long-standing and serious threat for which people seek help. We present a study to understand people’s in situ motivations for engaging with scams and the help needs they express before, during, and after encountering a scam. We identify the main emotions scammers exploited (e.g., fear, hope) and characterize how they did so. We examine factors—such as financial insecurity and legal precarity—which elevate people’s risk of engaging with specific scams and experiencing harm. We indicate when people sought help and describe their help-seeking needs and emotions at different stages of the scam. We discuss how these needs could be met through the design of contextually-specific prevention, diagnostic, mitigation, and recovery interventions.

A growing body of qualitative research has identified contextual risk factors that elevate people’s chances of experiencing digital-safety attacks. However, the lack of quantitative data on the population-level distribution of these risk factors prevents policymakers and tech companies from developing targeted, evidence-based interventions to improve digital safety. To address this gap, we surveyed 5,001 adults in the United States to analyze: (1) the frequency of and relationship between digital-safety attacks (e.g., scams, harassment, account hacking), and (2) how these attacks align with 10 contextual risk factors. Nearly half of our respondents identify as resource constrained, which significantly correlates with higher likelihood of experiencing four common attacks. We also present qualitative insights to expand our understanding of the factors beyond the existing literature (e.g., “prominence” included high-visibility roles in local communities). This study provides the first large-scale quantitative analysis correlating digital-safety attacks with contextual risk factors and demographics.

Technology provides youth (ages 10--17) with near-constant opportunities for learning, communication, and self-expression. It can also expose them to technology-facilitated abuse: harassment, coercion, fraud, and more. The ability of youth to navigate such abuse is crucial for their well-being and development. A recent advisory by the U.S. Surgeon General called for better support of youth, including that youth should ''reach out for help.'' However, little is known about how youth seek help or otherwise cope with technology-facilitated abuse. Through a qualitative study in the U.S., we examine how youth engage in self-reliance, seek help from others, and how others seek help on a youth's behalf. We discuss these strategies and outline opportunities for how the HCI community can better support youth who experience technology-facilitated abuse.

Creating information technologies intended for broad use that allow everyone to participate safely online—which we refer to as inclusive digital safety —requires understanding and addressing the digital-safety needs of a diverse range of users who face elevated risk of technology-facilitated attacks or disproportionate harm from such attacks—i.e., at-risk users . This article draws from more than 9 years of our work at Google to understand and support the digital safety of at-risk users—including survivors of intimate partner abuse, people involved with political campaigns, content creators, youth, and more—in technology intended for broad use. Among our learnings is that designing for inclusive digital safety across widely varied user needs and dynamic contexts is a wicked problem with no “correct” solution. Given this, we describe frameworks and design principles we have developed to help make at-risk research findings practically applicable to technologies intended for broad use and lessons we have learned about communicating them to practitioners.

Research involving at-risk users—that is, users who are more likely to experience a digital attack or to be disproportionately affected when harm from such an attack occurs—can pose significant safety challenges to both users and researchers. Nevertheless, pursuing research in computer security & privacy (S&P) is crucial to understanding how to meet the digital-safety needs of at-risk users and to design safer technology for all. To standardize and bolster safer research involving such users, we offer an analysis of 196 academic works to elicit 14 research risks and 36 safety practices used by a growing community of researchers. We pair this inconsistent set of reported safety practices with oral histories from 12 domain experts to contribute scaffolded and consolidated pragmatic guidance that researchers can use to plan, execute, and share safer digital-safety research involving at-risk users. We conclude by suggesting areas for future research regarding the reporting, study, and funding of at-risk user research.

The seamless integration of technology into the lives of youth has raised concerns about their digital safety. While prior work has explored youth experiences with physical, sexual, and emotional threats—such as bullying and trafficking—a comprehensive and in-depth understanding of the myriad threats that youth experience is needed. By synthesizing the perspectives of 36 youth and 65 adult participants from the U.S., we provide an overview of today’s complex digital-safety landscape. We describe attacks youth experienced, how these moved across platforms and into the physical world, and the resulting harms. We also describe protective practices the youth and the adults who support them took to prevent, mitigate, and recover from attacks, and key barriers to doing this effectively. Our findings provide a broad perspective to help improve digital safety for youth and set directions for future work.

Assessing the trustworthiness of information online is complicated. Literacy-based paradigms are both widely used to help and widely critiqued. We conducted a study with 35 Gen Zers from across the U.S. to understand how they assess information online. We found that they tended to encounter—rather than search for—information, and that those encounters were shaped more by social motivations than by truth-seeking queries. For them, information processing is fundamentally a social practice. Gen Zers interpreted online information together, as aspirational members of social groups. Our participants sought information sensibility: a socially-informed awareness of the value of information encountered online. We outline key challenges they faced and practices they used to make sense of information. Our findings suggest that like their information sensibility practices, solutions and strategies to address misinformation should be embedded in social contexts online.

Online hate and harassment poses a threat to the digital safety of people globally. In light of this risk, there is a need to equip as many people as possible with advice to stay safer online. We interviewed 24 experts to understand what threats and advice internet users should prioritize to prevent or mitigate harm. As part of this, we asked experts to evaluate 45 pieces of existing hate-and-harassment-specific digital-safety advice to understand why they felt advice was viable or not. We find that experts frequently had competing perspectives for which threats and advice they would prioritize. We synthesize sources of disagreement, while also highlighting the primary threats and advice where experts concurred. Our results inform immediate efforts to protect users from online hate and harassment, as well as more expansive socio-technical efforts to establish enduring safety.

During the COVID-19 pandemic, risk negotiation became an important precursor to in-person contact. For young adults, social planning generally occurs through computer-mediated communication. Given the importance of social connectedness for mental health and academic engagement, we sought to understand how young adults plan in-person meetups over computer-mediated communication in the context of the pandemic. We present a qualitative study that explores young adults’ risk negotiation during the COVID-19 pandemic, a period of conflicting public health guidance. Inspired by cultural probe studies, we invited participants to express their preferred precautions for one week as they planned in-person meetups. We interviewed and surveyed participants about their experiences. Through qualitative analysis, we identify strategies for risk negotiation, social complexities that impede risk negotiation, and emotional consequences of risk negotiation. Our findings have implications for AI-mediated support for risk negotiation and assertive communication more generally. We explore tensions between risks and potential benefits of such systems.

Content creators—social media personalities with large audiences on platforms like Instagram, TikTok, and YouTube—face a heightened risk of online hate and harassment. We surveyed 135 creators to understand their personal experiences with attacks (including toxic comments, impersonation, stalking, and more), the coping practices they employ, and gaps they experience with existing solutions (such as moderation or reporting). We find that while a majority of creators view audience interactions favorably, nearly every creator could recall at least one incident of hate and harassment, and attacks are a regular occurrence for one in three creators. As a result of hate and harassment, creators report self-censoring their content and leaving platforms. Through their personal stories, their attitudes towards platform-provided tools, and their strategies for coping with attacks and harms, we inform the broader design space for how to better protect people online from hate and harassment.

At-risk users are people who experience risk factors that augment or amplify their chances of being digitally attacked and/or suffering disproportionate harms. In this systematization work, we present a framework for reasoning about at-risk users based on a wide-ranging meta-analysis of 95 papers. Across the varied populations that we examined (e.g., children, activists, people with disabilities), we identified 10 unifying contextual risk factors —such as marginalization and access to a sensitive resource —that augment or amplify digital-safety risks and their resulting harms. We also identified technical and non-technical practices that at-risk users adopt to attempt to protect themselves from digital-safety risks. We use this framework to discuss barriers that limit at-risk users’ ability or willingness to take protective actions. We believe that researchers and technology creators can use our framework to identify and shape research investments to benefit at-risk users, and to guide technology design to better support at-risk users.

We argue that existing security, privacy, and antiabuse protections fail to address the growing threat of online hate and harassment. In order for our community to understand and address this gap, we propose a taxonomy for reasoning about online hate and harassment. Our taxonomy draws on over 150 interdisciplinary research papers that cover disparate threats ranging from intimate partner violence to coordinated mobs. In the process, we identify seven classes of attacks—such as toxic content and surveillance—that each stem from different attacker capabilities and intents. We also provide longitudinal evidence from a three-year survey that hate and harassment is a pervasive, growing experience for online users, particularly for at-risk communities like young adults and people who identify as LGBTQ+. Responding to each class of hate and harassment requires a unique strategy and we highlight five such potential research directions that ultimately empower individuals, communities, and platforms to do so.

South Asia faces one of the largest gender gaps online globally, and online safety is one of the main barriers to gender-equitable Internet access [GSMA, 2015]. To better understand the gendered risks and coping practices online in South Asia, we present a qualitative study of the online abuse experiences and coping practices of 199 people who identified as women and 6 NGO staff from India, Pakistan, and Bangladesh, using a feminist analysis. We found that a majority of our participants regularly contended with online abuse, experiencing three major abuse types: cyberstalking, impersonation, and personal content leakages. Consequences of abuse included emotional harm, reputation damage, and physical and sexual violence. Participants coped through informal channels rather than through technological protections or law enforcement. Altogether, our findings point to opportunities for designs, policies, and algorithms to improve women's safety online in South Asia.

Addressing digital security and privacy issues can be particularly difficult for users who face challenging circumstances. We performed semi-structured interviews with residents and staff at 4 transitional homeless shelters in the U.S. San Francisco Bay Area (n=15 residents, 3 staff) to explore their digital security and privacy challenges. Based on these interviews, we outline four tough times themes --- challenges experienced by our financially insecure participants that impacted their digital security and privacy --- which included: (1) limited financial resources, (2) limited access to reliable devices and Internet, (3) untrusted relationships, and (4) ongoing stress. We provide examples of how each theme impacts digital security and privacy practices and needs. We then use these themes to provide a framework outlining opportunities for technology creators to better support users facing security and privacy challenges related to financial insecurity.

Web browser warnings should help protect people from malware, phishing, and network attacks. Adhering to warnings keeps people safer online. Recent improvements in warning design have raised adherence rates, but they could still be higher. And prior work suggests many people still do not understand them. Thus, two challenges remain: increasing both comprehension and adherence rates. To dig deeper into user decision making and comprehension of warnings, we performed an experience sampling study of web browser security warnings, which involved surveying over 6,000 Chrome and Firefox users in situ to gather reasons for adhering or not to real warnings. We find these reasons are many and vary with context. Contrary to older prior work, we do not find a single dominant failure in modern warning design---like habituation---that prevents effective decisions. We conclude that further improvements to warnings will require solving a range of smaller contextual misunderstandings.

We present a qualitative study of the digital privacy and security motivations, practices, and challenges of survivors of intimate partner abuse (IPA). This paper provides a framework for organizing survivors' technology practices and challenges into three phases: physical control, escape, and life apart. This three-phase framework combines technology practices with three phases of abuse to provide an empirically sound method for technology creators to consider how survivors of IPA can leverage new and existing technologies. Overall, our results suggest that the usability of and control over privacy and security functions should be or continue to be high priorities for technology creators seeking ways to better support survivors of IPA.

Many technologies assume a single user will use an account or device. But account and device sharing situations (when 2+ people use a single device or account) may arise during everyday life. We present results from a multiple-methods study of device and account sharing practices among household members and their relations. Among our findings are that device and account sharing was common, and mobile phones were often shared despite being considered "personal" devices. Based on our study results, we organize sharing practices into a taxonomy of six sharing types--distinct patterns of what, why, and how people shared. We also present two themes that cut across sharing types: that (1) trust in sharees and (2) convenience highly influenced sharing practices. Based on these findings, we discuss implications for study and technology design.

Browsers warn users when the privacy of an SSL/TLS connection might be at risk. An ideal SSL warning would empower users to make informed decisions and, failing that, guide confused users to safety. Unfortunately, users struggle to understand and often disregard real SSL warnings. We report on the task of designing a new SSL warning, with the goal of improving comprehension and adherence. We designed a new SSL warning based on recommendations from warning literature and tested our proposal with microsurveys and a field experiment. We ultimately failed at our goal of a well-understood warning. However, nearly 30% more total users chose to remain safe after seeing our warning. We attribute this success to opinionated design, which promotes safety with visual cues. Subsequently, our proposal was released as the new Google Chrome SSL warning. We raise questions about warning comprehension advice and recommend that other warning designers use opinionated design.

Vehicles increasingly include features that rely on hi-tech sensors and recording; however, little is known of public attitudes toward such recording. We use two studies, an online survey (n=349) and an interview-based study (n=15), to examine perceptions of vehicle-based sensing and recording. We focus on: 1) how vehicle-based recording and sensing may differ from perceptions of current recording; 2) factors that impact comfort with vehicle-based recording for hypothetical drivers versus bystanders; and 3) perceptions of potential privacy-preserving techniques. We find that vehicle-based recording challenges current mental models of recording awareness. Comfort tends to depend on perceived benefits, which can vary by stakeholder type. Perceived privacy in spaces near cars can also impact comfort and reflect mental models of private spaces as well as the range of potentially sensitive activities people perform in and near cars. Privacy-preserving techniques may increase perceived comfort but may require addressing trust and usability issues.

Website owners use web analytics tools to better understand their visitors for a range of purposes. However, there is limited understanding of how owners of non-transactional websites use and benefit from web analytics. Through semi-structured interviews (n=18) with non-transactional web analytics users we explore these uses and benefits. Participants tend to use web analytics to improve site design, by optimizing site structure, content, or technical specifications. However, participants also use web analytics to understand their audiences without a directed purpose, often for curiosity or entertainment. The design of web analytics tools should account for this full range of functionality.

In addition to storing a plethora of sensitive personal and work information, smartphones also store sensor data about users and their daily activities. In order to understand users' behaviors and attitudes towards the security of their smartphone data, we conducted 28 qualitative interviews. We examined why users choose (or choose not) to employ locking mechanisms (e.g., PINs) and their perceptions and awareness about the sensitivity of the data stored on their devices. We performed two additional online experiments to quantify our interview results and the extent to which sensitive data could be found in a user's smartphone-accessible email archive. We observed a strong correlation between use of security features and risk perceptions, which indicates rational behavior. However, we also observed that most users likely underestimate the extent to which data stored on their smartphones pervades their identities, online and offline.

Web browsers show HTTPS authentication warnings (i.e., SSL warnings) when the integrity and confidentiality of users' interactions with websites are at risk. Our goal in this work is to decrease the number of users who click through the Google Chrome SSL warning. Prior research showed that the Mozilla Firefox SSL warning has a much lower click-through rate (CTR) than Chrome. We investigate several factors that could be responsible: the use of imagery, extra steps before the user can proceed, and style choices. To test these factors, we ran six experimental SSL warnings in Google Chrome 29 and measured 130,754 impressions.

With so much of our lives digital, online, and not entirely under our control, we risk losing access to our communications, reputation, and data. Recent years have brought a rash of high-profile account compromises, but account hijacking is not limited to high-profile accounts. In this paper, we report results of a survey about people's experiences with and attitudes toward account hijacking. The problem is widespread; 30% of our 294 participants had an email or social networking account accessed by an unauthorized party. Five themes emerged from our results: (1) compromised accounts are often valuable to victims, (2) attackers are mostly unknown, but sometimes known, to victims, (3) users acknowledge some responsibility for keeping their accounts secure, (4) users' understanding of important security measures is incomplete, and (5) harm from account hijacking is concrete and emotional. We discuss implications for designing security mechanisms to improve chances for user adoption.

Sleep is a basic physiological process essential for good health. However, 40 million people in the U.S. are diagnosed with sleep disorders, with many more undiagnosed. To help address this problem, we developed an application, ShutEye, which provides a peripheral display on the wall-paper of the user's mobile phone to promote awareness about recommended activities that promote good sleep quality. Based on preferences about the user's desired bed-time and activities' for example - consuming caffeine or performing vigorous exercise - ShutEye displays guidance about when engaging in those activities is likely to affect sleep without requiring any explicit interaction from the user. In this paper, we describe ShutEye and results from a four-week field study with 12 participants. Results indicate that a simple, recommendation-based peripheral display can be a very low-effort but still effective method for improving awareness of healthy sleep habits. We also provide recommendations about designing peripheral displays and extend insights for designing health-based mobile applications.

In-home sensing and inference systems impose privacy risks and social tensions, which can be substantial barriers for the wide adoption of these systems. To understand what might affect people's perceptions and acceptance of in-home sensing and inference systems, we conducted an empirical study with 22 participants from 11 households. The study included in-lab activities, four weeks using sensor proxies in situ, and exit interviews. We report on participants' perceived benefits and concerns of in-home sensing applications and the observed changes of their perceptions throughout the study. We also report on tensions amongst stakeholders around the adoption and use of such systems. We conclude with a discussion on how the ubicomp design space might be sensitized to people's perceived concerns and tensions regarding sensing and inference in the home.

The bedroom environment can have a significant impact on the quality of a person's sleep. Experts recommend sleeping in a room that is cool, dark, quiet, and free from disruptors to ensure the best quality sleep. However, it is sometimes difficult for a person to assess which factors in the environment may be causing disrupted sleep. In this paper, we present the design, implementation, and initial evaluation of a capture and access system, called Lullaby. Lullaby combines temperature, light, and motion sensors, audio and photos, and an off-the-shelf sleep sensor to provide a comprehensive recording of a person's sleep. Lullaby allows users to review graphs and access recordings of factors relating to their sleep quality and environmental conditions to look for trends and potential causes of sleep disruptions. In this paper, we report results of a feasibility study where participants (N=4) used Lullaby in their homes for two weeks. Based on our experiences, we discuss design insights for sleep technologies, capture and access applications, and personal informatics tools.

Getting the right amount of quality sleep is a key aspect of good health, along with a healthy diet and regular exercise. Human-computer interaction (HCI) researchers have recently designed systems to support diet and exercise, but sleep has been relatively under-studied in the HCI community. We conducted a literature review and formative study aimed at uncovering opportunities for computing to support the important area of promoting healthy sleep. We present results from interviews with sleep experts, as well as a survey (N = 230) and interviews with potential users (N = 16) to indicate what people would find practical and useful for sleep. Based on these results, we identify a number of design considerations, challenges, and opportunities for using computing to support healthy sleep behaviors, as well as a design framework for mapping the design space of technologies for sleep.

New technologies for encouraging physical activity, healthy diet, and other types of health behavior change now frequently appear in the HCI literature. Yet, how such technologies should be evaluated within the context of HCI research remains unclear. In this paper, we argue that the obvious answer to this question - that evaluations should assess whether a technology brought about the intended change in behavior - is too limited. We propose that demonstrating behavior change is often infeasible as well as unnecessary for a meaningful contribution to HCI research, especially when in the early stages of design or when evaluating novel technologies. As an alternative, we suggest that HCI contributions should focus on efficacy evaluations that are tailored to the specific behavior-change intervention strategies (e.g., self-monitoring, conditioning) embodied in the system and studies that help gain a deep understanding of people's experiences with the technology.

As advances in technology accelerate, sensors and recording devices are increasingly being integrated into homes. Although the added benefit of sensing is often clear (e.g., entertainment, security, encouraging sustainable behaviors, etc.), the home is a private and intimate place, with multiple stakeholders who may have competing priorities and tolerances for what is acceptable and useful. In an effort to develop systems that account for the needs and concerns of householders, we conducted an anonymous survey (N = 475) focusing on the activities and habits that people do at home that they would not want to be recorded. In this paper, we discuss those activities and where in the home they are performed, and offer suggestions for the design of UbiComp systems that rely on sensing and recording.

Anyone within range of an 802.11 wireless network ("Wi-Fi") can use free software to collect the unencrypted web traffic of others on the network. However, many Wi-Fi users are completely unaware of the risk that this creates. This work aims to improve users' awareness about what they expose to others on Wi-Fi networks and provide them with some control. Our system, the Wi-Fi Privacy Ticker, displays information about the exposure of sensitive terms that are sent to and from a user's computer and prevents the unencrypted transmission of terms from the user's computer that she has identified as highly sensitive. In a three-week field study with 17 participants, we found that the Wi-Fi Privacy Ticker improved participants' awareness of the circumstances in which their personal information is transmitted. We show that this heightened awareness contributed to changes in their behavior while on Wi-Fi.

In this paper, we propose design strategies for persuasive technologies that help people who want to change their everyday behaviors. Our strategies use theory and prior work to substantially extend a set of existing design goals. Our extensions specifically account for social characteristics and other tactics that should be supported by persuasive technologies that target long-term discretionary use throughout everyday life. We used these strategies to design and build a system that encourages people to lead a physically active lifestyle. Results from two field studies of the system - a three-week trial and a three-month experiment - have shown that the system was successful at helping people maintain a more physically active lifestyle and validate the usefulness of the strategies.

The greatest contributor of CO2 emissions in the average American household is personal transportation. Because transportation is inherently a mobile activity, mobile devices are well suited to sense and provide feedback about these activities. In this paper, we explore the use of personal ambient displays on mobile phones to give users feedback about sensed and self-reported transportation behaviors. We first present results from a set of formative studies exploring our respondents' existing transportation routines, willingness to engage in and maintain green transportation behavior, and reactions to early mobile phone "green" application design concepts. We then describe the results of a 3-week field study (N=13) of the UbiGreen Transportation Display prototype, a mobile phone application that semi-automatically senses and reveals information about transportation behavior. Our contributions include a working system for semi-automatically tracking transit activity, a visual design capable of engaging users in the goal of increasing green transportation, and the results of our studies, which have implications for the design of future green applications.

Increasingly, users access online services such as email, e-commerce, and social networking sites via 802.11-based wireless networks. As they do so, they expose a range of personal information such as their names, email addresses, and ZIP codes to anyone within broadcast range of the network. This paper presents results from an exploratory study that examined how users from the general public understand Wi-Fi, what their concerns are related to Wi-Fi use, and which practices they follow to counter perceived threats. Our results reveal that while users understand the practical details of Wi-Fi use reasonably well, they lack understanding of important privacy risks. In addition, users employ incomplete protective practices which results in a false sense of security and lack of concern while on Wi-Fi. Based on our results, we outline opportunities for technology to help address these problems.

Goal-setting has been shown to be an effective strategy for changing behavior; therefore employing goal-setting in persuasive technologies could be an effective way to encourage behavior change. In our work, we are developing persuasive technologies to encourage individuals to live healthy lifestyles with a focus on being physically active. As part of our investigations, we have explored individuals' reactions to goal-setting, specifically goal sources (i.e., who should set the individual's goal) and goal timeframes (i.e., over what time period should an individual have to achieve the goal). In this paper, we present our findings related to various approaches for implementing goal-setting in a persuasive technology to encourage physical activity.

There is a pressing need for an effective means of transforming health behaviors. Obesity, anxiety and other behavior-generated health conditions result in billions of dollars of healthcare costs and a great deal of human suffering. Technology innovations are rapidly presenting new delivery mechanisms that can be harnessed to influence health behaviors.

Recent advances in small inexpensive sensors, low-power processing, and activity modeling have enabled applications that use on-body sensing and machine learning to infer people's activities throughout everyday life. To address the growing rate of sedentary lifestyles, we have developed a system, UbiFit Garden, which uses these technologies and a personal, mobile display to encourage physical activity. We conducted a 3-week field trial in which 12 participants used the system and report findings focusing on their experiences with the sensing and activity inference. We discuss key implications for systems that use on-body sensing and activity inference to encourage physical activity.

Personal, mobile displays, such as those on mobile phones, are ubiquitous, yet for the most part, underutilized. We present results from a field experiment that investigated the effectiveness of these displays as a means for improving awareness of daily life (in our case, self-monitoring of physical activity). Twenty-eight participants in three experimental conditions used our UbiFit system for a period of three months in their day-to-day lives over the winter holiday season. Our results show, for example, that participants who had an awareness display were able to maintain their physical activity level (even during the holidays), while the level of physical activity for participants who did not have an awareness display dropped significantly. We discuss our results and their general implications for the use of everyday mobile devices as awareness displays.

This paper presents MyExperience, a system for capturing both objective and subjective in situ data on mobile computing activities. MyExperience combines the following two techniques: 1) passive logging of device usage, user context, and environmental sensor readings, and 2) active context-triggered user experience sampling to collect in situ, subjective user feedback. MyExperience currently runs on mobile phones and supports logging of more than 140 event types, including: 1) device usage such as communication, application usage, and media capture, 2) user context such as calendar appointments, and 3) environmental sensing such as Bluetooth and GPS. In addition, user experience sampling can be targeted to moments of interest by triggering off sensor readings. We present several case studies of field deployments on people's personal phones to demonstrate how MyExperience can be used effectively to understand how people use and experience mobile technology.

To evaluate ubiquitous computing technologies, which may be embedded in the environment, embedded in objects, worn, or carried by the user throughout everyday life, it is essential to use methods that accommodate the often unpredictable, real-world environments in which the technologies are used. This article discusses how we have adapted and applied traditional methods from psychology and human-computer interaction, such as Wizard of Oz and Experience Sampling, to be more amenable to the in situ evaluations of ubiquitous computing applications, particularly in the early stages of design. The way that ubiquitous computing technologies can facilitate the in situ collection of self-report data is also discussed. Although the focus is on ubiquitous computing applications and tools for their assessment, it is believed that the in situ evaluation tools that are proposed will be generally useful for field trials of other technology, applications, or formative studies that are concerned with collecting data in situ.

Overweight and obesity are a global epidemic, with over one billion overweight adults worldwide (300+ million of whom are obese). Obesity is linked to several serious health problems and medical conditions. Medical experts agree that physical activity is critical to maintaining fitness, reducing weight, and improving health, yet many people have difficulty increasing and maintaining physical activity in everyday life. Clinical studies have shown that health benefits can occur from simply increasing the number of steps one takes each day and that social support can motivate people to stay active. In this paper, we describe Houston, a prototype mobile phone application for encouraging activity by sharing step count with friends. We also present four design requirements for technologies that encourage physical activity that we derived from a three-week long in situ pilot study that was conducted with women who wanted to increase their physical activity.

Advances in location-enhanced technology are making it easier for us to be located by others. These new technologies present a difficult privacy tradeoff, as disclosing one's location to another person or service could be risky, yet valuable. To explore whether and what users are willing to disclose about their location to social relations, we conducted a three-phased formative study. Our results show that the most important factors were who was requesting, why the requester wanted the participant's location, and what level of detail would be most useful to the requester. After determining these, participants were typically willing to disclose either the most useful detail or nothing about their location. From our findings, we reflect on the decision process for location disclosure. With these results, we hope to influence the design of future location-enhanced applications and services.

In this article, we describe the design process of Reno, a location-enhanced, mobile coordination tool and person finder. The design process included three field experiments: a formative Experience Sampling Method (ESM) study, a pilot deployment and an extended user study. These studies were targeted at the significant personal security, privacy and data protection concerns caused by this application. We distil this experience into a small set of guidelines for designers of social mobile applications and show how these guidelines can be applied to a different application, called Boise. These guidelines cover issues pertaining to personal boundary definition, control, deception and denial, and group vs. individual communication. We also report on lessons learned from our evaluation experience, which might help practitioners in designing novel mobile applications, including the choice and characterization of users for testing security and privacy features of designs, the length of learning curves and their effect on evaluation and the impact of peculiar deployment circumstances on the results of these finely tuned user studies.