Critics have argued that mobile usability has largely been optimized, and that only incremental gains are possible. We set out to explore if the newest generation of design systems, which promote greater flexibility and a return to design basics, could produce substantially more usable designs while maintaining or increasing aesthetic judgments. Through a study with 48 diverse participants completing tasks in 10 different applications, we found that in designs created following Material 3 Expressive guidelines, users fixated on the correct screen element for a task 33% faster, completed tasks 20% faster, and rated experiences more positively compared to versions designed using the previous Material design system. These improvements in performance and aesthetic ratings challenge the premise of a usability plateau and show that mobile usability has not peaked. We illustrate specific opportunities to make mobile experiences more usable by returning to design fundamentals while highlighting risks of added flexibility.

Recent advances in general-purpose AI underscore the urgent need to align AI systems with human goals and values. Yet, the lack of a clear, shared understanding of what constitutes "alignment" limits meaningful progress and cross-disciplinary collaboration. In this position paper, we argue that the research community should explicitly define and critically reflect on "alignment" to account for the bidirectional and dynamic relationship between humans and AI. Through a systematic review of over 400 papers spanning HCI, NLP, ML, and more, we examine how alignment is currently defined and operationalized. Building on this analysis, we introduce the Bidirectional Human-AI Alignment framework, which not only incorporates traditional efforts to align AI with human values but also introduces the critical, underexplored dimension of aligning humans with AI – supporting cognitive, behavioral, and societal adaptation to rapidly advancing AI technologies. Our findings reveal significant gaps in current literature, especially in long-term interaction design, human value modeling, and mutual understanding. We conclude with three central challenges and actionable recommendations to guide future research toward more nuanced, reciprocal, and human-AI alignment approaches.

Scholars, journalists, and other commentators argue that many parts of the world, including the US, are suffering a social-epistemological crisis, sometimes called "post-truth," and that this crisis is related to the fragmentation of newsmedia. The conventional media effects research explanation for this relationship between news and "post-truth" is framed in terms of messages and information-especially misinformation-as the mechanism by which communication effects change. Analysing the results of a large (n = 164) interview study on mobile and other digital news audiencehood, this article presents an alternative, complementary explanation focused on ritual functions of communication. The primary method of affinity analysis of interview data identified a number of recurring themes: people's preferences, methods, and patterns of news consumption exhibit wild diversity beyond easy summary, but they share the experience of news as nearly ubiquitous, and often as excessive and therefore in need of management. Strategies for managing news broadly fell into categories of news avoidance and active research. Perhaps the most consistent observation across participants' accounts, however, is a conspicuous absence of other people, with news managed and confronted alone. Those findings are interpreted through James Carey's ritual theory of communication, which argues that meaning emerges not only through transmission of messages and information, but also through people's shared experiences of participating in the ritual processes of communication. This work makes a parallel argument that media fragmentation has been implicated in social-epistemological breakdown not only through the mechanism of messages and (mis)information, but also through the transformation and, in certain cases, loss of shared news rituals. The combination of large-scale interview research with media ritual analysis led to these insights about the cultural relevance and collective implications of people's experiences of ubiquitous news and the avoidance thereof.

Over three billion people use personal email accounts for a wide variety of communications, largely from businesses. These messages often require additional information that users need to look for outside of the email itself, such as store hours, bill details, or related news articles. We studied these "email-prompted information needs" in a pilot interview-based study, a two-week diary study, and a large-scale survey with 790 total participants, finding that Notification, Deal, and Newsletter messages were the most likely to spark a need for external information. We conclude with several designs evaluated in a concept evaluation study with 276 participants and implications for the design of personal email services to better meet users' external information needs.

A common practice in HCI research is to conduct a survey to understand the generalizability of findings from smaller-scale qualitative research. These surveys are typically deployed to convenience samples, on low-cost platforms such as Amazon's Mechanical Turk or Survey Monkey, or to more expensive market research panels offered by a variety of premium firms. Costs can vary widely, from hundreds of dollars to tens of thousands of dollars depending on the platform used. We set out to understand the accuracy of ten different survey platforms/panels compared to ground truth data for a total of 6,007 respondents on 80 different aspects of demographic and behavioral questions. We found several panels that performed significantly better than others on certain topics, while different panels provided longer and more relevant open-ended responses. Based on this data, we highlight the benefits and pitfalls of using a variety of survey distribution options in terms of the quality, efficiency, and representative nature of the respondents and the types of responses that can be obtained.

Despite claims of Mobile TV's mainstream arrival in 2010, it took until 2017 for watching professionally-produced television content on mobile phones to truly become a mass-market phenomenon in America, with half of all TV content expected to be watched on mobile phones by 2020. But what professionally produced content are people watching on their phones and when are they watching it? Are there any clusters of behavior that emerge in the broader population when it comes to watching TV on the phone? We set out to answer these questions through two surveys deployed to representative samples of online Americans. We discuss our findings on the mass-market arrival of mobile TV viewing and differences from how the HCI community has previously envisioned mobile video. We conclude with implications for the design of future mobile TV systems.

The news landscape has been changing dramatically over the past few years. Whereas news once came from a small set of highly edited sources, now people can find news from thousands of news sites online, through a variety of channels such as web search, social media, email newsletters, or direct browsing. We set out to understand how Americans read news online using web browser logs collected from 174 diverse participants. We found that 20% of all news sessions started with a web search, that 16% started from social media, that 61% of news sessions only involved a single news domain, and that 47% of our participants read news from both sides of the political spectrum. We conclude with key implications for online news, social media, and search sites to encourage more balanced news browsing.

Voice has become a widespread and commercially viable interaction mechanism with the introduction of voice assistants (VAs), such as Amazon’s Alexa, Apple’s Siri, Google Assistant, and Microsoft’s Cortana. Despite their prevalence, we do not have a detailed understanding of how these technologies are used in domestic spaces. To understand how people use VAs, we conducted interviews with 19 users, and analyzed the log files of 82 Amazon Alexa devices, totaling 193,665 commands, and 88 Google Home Devices, totaling 65,499 commands. In our analysis, we identified music, search, and IoT usage as the command categories most used by VA users. We explored how VAs are used in the home, investigated the role of VAs as scaffolding for Internet of Things device control, and characterized emergent issues of privacy for VA users. We conclude with implications for the design of VAs and for future research studies of VAs.

In recent years, online education's reach and scale have increased through new platforms for large and small online courses. However, these platforms often rely on impoverished modalities, which provide limited support for participation in social learning experiences. We present Collaborative Live Media Curation (CLMC), a new medium for sharing context and participation in online learning. CLMC involves collaborative, synchronous collection, creation, and assemblage of web media, including images, text, video, and sketch. CLMC integrates live media including streaming video, screenshares, audio, and text chat. We deploy and study LiveMâché, a CLMC technology probe, in four situated online learning contexts. We discovered student and instructor strategies for sharing context and participating including creating curations in advance, sketching to illustrate and gesture, real-time transformations, sharing perspective, and assembling live streams. We develop implications through live experience patterns, which describe how spatial and computing structures support social activities.

There are currently a wide variety of ways to share news with others: from sharing in a personal message, to sharing on a social network, to publicly posting. Through a survey with over one thousand people and an artifact analysis of 262 shared articles, we examine differences in motivations and frequency of sharing news on public, social and private platforms. We find that public sharing is more focused on spreading an ideology, while private sharing in messaging is dominated by stories inspired by the recipient's interests or context. The survey revealed three main groups of news sharing practices: those who shared to all channels (public, social, private), those who didn't share at all, and those who shared to private and social. The groups differed in their attitudes toward online discussion; those that shared the most were neutral and those that didn't share had negative attitudes about discussion online. We discuss sharing practices and implications for social systems that support sharing news.

Mobile videochat use has been growing, especially for teens. To better understand teens' videochat practices, we conducted a two-week photo diary study with 16 teens. We found that most often, teens videochat with their closest friends from their bedrooms when they feel lonely or bored. Teens turned to videochat when understimulated but also felt understimulated during videochat. In order to manage this, they multitasked -teens moved from active chatting to co-presence while engaged in separate activities like scrolling social feeds or playing games. We uncovered social norms of reciprocity of attention, where teens match the attention level of the other and give leeway to briefly divert attention. Digital notifications did not feel disruptive to the videochat but family members' interruptions felt disruptive as teens' domestic context intruded into their virtual peer setting. We discuss these findings and their implications for research and design of videochat systems.

Much of the existing research literature on email use focuses on productivity or work settings. However, personal use of email has rarely been studied in depth. With the growth of messaging platforms being used for an increasing amount of personal communication, yet email use remaining high, we were interested in learning what Americans are using email for in their daily lives in 2016. To explore this topic, we use qualitative data from over 150 interviews with personal email users as well as quantitative data from several larger survey-based studies. We will show that personal email use is very different from what has been previously studied by workplace researchers and that daily use is largely focused on receiving and viewing B2C messages such as coupons, deals, receipts, and event notifications with personal communication over email diminished to a rarer, less-than-daily occurrence. We discuss the implications of this for the design of email and communications clients and present a design and prototype for an application that seeks to support these more frequent uses of consumer email.

Previous work creating systems for collaborative search has mainly focused on solutions for the desktop. However, as the majority of web use moves to mobile phones, few systems have been created on this platform to support collaboration around search results. Mobile search is often a collaborative activity where the input of a group is sought before making a decision to purchase something, visit a venue, or book a ticket. However, currently search and messaging applications are separate, creating frustrating copy-and-paste interactions and uninformative blue links or OpenGraph cards in messages. We built the Search Messenger system to support both finding and sharing search results, in the form of rich, interactive cards, directly within a mobile messaging system. After building the system, we conducted a two-week field study exploring how 14 participants used the system in their daily lives. We report on our findings and implications for future mobile applications that embed functionality in messaging.

Mobile livestreaming is now well into its third wave. From early systems such as Bambuser and Qik, to more popular apps Meerkat and Periscope, to today's integrated social streaming features in Facebook and Instagram, both technology and usage have changed dramatically. In this latest phase of livestreaming, cameras turn inward to focus on the streamer, instead of outwards on the surroundings. Teens are increasingly using these platforms to entertain friends, meet new people, and connect with others on shared interests. We studied teens' livestreaming behaviors and motivations on these new platforms through a survey completed by 2,247 American livestreamers and interviews with 20 teens, highlighting changing practices, teens' differences from the broader population, and implications for designing new livestreaming services.

With recent shifts from email to messaging apps for personal communication, many communication partners are no longer able to converse using multiple threads within one platform as they used to via email. Romantic couples are the most frequently messaged contacts on mobile and communicate about a wide range of topics with each other, need to make joint decisions, and may have several roles in relation to each other (e.g., spouse, co-parent). Through a 3-week field study with ten U.S. diverse couples we studied how couples use a messaging app that allows them to compartmentalize their conversations into multiple "channels" around topics of their choice. We detail how couples managed and used channels in daily life, and channels' strengths and limitations. We found that channels made couples feel more organized, and helped with finding content and keeping track of topics. However, it was sometimes difficult to choose or navigate channels. We discuss perceived impacts of channels on relationships (e.g., topic-switching during conflicts), and outline design opportunities for messaging apps.

Temporal terms, such as 'winter', 'Christmas', or 'January' are often used in search queries for personal images. But how do people's memories and perceptions of time match with the actual dates when their images were captured? We compared the temporal terms that 74 Flickr users used to search their own photo collections, and compared them to the date captured data in the target image. We also conducted a larger study across several billion images, comparing user-applied tags for holidays and seasons to the dates the images were captured. We demonstrate that various query terms and tags can be in conflict with the actual dates photos were taken for specific types of temporal terms up to 40% of the time. We will conclude by highlighting implications for search systems where users are querying for personal content by date.

The use of applications on mobile devices has changed dramatically over the past few years. While web browsing was once a common activity, it's now reported that 86% of time on mobile phones is in apps other than the browser. We set out to understand how the mobile web was currently fitting into people's lives and what web sessions looked like. Finding a dramatic reduction in mobile web revisi-tation rates compared to previous work and that a large number of sessions comprised single page views, we then studied how web content was shared with others in mobile messaging, the source of many single page sessions. The HCI community has not heavily studied this sharing activity that many people perform daily. We conclude with design implications for new mobile applications from our two studies with a combined 287 participants where we studied actual logs of mobile web use and link sharing behavior.

We explore the use of a new way to log into a web service, such as email or social media. Using on-demand biometrics, users sign in from a browser on a computer using just their name, which sends a request to their phone for approval. Users approve this request by authenticating on their phone using their fingerprint, which completes the login in the browser. On-demand biometrics thus replace passwords or temporary access codes found in two-step verification with the ease of use of biometrics. We present the results of an interview study on the use of on-demand biometrics with a live login backend. Participants perceived our system as convenient and fast to use and also expressed their trust in fingerprint authentication to keep their accounts safe. We motivate the design of on-demand biometrics, present an analysis of participants' use and responses around general account security and authentication, and conclude with implications for designing fast and easy cross-device authentication.

Over the past decade, the mobile phonebook has evolved from a relatively short list of people that one calls and texts to a many-hundred person list of aggregated contacts from around the web. This is happening at a time when an increasing number of mobile applications are relying on the mobile phonebook to create one's social network in their services. Through a large-scale study of the phonebooks of 200 diverse participants, containing 65,940 contacts, we set out to understand today's mobile contact lists. Our participants reported that they did not recognize the names of 29% of their contacts and we found that the most frequently contacted five contacts represent greater than 80% of all calls and text messages with phonebook contacts. We conclude with implications for the design of mobile applications that rely on phonebook data.

We explore the everyday use of a new abstraction for mo-bile location-sharing. By sharing the travel time between contacts calculated for walking, transit, and driving, we have enabled users to more easily coordinate meeting up and planning family obligations. Specifically, our participants reported that the information helped to lower the stress of these activities and provided reassurance of the arrival times of their close friends and family. In this paper, we describe our system, motivate its design, and explore results from a 20-user, 21-day field trial showing the use-fulness of the abstraction as well as attitudes towards privacy when sharing travel times with close friends or family.

Today's smartphones enable rich, media-enhanced conversations. Millions of photos and billions of messages are shared each day on smartphones. But how, exactly, are images and web links being used in mobile conversations? And what does this mean for the design of new mobile communications applications? We set out to learn how people currently share and discuss mobile media by performing a detailed content analysis of 109 photos and links that were shared in 2,779 messages using a mobile messaging application deployed in the United State and Taiwan. Through our analysis of these conversations, we show how mobile media is used to experience the moment together, to fill in the visual details, to provide background context, and to exchange information. We then discuss our results and provide two designs inspired by our findings.

In this paper, we explore motivations for live-tweeting across a season of a television show. Using the third season of Downton Abbey as a case study, we followed 2,234 live-tweeters from the show's premiere episode to its finale, finding that nearly a third of users returned each week to tweet. Semi-structured interviews with 11 diverse live-tweeters revealed that the decision to live-tweet is dependent upon a variety of personal considerations and social conventions forming around this emerging TV viewing practice. This includes the desire to feel connected to a larger community that is interested in the show. Participants actively sought to protect the user experience of others by following good live-tweeting "etiquette", including limiting their number of posts and censoring content that might spoil the show for others. Over time, live-tweeting helped users build and maintain a network of fellow Downton Abbey viewers with shared interests.

Self-logging is a critical component to many wellbeing systems. However, self-logging often is difficult to sustain at regular intervals over many weeks. We demonstrate the power of passive mobile notifications to increase logging of wellbeing data, particularly food intake, in a mobile health service. Adding notifications increased the frequency of logging from 12% in a one-month, ten-user pilot study without reminders to 63% in the full 60-user study with reminders included. We will discuss the benefits of passive notifications over existing interruptive methods.

With the launch of 'app stores' on several mobile platforms and the great uptake of smartphones among the general population, researchers have begun utilising these distribution channels to deploy research software to large numbers of users. Previous Research In The Large workshops have sought to establish base-line practice in this area. We have seen the use of app stores as being successful as a methodology for gathering large amounts of data, leading to design implications, but we have yet to explore the full potential for this data's use and interpretation. How is it possible to leverage the practices of large-scale research, beyond the current approaches, to more directly inform future designs? We propose that the time is right to re-energise discussions on large-scale research, looking further than the basic methodological issues and assessing the potential for informing the design of new mobile software.

People now have access to many sources of data about their health and wellbeing. Yet, most people cannot wade through all of this data to answer basic questions about their long-term wellbeing: Do I gain weight when I have busy days? Do I walk more when I work in the city? Do I sleep better on nights after I work out? We built the Health Mashups system to identify connections that are significant over time between weight, sleep, step count, calendar data, location, weather, pain, food intake, and mood. These significant observations are displayed in a mobile application using natural language, for example, “You are happier on days when you sleep more.” We performed a pilot study, made improvements to the system, and then conducted a 90-day trial with 60 diverse participants, learning that interactions between wellbeing and context are highly individual and that our system supported an increased self-understanding that lead to focused behavior changes.

In building location-based services, it is important to present information in ways that fit with how individuals view and navigate the city. We conducted an adaptation of the 1970s Mental Maps study by Stanley Milgram in order to better understand differences in people's views of the city based on their backgrounds and technology use. We correlated data from a demographic questionnaire with the map data from our participants to perform a first-of-its-kind statistical analysis on differences in hand-drawn city maps. We describe our study, findings, and design implications for location-based services.

Diabetes patients adjust their insulin injections according to their food consumption, physical activity and glucose levels. These adjustments are often trial-and-error, and newly diagnosed patients often use logbooks to catalog their daily activities and aid their physicians in developing an appropriate regimen.

We describe the design and field evaluation of the Serendipitous Family Stories system, a web and mobile service that allows for videos to be saved in user-specified real-world locations, shared with friends and family, and then serendipitously discovered as those people approach the location of a story. Through a twenty-participant field evaluation, we discovered how this new form of location-based asynchronous communication can be used to strengthen family relationships by encouraging communication across generations and enhancing users' relationships with everyday places in their lives.

With the proliferation of app stores and the advancement of mobile devices, research that might have only been tested with a dozen participants in the past can now be released to millions. This offers huge opportunities, but also requires adaptations of existing methods in dealing with large deployments and making sense of large data sets. This workshop provides a forum for researchers to exchange experiences and strategies for wide distribution of applications as well as gathering and analyzing large scale data sets.

Mobile devices are now able to connect to a variety of sensors and provide personalized information to help people reflect on and improve their health. For example, pedometers, heart-rate sensors, glucometers, and other sensors can all provide real-time data to a variety of devices. Collecting and interacting with personal health or well-being data is a growing research area. This workshop will focus on the ways in which our mobile devices can aggregate and visualize these types of data and how these data streams can be presented to encourage interaction, increased awareness and positive behavior change.

We describe the TuVista system, a service for viewing near-live sports content consisting of a multimedia editing/bundling station, a cloud-hosted metadata server, and a set of mobile clients. We begin by introducing TuVista I, a proof of concept experience prototype implemented quickly as a probe to understand multimedia needs at a live sporting event. After discussing the results of an initial field trial at Estadio Azteca in Mexico City, we describe the improvements in TuVista II to address the issues identified. These include rapid editing of multiple live video streams, push notifications of new content over XMPP, and an optimized metadata workflow for the content producer that reduced content publication time from fifteen minutes to less than 30 seconds. We conclude with a discussion of rapid prototyping and field deployments as a way to quickly identify user needs.

We examine how ambient displays can augment social television. Social TV 2 is an interactive television solution that incorporates two ambient displays to convey to participants an aggregate view of their friends' current TV-watching status. Social TV 2 also allows users to see which television shows friends and family are watching and send lightweight messages from within the TV-viewing experience. Through a two-week field study we found the ambient displays to be an integral part of the experience. We present the results of our field study with a discussion of the implications for future social systems in the home.

We report on a field evaluation of a prototype social television system (Social TV) that incorporates lightweight messaging as well as ambient awareness of user presence on the system. This evaluation was conducted over a two-week period and involved the participation of ten households. Participants appreciated the ability to see their buddies' presence on the system, the ability to see or suggest the programs they were currently watching, and the ability to send short messages to one another. The presence facilities available in Social TV also allowed participants to learn more about one another's TV viewing habits and preferences, and fostered a sense of connectedness between them. However, they also felt constrained by the limitations of the communication options available to them and demanded free-form text or voice chat to be able to fully express themselves.

We present the Motion Presence application, an augmented phone book style application that allows close friends and family to view each other's current motion status ("moving" or "not moving") on their mobile phones. We performed a two week long field trial with 10 participants to observe usage and investigate any privacy concerns that might arise. We found that our participants used the motion information to infer location and activity as well as to plan communication, to help in coordinating in-person get-togethers, and to stay connected to patterns in each others' lives. Participants saw the motion data as mostly confirming their existing thoughts about the locations and activities of others and expressed few privacy concerns. In fact, they frequently asked for more information to be shared to make the application more compelling.

We describe the results of two ethnographic-style studies that investigated consumer use of photos and music respectively. Although the studies were designed, executed, and analyzed separately, in our findings we discovered striking similarities between the ways in which our participants used personally captured photos and commercially purchased music. These findings have implications for the design of future systems with respect to handling and sharing content in photo or music form. We discuss making allowances for satisficing behavior, sharing media as a way to reminisce or to communicate an experience (tell a story), getting sidetracked while browsing, and similarities in organizing behaviors.

The increasing capability of mobile handsets, advancing multimedia processing, improving codec technology (e.g., mp3, JPEG, MPEG-4 SP, H.264), and bigger communication pipes have the potential for providing increasing volumes of multimedia data to mobile users. The problem of intelligently managing multimedia content is becoming increasingly prevalent in this space. For example, applications that archive and retrieve personal content as well as those that search and stream commercial content over wired and wireless channels need to provide a compelling user experience while transparently and efficiently handling the vast amounts of underlying data. This work provides a user-intuitive, standards-based approach for managing multimedia content on mobile handsets.