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With an increasing number of technologies supporting transactions over distance and replacing traditional forms of interaction, designing for trust has become a core concern for researchers in both HCI and CMC. While much research focuses on increasing trust in mediated interactions, this paper takes a systemic view to identify the factors that support trustworthy behavior. In a second step, we analyze how the presence of these factors can be signaled to allow the formation of well-placed trust. For our analysis we draw on relevant research from sociology, economics, and psychology, as well as empirical findings in HCI and CMC research. The key factors that warrant trust in another actor are contextual properties (temporal, social, and institutional embeddedness) and the trusted actor's intrinsic properties (ability and motivation). In first interactions, trust is mainly warranted by contextual properties, as they provide external incentives and threat of punishment. As interactions are repeated over time and trust grows, intrinsic properties become more important. To increase the level of well-placed trust, researchers and designers need to identify signals for the presence of such trust-warranting properties that are reliable and easy to interpret. At the same time, they must be cheap to emit for actors whose actions are governed by them but costly to mimic for untrustworthy actors. Our analysis provides a frame of reference for the design of studies on trust in technology-mediated exchanges, as well as a guide for identifying trust requirements in design processes. We demonstrate application of the model in three scenarios: ecommerce, voice-enabled online gaming, and ambient technologies.

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In this paper we describe an experiment designed to investigate the importance of eye gaze in humanoid avatars representing people engaged in conversation. We compare responses to dyadic conversations in four mediated conditions: video, audio-only, and two avatar conditions. The avatar conditions differed only in their treatment of eye gaze. In the random-gaze condition the avatar's head and eye animations were unrelated to conversational flow. In the informed-gaze condition, they were related to turn-taking during the conversation. The head animations were tracked and the eye animations were inferred from the audio stream. Our comparative analysis of 100 post-experiment questionnaires showed that the random-gaze avatar did not improve on audio-only communication. The informed-gaze avatar significantly outperformed the random-gaze model and also outperformed audio-only on several response measures. We conclude that an avatar whose gaze behaviour is related to the conversation provides a marked improvement on an avatar that merely exhibits liveliness.

The aim of this paper is to establish a methodological foundation for Human-Computer Interaction (HCI) researchers aiming to assess trust between people interacting via computer-mediated communication (CMC) technology. The most popular experimental paradigm currently employed by HCI researchers are social dilemma games based on the Prisoner's Dilemma (PD), a technique originating from economics. HCI researchers employing this experimental paradigm currently interpret the rate of cooperation-measured in the form of collective pay-off-as the level of trust the technology allows its users to develop. We argue that this interpretation is problematic, since the game's synchronous nature models only very specific trust situations. Furthermore, experiments that are based on PD games cannot model the complexity of how trust is formed in the real world, since they neglect factors such as ability and benevolence. In conclusion, we recommend (a) means of improving social dilemma experiments by using asynchronous Trust Games, (b) collecting a broader range (in particular qualitative) data, and (c) increasing use of longitudinal studies.

Abstract-The computer security community has advocated widespread adoption of secure communication tools to counter mass surveillance. Several popular personal communication tools (e.g., WhatsApp, iMessage) have adopted end-to-end encryption, and many new tools (e.g., Signal, Telegram) have been launched with security as a key selling point. However it remains unclear if users understand what protection these tools offer, and if they value that protection. In this study, we interviewed 60 participants about their experience with different communication tools and their perceptions of the tools' security properties. We found that the adoption of secure communication tools is hindered by fragmented user bases and incompatible tools. Furthermore, the vast majority of participants did not understand the essential concept of end-to-end encryption, limiting their motivation to adopt secure tools. We identified a number of incorrect mental models that underpinned these beliefs.

To date, system research has focused on designing security mechanisms to protect systems access although their usability has rarely been investigated. This paper reports a study in which users' perceptions of password mechanisms were investigated through questionnaires and interviews. Analysis of the questionnaires shows that many users report problems, linked to the number of passwords and frequency of password use. In-depth analysis of the interview data revealed that the degree to which users conform to security mechanisms depends on their perception of security levels, information sensitivity and compatibility with work practices. Security mechanisms incompatible with these perceptions may be circumvented by users and thereby undermine system security overall.

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