This paper examines how social networks can be used to recruit and promote a crowdsourced citizen science project and compares this recruiting method to the use of tradition-al media channels including press releases, news stories, and participation campaigns. The target studied is Creek Watch, a citizen science project that allows anyone with an iPhone to submit photos and observations of their local waterways to authorities who use the data for water management, environmental programs, and cleanup events. The results compare promotional campaigns using a traditional press release with news pickups, a participation campaign through local organizations, and a social networking campaign through Facebook and Twitter. Results also include the trial of a feature that allows users to post automatically to Facebook or Twitter. Social networking is found to be a worthwhile avenue for increasing awareness of the project, increasing the conversion rate from browsers to participants, but that targeting existing communities with a participation campaign was a more successful means for increasing the amount of data collected by volunteers.

Citizen science projects can collect a wealth of scientific data, but that data is only helpful if it is actually used. While previous citizen science research has mostly focused on designing effective capture interfaces and incentive mechanisms, in this paper we explore the application of HCI methods to ensure that the data itself is useful. To provide a focus for this exploration we designed and implemented Creek Watch, an iPhone application and website that allow volunteers to report information about waterways in order to aid water management programs. Working with state and local officials and private groups involved in water monitoring, we conducted a series of contextual inquiries to uncover what data they wanted, what data they could immediately use, and how to most effectively deliver that data to them. We iteratively developed the Creek Watch application and website based on our findings and conducted evaluations of it with both contributors and consumers of water data, including scientists at the city water resources department. Our study reveals that the data collected is indeed useful for their existing practices and is already in use in water and trash management programs. Our results suggest the application of HCI methods to design the data for the end users is just as important as their use in designing the user interface.

The rapid increase in smart phone capabilities has introduced new opportunities for mobile information access and computing. However, smart phone use may still be constrained by both device affordances and work environments. To understand how current business users employ smart phones and to identify opportunities for improving business smart phone use, we conducted two studies of actual and perceived performance of standard work tasks. Our studies involved 243 smart phone users from a large corporation. We intentionally chose users who primarily work with desktops and laptops, as these "non-mobile" users represent the largest population of business users. Our results go beyond the general intuition that smart phones are better for consuming than producing information: we provide concrete measurements that show how fast reading is on phones and how much slower and more effortful text entry is on phones than on computers. We also demonstrate that security mechanisms are a significant barrier to wider business smart phone use. We offer design suggestions to overcome these barriers.

Browsing a collection of information on a mobile device is a common task, yet it can be difficult due to the small size of mobile displays. A common trade-off offered by many current mobile interfaces is to allow users to switch between an overview and detailed views of particular items. An open question is how much preview of each item to include in the overview. Using a mobile email processing task, we attempted to answer that question. We investigated participants' email processing behaviors under differing preview conditions in a semi-controlled, naturalistic study. We collected log data of participants' actual behaviors as well as their subjective impressions of different conditions. Our results suggest that a moderate level of two to three lines of preview should be the default. The overall benefit of a moderate amount of preview was supported by both positive subjective ratings and fewer transitions between the overview and individual items.

The primary goal of the Midas project is to build a system that enables easy and scalable integration of unstructured and semi-structured information present across multiple data sources. As a first step in this direction, we have built a system that extracts and integrates information from regulatory filings submitted to the U.S. Securities and Exchange Commission (SEC) and the Federal Deposit Insurance Corporation (FDIC). Midas creates a repository of entities, events, and relationships by extracting, conceptualizing, integrating, and aggregating data from unstructured and semi-structured documents. This repository enables applications to use the extracted and integrated data in a variety of ways including mashups with other public data and complex risk analysis.

The number of computing devices that people use is growing. To gain a better understanding of why and how people use multiple devices, we interviewed 27 people from academia and industry. From these interviews we distill four primary findings. First, associating a user's activities with a particular device is problematic for multiple device users because many activities span multiple devices. Second, device use varies by user and circumstance; users assign different roles to devices both by choice and by constraint. Third, users in industry want to separate work and personal activities across work and personal devices, but they have difficulty doing so in practice Finally, users employ a variety of techniques for accessing information across devices, but there is room for improvement: participants reported managing information across their devices as the most challenging aspect of using multiple devices. We suggest opportunities to improve the user experience by focusing on the user rather than the applications and devices; making devices aware of their roles; and providing lighter-weight methods for transferring information, including synchronization services that engender more trust from users.

Users increasingly interact with a heterogeneous collection of computing devices. The applications that users employ on those devices, however, still largely provide user experiences that assume the use of a single computer. This failure is due in part to the difficulty of creating user experiences that span multiple devices, particularly the need to manage identifying, connecting to, and communicating with other devices. In this paper we present an infrastructure based on instant messaging that simplifies adding that additional functionality to applications. Our infrastructure elevates device ownership to a first class property, allowing developers to provide functionality that spans personal devices without writing code to manage users' devices or establish connections among them. It also provides simple mechanisms for applications to send information, events, or commands between a user's devices. We demonstrate the effectiveness of our infrastructure by presenting a set of sample applications built with it and a user study demonstrating that developers new to the infrastructure can implement all of the cross-device functionality for three applications in, on average, less than two and a half hours.

We present an empirical study of teams that revealed the amount of extraneous individual work needed to enable collaboration: finding references to other people, finding files to attach to email, managing incoming email attachments, managing the variety of files used in shared activities, and tracking what work is owed to others. Much of this work involves finding recently accessed objects that are needed again in the user's current task focus. These observations led to the design of Recent Shortcuts, a tool to help support coordination by making recently used objects easily accessible. Recent Shortcuts enables quick access to people (including groups of people), received attachments, files, and file folders that the user interacted with recently for re-use in the user's current context. Recent Shortcuts makes it easy to use these objects across applications with no additional user input and minimal changes to the user's applications or work practice. Early user experiences with a working prototype led to an extension that integrates recently accessed objects across multiple devices.

Users are increasingly shifting from interacting with a single, personal computer to interacting across multiple, heterogeneous devices. We present results from a pair of studies investigating specifically how and why users might divide an application's interface across devices in private, semi-private, and public environments. Our results suggest that users are interested in dividing interfaces in all of these environments. While the types of divisions and reasons for dividing varied across users and environments, common themes were that users divided interfaces to improve interaction, to share information, and to balance usability and privacy. Based on our results, we present implications for the design of divisible interfaces.

At work and at play, people need access to the right information, and they frequently need to share that information with others. While current tools such as electronic mail and USB flash drives provide powerful mechanisms for managing and sharing information, they too often require that users anticipate what information they might share (e.g. so they have it on their flash drive) and when they might share it (e.g. so they bring the flash drive with them). These tools thus provide excellent support for planned sharing but inadequate support for serendipitously sharing digital information with others. In this paper we discuss eight design goals that a successful system for serendipitous sharing should meet, and we present SEREFE, a new architecture for SEREndipitous File Exchange that we designed to meet those goals. SEREFE extends an instant messaging architecture to allow users to use any of their devices, including a cell phone, to share information stored on any of their devices with other users or to copy it to another of their devices. We describe the SEREFE user experience, implementation, and initial evaluation results.

Building on Buxton's foreground/background model, we discuss the importance of explicitly considering both foreground interaction and background interaction, as well as transitions between foreground and background, in the design and implementation of sensing techniques for sensor-enhanced mobile devices. Our view is that the foreground concerns deliberate user activity where the user is attending to the device, while the background is the realm of inattention or split attention, using naturally occurring user activity as an input that allows the device to infer or anticipate user needs. The five questions for sensing systems of Bellotti et al. [2002] proposed as a framework for this special issue, primarily address the foreground, but neglect critical issues with background sensing. To support our perspective, we discuss a variety of foreground and background sensing techniques that we have implemented for sensor-enhanced mobile devices, such as powering on the device when the user picks it up, sensing when the user is holding the device to his ear, automatically switching between portrait and landscape display orientations depending on how the user is holding the device, and scrolling the display using tilt. We also contribute system architecture issues, such as using the foreground/background model to handle cross-talk between multiple sensor-based interaction techniques, and theoretical perspectives, such as a classification of recognition errors based on explicitly considering transitions between the foreground and background. Based on our experiences, we propose design issues and lessons learned for foreground/background sensing systems.

Powerful mobile devices with minimal I/O capabilities increase the likelihood that we will want to annex these devices to I/O resources we encounter in the local environment. This opportunistic annexing will require authentication. We present a sensor-based authentication mechanism for mobile devices that relies on physical possession instead of knowledge to setup the initial connection to a public terminal. Our solution provides a simple mechanism for shaking a device to authenticate with the public infrastructure, making few assumptions about the surrounding infrastructure while also maintaining a reasonable level of security.

Defining how 3D models respond to user actions is a crucial step in building an interactive 3D world. Unfortunately, existing tools make it very difficult for interaction designers to assign responses to any part of a 3D model that is not a pre-defined group of polygons. This is particularly problematic for applications that use image-based models or models where most of the detail is in the model's texture map. We present a flexible and easy-to-use technique that overcomes this problem by allowing a designer to specify interaction surfaces, parts of the model he wants to respond to events, by painting them onto the model. We capture the painted areas by projecting them onto a 2D interaction map. An interaction map is similar to a traditional texture, but it specifies interaction surfaces instead of affecting a model's appearance. We allow designers to name interaction surfaces and then assign them responses to events both statically and at run-time. In addition, designers can modify the size and shape of interaction surfaces at run-time and can pass parameters to these surfaces' responses by encoding them in the model's interaction map.

When creating techniques for manipulating objects at a distance in immersive virtual environments, researchers have primarily focused on increasing selection range, placement range, and placement accuracy. This focus has led researchers to create and formally study a series of "arm-extension" techniques, which dynamically scale the user's arm to allow him to manipulate distant objects. Researchers have also developed representation-based techniques, which allow users to manipulate a distant object by manipulating a copy of it in a handheld representation. However, researchers have not yet formally established the relative value of these techniques. In this paper we present a formal study comparing Voodoo Dolls, a best-practice representation-based technique, with HOMER, a best-practice arm-extension technique. We found that the Voodoo Dolls technique, which provides better feedback by allowing users to view a manipulated object both up close and at a distance, allowed users to both position and orient objects more accurately. Our results suggest that researchers should focus on improving feedback for 3D manipulation techniques

We describe sensing techniques motivated by unique aspects of human-computer interaction with handheld devices in mobile settings.Special features of mobile interaction include changing orientation and position, changing venues, the use of computing as auxiliary to ongoing, real-world activities like talking to a colleague, and the general intimacy of use for such devices.We introduce and integrate a set of sensors into a handheld device, and demonstrate several new functionalities engendered by the sensors, such as recording memos when the device is held like a cell phone, switching between portrait and landscape display modes by holding the device in the desired orientation, automatically powering up the device when the user picks it up the device to start using it, and scrolling the display using tilt.We present an informal experiment, initial usability testing results, and user reactions to these techniques.

Users of 3D desktop applications perform tasks that require accessing data storage, moving objects, and navigation. These operations are typically performed using 2D GUI elements or 3D widgets. We wish to focus on interaction with 3D widgets directly in the 3D world, rather than forcing our users to repeatedly switch contexts between 2D and 3D. However, the use of 3D widgets requires a mechanism for storing, accessing, and retrieving these widgets. In this paper we present foolspuces and glances to provide this capability for 3D widgets and other objects in interactive 3D worlds. Toolspaces are storage spaces attached to the user’s virtual body; objects placed in these spaces are always accessible yet out of the user’s view until needed. Users access these toolspaces to store and retrieve objects through a type of lightweight and ephemeral navigation we call glances. CR

The Voodoo Dolls technique is a two-handed interaction technique for manipulating objects at a distance in immersive virtual environments.This technique addresses some limitations of existing techniques: they do not provide a lightweight method of interacting with objects of widely varying sizes, and many limit the objects that can be selected and the manipulations possible after making a selection.With the Voodoo Dolls technique, the user dynamically creates dolls: transient, hand held copies of objects whose effects on the objects they represent are determined by the hand holding them.For simplicity, we assume a right-handed user in the following discussion.When a user holds a doll in his right hand and moves it relative to a doll in his left hand, the object represented by the doll in his right hand moves to the same position and orientation relative to the object represented by the doll in his left hand.The system scales the dolls so that the doll in the left hand is half a meter along its longest dimension and the other dolls maintain the same relative size; this allows the user to work seamlessly at multiple scales.The Voodoo Dolls technique also allows both visible and occluded objects to be selected, and provides a stationary frame of reference for working relative to moving objects.

This paper presents a set of interaction techniques for use in headtracked immersive virtual environments.With these techniques, the user interacts with the 2D projections that 3D objects in the scene make on his image plane.The desktop analog is the use of a mouse to interact with objects in a 3D scene based on their projections on the monitor screen.Participants in an immersive environment can use the techniques we discuss for object selection, object manipulation, and user navigation in virtual environments.

Alice is a rapid prototyping system used to create three dimensional graphics simulations like those seen in virtual reality applications. Alice uses an interpreted language called Python as its scripting language to implement user actions. This interactive development environment allows users to explore many more design options than is possible in a compiled language environment. The alpha version of Alice for Windows 95 is available for free over the intemet, with the beta release scheduled for August.