The shelter-in-place orders across the U.S. in response to the COVID-19 pandemic forced many relationships once sustained by in-person interaction into remote states through computer-mediated communication (CMC). Work, school, holidays, social engagements, and everyday conversations formerly experienced through rich and contextual in-person interactions instead have taken place on messaging, voice, and video chatting platforms that diminish or altogether lack many social cues and other qualities critical to social interaction. The difficulties feeling connected to one another observed during this period have stressed the need for novel forms of communication that enable deeper interactions. Social biosensing, the interpersonal sharing of physiological information, has shown promise facilitating social connection at a distance. In the present research we document the experiences of nine pairs of friends (N = 18) who navigated living through a shelter-in-place order, reporting on their experiences sharing their electrodermal activity (EDA) in response to short videos. Participants described the artificial and unnatural nature of communicating using typical forms of CMC and a range of interpretations of EDA as both emotional response and as representative of personal characteristics. We implemented a phased approach to study the temporal nature of forming an understanding of unfamiliar yet intimate data like EDA. Our results indicate typologies of meaning-making processes: "stablers", "broadeners", and "puzzlers". We also interpreted our findings through the lens of intersubjectivity, analyzing how analogical apperception and dialogical interaction both play a role in participants' meaning-making about their own and their partner's biosensory information. We conclude with implications from this work pertinent to intersubjectivity theorists, social biosensing researchers, and CMC system designers and developers.

Algorithms engineered to leverage rich behavioral and biometric data to predict individual attributes and actions continue to permeate public and private life. A fundamental risk may emerge from misconceptions about the sensitivity of such data, as well as the agency of individuals to protect their privacy when fine-grained (and possibly involuntary) behavior is tracked. In this work, we examine how individuals adjust their behavior when incentivized to avoid the algorithmic prediction of their intent. We present results from a virtual reality task in which gaze, movement, and other physiological signals are tracked. Participants are asked to decide which card to select without an algorithmic adversary anticipating their choice. We find that while participants use a variety of strategies, data collected remains highly predictive of choice (80% accuracy). Additionally, a significant portion of participants became more predictable despite efforts to obfuscate, possibly indicating mistaken priors about the dynamics of algorithmic prediction.

Biosensors-devices that sense the human body-are increasingly ubiquitous. However, it is unclear how people evaluate the risks associated with their use, in part because it is not well-understood what people believe these sensors can reveal. In this study, participants ranked biosensors by how likely they are to reveal what a person is thinking and feeling. We report quantitative and qualitative results of two survey-based studies, one on Mechanical Turk workers (n=100), and one on participants in a longitudinal self-tracking study (n=100). Our findings imply that, in the absence of information about particular sensing technologies, people rely on existing beliefs about the body to explain what they might reveal. Highlighting mismatches between perceived and actual technical capabilities, we contribute recommendations for designers and users.

Digitally sharing our experiences engages a process of empathy shaped by available informational cues. Biosensory data is one informative cue, but the relationship to empathy is underexplored. In this study, we investigate this process by showing a video of a "target'' person's visual perspective watching a virtual reality film to sixty "observers''. We vary information available to observers via three experimental conditions: a baseline unmodified video, video with narrative text, or with a graph of electrodermal activity (EDA) of the target. Compared to baseline, narrative text increased empathic accuracy (EA) while EDA had an opposite, negative effect. Qualitatively, observers describe their empathic processes as using their own feelings supplemented with the information presented depending on the interpretability of that information. Both narration and EDA prompted observers to reconsider assumptions about another's experience. Our findings lead to a discussion of digitally-mediated empathy with implications for associated research and product development.

In this paper, we use design fiction to explore the social implications for adoption of brain-computer interfaces (BCI). We argue that existing speculations about BCIs are incomplete: they discuss fears about radical changes in types of control, at the expense of discussing more traditional types of power that emerge in everyday experience, particularly via labor. We present a design fiction in which a BCI technology creates a new type of menial labor, using workers' unconscious reactions to assist algorithms in performing a sorting task. We describe how such a scenario could unfold through multiple sites of interaction: the design of an API, a programmer's question on StackOverflow, an internal memo from a dating company, and a set of forum posts about laborers' experience using the designed system. Through these fictions, we deepen and expand conversations around what kinds of (everyday) futures BCIs could create.

We presented software engineers in the San Francisco Bay Area with a working brain-computer interface (BCI) to surface the narratives and anxieties around these devices among technical practitioners. Despite this group's heterogeneous beliefs about the exact nature of the mind, we find a shared belief that the contents of the mind will someday be "read' or "decoded' by machines. Our findings help illuminate BCI's imagined futures among engineers. We highlight opportunities for researchers to involve themselves preemptively in this nascent space of intimate biosensing devices, suggesting our findings' relevance to long-term futures of privacy and cybersecurity.

Emotional biosensing is rising in daily life: Data and categories claim to know how people feel and suggest what they should do about it, while CSCW explores new biosensing possibilities. Prevalent approaches to emotional biosensing are too limited, focusing on the individual, optimization, and normative categorization. Conceptual shifts can help explore alternatives: toward materiality, from representation toward performativity, inter-action to intra-action, shifting biopolitics, and shifting affect/desire. We contribute (1) synthesizing wide-ranging conceptual lenses, providing analysis connecting them to emotional biosensing design, (2) analyzing selected design exemplars to apply these lenses to design research, and (3) offering our own recommendations for designers and design researchers. In particular we suggest humility in knowledge claims with emotional biosensing, prioritizing care and affirmation over self-improvement, and exploring alternative desires. We call for critically questioning and generatively re-imagining the role of data in configuring sensing, feeling, 'the good life,' and everyday experience.

Passthoughts, in which a user thinks a secret thought to log in to services or devices, provides two factors of authentication (knowledge and inherence) in a single step. Since its proposal in 2005, passthoughts enjoyed a number of successful empirical studies. In this paper, we renew the promise of passthoughts authentication, outlining the main challenges that passthoughts must overcome in order to move from the lab to the real world. We propose two studies, which seek different angles at the fundamental questions we pose. Further, we propose it as a fruitful case study for thinking about what authentication can, and should, be expected to do, as it pushes up against questions of what sorts of "selves" authentication systems must be tasked with recognizing. Through this discussion, we raise novel possibilities for authentication broadly, such as "organic passwords" that change naturally over time, or systems that reject users who are not acting quite "like themselves."

Although "privacy by design" (PBD)?embedding privacy protections into products during design, rather than retroactively?uses the term "design" to recognize how technical design choices implement and settle policy, design approaches and methodologies are largely absent from PBD conversations. Critical, speculative, and value-centered design approaches can be used to elicit reflections on relevant social values early in product development, and are a natural fit for PBD and necessary to achieve PBD's goal. Bringing these together, we present a case study using a design workbook of speculative design fictions as a values elicitation tool. Originally used as a reflective tool among a research group, we transformed the workbook into artifacts to share as values elicitation tools in interviews with graduate students training as future technology professionals. We discuss how these design artifacts surface contextual, socially-oriented understandings of privacy, and their potential utility in relationship to other values levers.

While brain-computer interfaces (BCI) based on electroencephalography (EEG) have improved dramatically over the past five years, their inconvenient, head-worn form factor has challenged their wider adoption. In this paper, we investigate how EEG signals collected from the ear could be used for “gestural” control of a brain-computer interface (BCI). Specifically, we investigate the efficacy of a support vector classifier (SVC) in distinguishing between mental tasks, or gestures, recorded by a modified, consumer headset. We find that an SVC reaches acceptable BCI accuracy for nine of the subjects in our pool (n=12), and distinguishes at least one pair of gestures better than chance for all subjects. User surveys highlight the need for longer-term research on user attitudes toward in-ear EEG devices, for discreet, non-invasive BCIs.

Little is known about the affective expressivity of multisensory stimuli in wearable devices. While the theory of emotion has referenced single stimulus and multisensory experiments, it does not go further to explain the potential effects of sensorial stimuli when utilized in combination. In this paper, we present an analysis of the combinations of two sensory modalities - haptic (more specifically, vibrotactile) stimuli and auditory stimuli. We present the design of a wrist-worn wearable prototype and empirical data from a controlled experiment (N=40) and analyze emotional responses from a dimensional (arousal + valence) perspective. Differences are exposed between “matching” the emotions expressed through each modality, versus "mixing" auditory and haptic stimuli each expressing different emotions. We compare the effects of each condition to determine, for example, if the matching of two negative stimuli emotions will render a higher negative effect than the mixing of two mismatching emotions. The main research question that we study is: When haptic and auditory stimuli are combined, is there an interaction effect between the emotional type and the modality of the stimuli? We present quantitative and qualitative data to support our hypotheses, and complement it with a usability study to investigate the potential uses of the different modes. We conclude by discussing the implications for the design of affective interactions for wearable devices.

In open collaboration, knowledge is created and iteratively improved by a multitude of editors who freely choose what should be their contributions. The quality of knowledge artifacts (e.g. article, source code file) is deeply tied to their individual expertise, and to their ability to collaborate well. Conversely, the expertise of contributors is a function of artifacts contributed to. Building upon a large stream of literature on the measurement of article quality and contributor expertise, we propose a recursive algorithm to measure how editor expertise influences the quality of articles, and how contributions to articles influence editor expertise. This bi-partite network random walker metric reveals the specific structure of cooperation and how the quality of articles is achieved through coordination. We show that while the wisdom of crowds is well pulled in some categories, more editors per article can also create disvalue.

When engaged in ICTD research, it is often simpler to focus efforts on a single specific technology, whether that entails computers for telecenters, mobile phones for data collection, or text messages for public health education. In practice, however, people and organizations use a variety of technologies together, smoothly interweaving them as they navigate their lives. In this paper we analyze the ways in which a health financing organization in Uganda integrates a variety of communications technologies together to achieve reliable communications with their partnering health facilities distributed throughout Southwest Uganda. Based on four years of participant observation, we describe two communication scenarios in this organization to illustrate braided communications at work. We find that stakeholders work together to develop and maintain effective relationships using many different communications channels together in parallel, a combined channel we describe as braided communications. Braided communications have three primary characteristics. Firstly, they use co-existing channels, employing each as best suits a given set of goals. Secondly, they are co-dependent, or co-reinforcing, with strengths of individual channels reinforcing weaknesses of other channels. Finally, they are co-evolving; as available technologies and the ways in which they are used change, the nature of the braided use changes as well.

Does crowdsourcing work for web security? While the herculean task of evaluating hundreds of millions of websites can certainly benefit from the wisdom of crowds, skeptics question the coverage and reliability of inputs from ordinary users for assessing web security. We analyze the contribution patterns of serious and casual users in Web of Trust (WOT), a community-based system for website reputation and security. We find that the serious contributors are responsible for reporting and attending to a large percentage of bad sites, while a large fraction of attention on the goodness of sites come from the casual contributors. This complementarity enables WOT to provide warnings about malicious sites while differentiating the good sites from the unknowns. This in turn helps steer users away from the numerous bad sites created daily. We also find that serious contributors are more reliable in evaluating bad sites, but no better than casual contributors in evaluating good sites. We discuss design implications for WOT and for community-based systems more generally.

Computer users express a strong desire to prevent attacks and to reduce the losses from computer and information security breaches. However, security compromises are common and widespread and highly damaging. Next to attackers' increased sophistication, a root cause for the harm inflicted is that users often fail to optimally protect their resources or to recover gracefully from a security breach.

Despite general awareness of the importance of keeping one's system secure, and widespread availability of consumer security technologies, actual investment in security remains highly variable across the Internet population, allowing attacks such as distributed denial-of-service (DDoS) and spam distribution to continue unabated. By modeling security investment decision-making in established (e.g., weakest-link, best-shot) and novel games (e.g., weakest-target), and allowing expenditures in self-protection versus self-insurance technologies, we can examine how incentives may shift between investment in a public good (protection) and a private good (insurance), subject to factors such as network size, type of attack, loss probability, loss magnitude, and cost of technology. We can also characterize Nash equilibria and social optima for different classes of attacks and defenses. In the weakest-target game, an interesting result is that, for almost all parameter settings, more effort is exerted at Nash equilibrium than at the social optimum. We may attribute this to the "strategic uncertainty" of players seeking to self-protect at just slightly above the lowest protection level.

We propose an economic model based on user utility to study the adoption of new network architectures such as IPv6. We use mathematical analysis and simulation studies to understand the role of various factors such as user and network benefits, switching costs, and the impact of converters on the adoption of new network architectures. In addition to corroborating various commonly held beliefs about new network architecture adoption, our analysis and simulation studies also reveal several surprising and non-intuitive results. For example, while in general, increasing the efficiency of converters hastens the adoption of new network architectures, there are cases in which more efficient converters hinder the adoption of such architectures. This and other results in the paper increase our understanding of new network architecture adoption and guide the design and implementation of mechanisms to hasten new network architecture adoption.

The Valiant Load-Balancing (VLB) design has been proposed for a backbone network architecture that can efficiently provide predictable performance under changing traffic matrices [1]. In this paper we show that the VLB network hasoptimalperformance when nodes can fail, in the sense that it can support the maximal homogeneous flow for any number of node failures. We generalize the VLB design to enable interconnection of multiple VLB networks, and study interconnection via bilateral peering agreements as well as transit agreements. We show that using VLB as a transit scheme yields the lowest possible network and interconnection capacities, while VLB peering can also achieve near-optimal use of capacity.

In theory, multi homed Internet hosts, that is, hosts simultaneously connected to multiple Internet service providers (ISP) should see increased access capacity, be able to circumvent possible last-mile congestion problems, and experience improved end-to-end quality of service (QoS). In practice however, the advantages one can gain from multi homing are highly dependent on the path switching mechanism used, that is, on dynamically deciding which ISP should be used as a first-hop. This paper is a first step toward understanding the trade-off between performance improvements multi homing can help achieve and the complexity of the decisions that must be made. We measure changes in end-to-end network layer metrics (loss, latency, jitter) over the different paths available from a multi homed host to a large population of Internet hosts. Our measurements indicate that (1) in over 60% of the cases, one only needs to reevaluate the service provided by each ISP every minute to improve the performance of a specific metric, and that (2) in approximately 85% of the cases, decisions to switch from one ISP to another can be treated independently of the service metric of interest. We conclude that multi homing could in practice result in noticeable performance improvements.

In communication networks, such as the Internet or mobile ad-hoc networks, the actions taken by intermediate nodes or links are typically hidden from the communicating endpoints; all the endpoints can observe is whether or not the end-to-end transmission was successful. Therefore, in the absence of incentives to the contrary, rational (i.e., selfish) intermediaries may choose to forward messages at a low priority or simply not forward messages at all. Using a principal-agent model, we show how the hidden-action problem can be overcome through appropriate design of contracts in both the direct (the endpoints contract with each individual router directly) and the recursive (each router contracts with the next downstream router) cases. We further show that, depending on the network topology, per-hop or per-path monitoring may not necessarily improve the utility of the principal or the social welfare of the system.

Striping is a resource aggregation technique that can improve application performance for a multihomed host by utilizing multiple interfaces. In this position paper, we argue in favor of decoupling striping primitives from all of the traditional layers of the networking protocol stack, and instead resurrecting the session layer for striping. Session layer striping indeed allows applications to take advantage of multihoming, while avoiding most of the deployability issues traditionally linked with modiflying application layer code. We illustrate our argument with a strawman architecture for a session layer striping protocol, and sketch how such a protocol could be implemented.

Today's Internet industry suffers from several well-known pathologies, but none is as destructive in the long term as its resistance to evolution. Rather than introducing new services, ISPs are presently moving towards greater commoditization. It is apparent that the network's primitive system of contracts does not align incentives properly. In this study, we identify the network's lack of accountability as a fundamental obstacle to correcting this problem: Employing an economic model, we argue that optimal routes and innovation are impossible unless new monitoring capability is introduced and incorporated with the contracting system. Furthermore, we derive the minimum requirements a monitoring system must meet to support first-best routing and innovation characteristics. Our work does not constitute a new protocol; rather, we provide practical and specific guidance for the design of monitoring systems, as well as a theoretical framework to explore the factors that influence innovation.

We devise a model to study the phenomenon of free-riding and free-identities in peer-to-peer systems. At the heart of our model is a user of a certain type, an intrinsic and private parameter that reflects the user's willingness to contribute resources to the system. A user decides whether to contribute or free-ride based on how the current contribution cost in the system compares to her type. We study the impact of mechanisms that exclude low type users or, more realistically, penalize free-riders with degraded service. We also consider dynamic scenarios with arrivals and departures of users, and with whitewashers -users who leave the system and rejoin with new identities to avoid reputational penalties. We find that imposing penalty on all users that join the system is effective under many scenarios. In particular, system performance degrades significantly only when the turnover rate among users is high. Finally, we show that the optimal exclusion or penalty level differs significantly from the level that optimizes the performance of contributors only for a limited range of societal generosity levels.

We propose a service differentiated peer selection mechanism for peer-to-peer media streaming systems. The mechanism provides flexibility and choice in peer selection to the contributors of the system, resulting in high quality streaming sessions. Free-riders are given limited options in peer selection,if any, and hence receive low quality streaming. The proposed incentive mechanism follows the characteristics of rank-order tournaments theory that considers only the relative performance of the players, and the top prizes are awarded to the winners of the tournament. Using rank-order tournaments, we analyze the behavior of utility maximizing users. Through simulation and wide-area measurement studies, we verify that the proposed incentive mechanism can provide near optimal streaming quality to the cooperative users until the bottleneck shifts from the streaming sources to the network.

In this paper, we propose a cost-based model to evaluate the resources that each node has to contribute for participating in an overlay network. Such a cost model allows to gauge potential disincentives for nodes to collaborate, and provides a measure of the "total cost" of a network, which is a possible benchmark to distinguish between different network architectures. We characterize the cost imposed on a node as a parameterized function of the experienced load and of the node connectivity, and express benefits in terms of cost reductions. We discuss the notions of social optimum and Nash equilibrium with respect to the proposed cost model. We show that the social optimum may significantly deviate from a Nash equilibrium when nodes value the resources they use to forward traffic on behalf of other nodes. Through analytical and numerical results, we then use the proposed cost model to evaluate some of the topologies recently proposed for overlay networks, and to exhibit some of the challenges systems designers may face. We conclude by outlining some of the open questions this research has raised.

Residential multihoming provides path redundancy as well as path diversity that can be used to improve not just network availability, but also application-layer quality of service. The path diversity can be effectively utilized by a streaming application to achieve high quality streaming. We design a multipath multihoming media streaming system (MMS) that exploits the path diversity due to multihoming to improve the streaming quality. Through a series of experiments over the Internet, we show that MMS improves the quality of streaming sessions by more than 30% when connections are split over the available physical links and migrated from one path to another to avoid congested paths.

Copyright holders have been investigating technological solutions to prevent distribution of copyrighted materials in peer-to-peer file sharing networks. A particularly popular technique consists in "poisoning" a specific item (movie, song, or software title) by injecting a massive number of decoys into the peer-to-peer network, to reduce the availability of the targeted item. In addition to poisoning, pollution, that is, the accidental injection of unusable copies of files in the network, also decreases content availability. In this paper, we attempt to provide a first step toward understanding the differences between pollution and poisoning, and their respective impact on content availability in peer-to-peer file sharing networks. To that effect, we conduct a measurement study of content availability in the four most popular peer-to-peer file sharing networks, in the absence of poisoning, and then simulate different poisoning strategies on the measured data to evaluate their potential impact. We exhibit a strong correlation between content availability and topological properties of the underlying peer-to-peer network, and show that the injection of a small number of decoys can seriously impact the users' perception of content availability.

In multi-hop networks, the actions taken by individual intermediate nodes are typically hidden from the communicating endpoints; all the endpoints can observe is whether or not the end-to-end transmission was successful. Therefore, in the absence of incentives to the contrary, rational (i.e., selfish) intermediate nodes may choose to forward packets at a low priority or simply not forward packets at all. Using a principal-agent model, we show how the hidden-action problem can be overcome through appropriate design of contracts, in both the direct (the endpoints contract with each individual router) and recursive (each router contracts with the next downstream router) cases. We further demonstrate that per-hop monitoring does not necessarily improve the utility of the principal or the social welfare in the system. In addition, we generalize existing mechanisms that deal with hidden-information to handle scenarios involving both hidden-information and hidden-action.

We design a tree-based forward digest protocol (TFDP) to verify data integrity in distributed media streaming for content distribution. Several challenges arise, including the timing constraint of streaming sessions, the involvement of multiple senders, and the untrustworthiness of these senders. A comprehensive comparison is presented on the performance of existing protocols and TFDP, with respect to communication and computation overhead. Both simulation and Internet-based experimental results are presented to demonstrate the effectiveness of TFDP.

We propose a rank-based peer-selection mechanism for peer-to-peer media streaming systems. The mechanism provides incentives for cooperation through service differentiation. Contributors to the system are rewarded with flexibility and choice in peer selection, resulting in high quality streaming sessions. Free-riders are given limited options in peer selection, if any, and hence receive low quality streaming. Through simulation and wide-area measurement studies, we verify that the mechanism can provide near optimal streaming quality to the cooperative users until the bottleneck shifts from the sources to the network.

Lack of cooperation (free riding) is one of the key problems that confronts today's P2P systems. What makes this problem particularly difficult is the unique set of challenges that P2P systems pose: large populations, high turnover, a symmetry of interest, collusion, zero-cost identities, and traitors. To tackle these challenges we model the P2P system using the Generalized Prisoner's Dilemma (GPD),and propose the Reciprocative decision function as the basis of a family of incentives techniques. These techniques are fullydistributed and include: discriminating server selection, maxflow-based subjective reputation, and adaptive stranger policies. Through simulation, we show that these techniques can drive a system of strategic users to nearly optimal levels of cooperation.

The current Web caching infrastructure, though it has a number of performance benefits for clients and network providers, does not meet publishers' requirements. We argue that to satisfy these requirements, caches should be enhanced in both the data and control planes. In the data plane, caches will dynamically generate content for clients by running code provided by publishers. In the control plane, caches will return logs of client accesses to publishers. In this paper, we introduce Gemini, a system which has both of these capabilities, and discuss two of its key components: security and incremental deployment. Since Gemini caches are deeply involved in content preparation and logging, ensuring that they perform correctly is vital. Traditional end-to-end security mechanisms are not sufficient to protect clients and publishers, so we introduce a new security model which consists of two pieces: an authorization mechanism and a verification mechanism. The former allows a publisher to authorize a set of caches to run its code and serve its content, while the latter allows clients and publishers to probabilistically verify that authorized caches are operating correctly. Because it is unrealistic to assume that Gemini caches will be deployed everywhere simultaneously, we have designed the system to be incrementally deployable and to coexist with legacy clients, caches, and servers. Finally, we describe our implementation of Gemini and present preliminary performance results.

Summary form only given. Emerging caching techniques such as differential caching, push caching, etc enable preferential treatment of premium objects in a cache. By the use of appropriate placement, replacement or reporting policies, a service provider can offer multiple levels of QoS for different objects. For example, certain objects may be assigned higher priorities and be placed in a premium cache before they get pushed into the regular cache to increase their lifetime in the cache. Similar techniques open avenues for a service provider such as an IAP (Internet Access Provider) to offer several quality-differentiated services to content publishers at different prices and thus maximize revenues. We focus on the optimal pricing strategy of a caching service provider offering multiple quality levels. We analyze trade-offs between bandwidth savings and the potential to charge publishers for caching their content. We determine the optimum number of quality levels to offer and motivate a means for determining optimal allocation of the cache space among the different service classes.

The authors describe a method for fully distributed authentication using public key cryptography within the Kerberos ticket framework. By distributing most of the authentication workload away from the trusted intermediary and to the communicating parties, significant enhancements to security and scalability can be achieved as compared to Kerberos V5. Privacy of Kerberos clients is also enhanced. A working implementation of this extended protocol has been developed, and a migration plan is proposed for a transition from traditional to public key based Kerberos.