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ACM Transactions on Computer-Human Interaction 13

Editors:John M. Carroll
Standard No:ISSN 1073-0516
Links:Table of Contents
  1. TOCHI 2006 Volume 13 Issue 1
  2. TOCHI 2006 Volume 13 Issue 2
  3. TOCHI 2006 Volume 13 Issue 3
  4. TOCHI 2006 Volume 13 Issue 4

TOCHI 2006 Volume 13 Issue 1

Blur filtration fails to preserve privacy for home-based video conferencing BIBAFull-Text 1-36
  Carman Neustaedter; Saul Greenberg; Michael Boyle
Always-on video provides rich awareness for distance-separated coworkers. Yet video can threaten privacy, especially when it captures telecommuters working at home. We evaluated video blurring, an image masking method long touted to balance privacy and awareness. Results show that video blurring is unable to balance privacy with awareness for risky situations. Reactions by participants suggest that other popular image masking techniques will be problematic as well. The design implication is that image masking techniques will not suffice for privacy protection in video-based telecommuting situations. Other context-aware privacy-protecting strategies are required, as illustrated in our prototype context-aware home media space.
Queueing Network-Model Human Processor (QN-MHP): A computational architecture for multitask performance in human-machine systems BIBAFull-Text 37-70
  Yili Liu; Robert Feyen; Omer Tsimhoni
Queueing Network-Model Human Processor (QN-MHP) is a computational architecture that integrates two complementary approaches to cognitive modeling: the queueing network approach and the symbolic approach (exemplified by the MHP/GOMS family of models, ACT-R, EPIC, and SOAR). Queueing networks are particularly suited for modeling parallel activities and complex structures. Symbolic models have particular strength in generating a person's actions in specific task situations. By integrating the two approaches, QN-MHP offers an architecture for mathematical modeling and real-time generation of concurrent activities in a truly concurrent manner. QN-MHP expands the three discrete serial stages of MHP, of perceptual, cognitive, and motor processing, into three continuous-transmission subnetworks of servers, each performing distinct psychological functions specified with a GOMS-style language. Multitask performance emerges as the behavior of multiple streams of information flowing through a network, with no need to devise complex, task-specific procedures to either interleave production rules into a serial program (ACT-R), or for an executive process to interactively control task processes (EPIC). Using QN-MHP, a driver performance model was created and interfaced with a driving simulator to perform a vehicle steering, and a map reading task concurrently and in real time. The performance data of the model are similar to human subjects performing the same tasks.
Physically large displays improve performance on spatial tasks BIBAFull-Text 71-99
  Desney S. Tan; Darren Gergle; Peter Scupelli; Randy Pausch
Large wall-sized displays are becoming prevalent. Although researchers have articulated qualitative benefits of group work on large displays, little work has been done to quantify the benefits for individual users. In this article we present four experiments comparing the performance of users working on a large projected wall display to that of users working on a standard desktop monitor. In these experiments, we held the visual angle constant by adjusting the viewing distance to each of the displays. Results from the first two experiments suggest that physically large displays, even when viewed at identical visual angles as smaller ones, help users perform better on mental rotation tasks. We show through the experiments how these results may be attributed, at least in part, to large displays immersing users within the problem space and biasing them into using more efficient cognitive strategies. In the latter two experiments, we extend these results, showing the presence of these effects with more complex tasks, such as 3D navigation and mental map formation and memory. Results further show that the effects of physical display size are independent of other factors that may induce immersion, such as interactivity and mental aids within the virtual environments. We conclude with a general discussion of the findings and possibilities for future work.
Can you see me now? BIBAFull-Text 100-133
  Steve Benford; Andy Crabtree; Martin Flintham; Adam Drozd; Rob Anastasi; Mark Paxton; Nick Tandavanitj; Matt Adams; Ju Row-Farr
We present a study of a mobile mixed reality game called Can You See Me Now? in which online players are chased through a virtual model of a city by 'runners' (professional performers equipped with GPS and WiFi technologies) who have to run through the actual city streets in order to catch the players. We present an ethnographic study of the game as it toured through two different cities and draws upon video recordings of online players, runners, technical support crew, and also on system logs of text communication. Our study reveals the diverse ways in which online players experienced the uncertainties inherent in GPS and WiFi, including being mostly unaware of them, but sometimes seeing them as problems, or treating the as a designed feature of the game, and even occasionally exploiting them within gameplay. In contrast, the runners and technical crew were fully aware of these uncertainties and continually battled against them through an ongoing and distributed process of orchestration. As a result, we encourage designers to deal with such uncertainties as a fundamental characteristic of location-based experiences rather than treating them as exceptions or bugs that might be ironed out in the future. We argue that designers should explicitly consider four potential states of being of a mobile participant: connected and tracked, connected but not tracked, tracked but not connected, and neither connected nor tracked. We then introduce five strategies that might be used to deal with uncertainty in these different states for different kinds of participant: remove it, hide it, manage it, reveal it, and exploit it. Finally, we present proposals for new orchestration interfaces that reveal the 'seams' in the underlying technical infrastructure by visualizing the recent performance of GPS and WiFi and predicting the likely future performance of GPS.

TOCHI 2006 Volume 13 Issue 2

User interfaces for privacy agents BIBAFull-Text 135-178
  Lorrie Faith Cranor; Praveen Guduru; Manjula Arjula
Most people do not often read privacy policies because they tend to be long and difficult to understand. The Platform for Privacy Preferences (P3P) addresses this problem by providing a standard machine-readable format for website privacy policies. P3P user agents can fetch P3P privacy policies automatically, compare them with a user's privacy preferences, and alert and advise the user. Developing user interfaces for P3P user agents is challenging for several reasons: privacy policies are complex, user privacy preferences are often complex and nuanced, users tend to have little experience articulating their privacy preferences, users are generally unfamiliar with much of the terminology used by privacy experts, users often do not understand the privacy-related consequences of their behavior, and users have differing expectations about the type and extent of privacy policy information they would like to see. We developed a P3P user agent called Privacy Bird. Our design was informed by privacy surveys and our previous experience with prototype P3P user agents. We describe our design approach, compare it with the approach used in other P3P use agents, evaluate our design, and make recommendations to designers of other privacy agents.
Zooming versus multiple window interfaces: Cognitive costs of visual comparisons BIBAFull-Text 179-209
  Matthew D. Plumlee; Colin Ware
In order to investigate large information spaces effectively, it is often necessary to employ navigation mechanisms that allow users to view information at different scales. Some tasks require frequent movements and scale changes to search for details and compare them. We present a model that makes predictions about user performance on such comparison tasks with different interface options. A critical factor embodied in this model is the limited capacity of visual working memory, allowing for the cost of visits via fixating eye movements to be compared to the cost of visits that require user interaction with the mouse. This model is tested with an experiment that compares a zooming user interface with a multi-window interface for a multiscale pattern matching task. The results closely matched predictions in task performance times; however error rates were much higher with zooming than with multiple windows. We hypothesized that subjects made more visits in the multi-window condition, and ran a second experiment using an eye tracker to record the pattern of fixations. This revealed that subjects made far more visits back and forth between pattern locations when able to use eye movements than they made with the zooming interface. The results suggest that only a single graphical object was held in visual working memory for comparisons mediated by eye movements, reducing errors by reducing the load on visual working memory. Finally we propose a design heuristic: extra windows are needed when visual comparisons must be made involving patterns of a greater complexity than can be held in visual working memory.
Economic and subjective measures of the perceived value of aesthetics and usability BIBAFull-Text 210-234
  Tamar Ben-Bassat; Joachim Meyer; Noam Tractinsky
The assessment of the relative value of different design features for users is of great interest for software designers. Users' evaluations are generally measured through questionnaires. We suggest that other evaluation methods, including economic measures, may provide different estimates of the relative value of features. In a laboratory experiment we created four versions of a data-entry application by independently manipulating the system's usability and aesthetics. Users' evaluations of the four experimental systems were obtained in a within-subjects design. In addition, five between-subjects experimental conditions were created, based on the evaluation method (questionnaire alone or auction and questionnaire), monetary incentives (present or absent), and experience in using the system (present or absent). In questionnaire-based responses, the systems' usability affected evaluations of usability as well as aesthetics. Similarly, the systems' aesthetics affected evaluations of both aesthetics and usability. Questionnaire-based evaluations of usability and aesthetics were not affected by experience with the system or by monetary performance incentives. Auction bids were only influenced by the system's usability: bids corresponded to the objective performance levels that could be attained with the different systems. The results suggest that by using economic methods, researchers and practitioners can obtain system evaluations that are strongly related to performance criteria and that may be more valid when the evaluation context favors task-oriented performance.
Investigating interaction in CAVE virtual environments BIBAFull-Text 235-267
  Alistair Sutcliffe; Brian Gault; Terence Fernando; Kevin Tan
An experimental comparison of interaction in the real world and a CAVE virtual environment was carried out, varying interaction with and without virtual hands and comparing two manipulation tasks. The double-handed task was possible in the real world but nearly impossible in the VE, leading to changed behavior. The single-handed task showed more errors in the VE but few behavioral differences. Users encountered more errors in the CAVE condition without the virtual hand than with it, and few errors in the real world. Visual feedback caused many usability problems in both tasks. The implications for VE usability and virtual prototyping are discussed.
Spatial graph grammars for graphical user interfaces BIBAFull-Text 268-307
  Jun Kong; Kang Zhang; Xiaoqin Zeng
In a graphical user interface, physical layout and abstract structure are two important aspects of a graph. This article proposes a new graph grammar formalism which integrates both the spatial and structural specification mechanisms in a single framework. This formalism is equipped with a parser that performs in polynomial time with an improved parsing complexity over its nonspatial predecessor, that is, the Reserved Graph Grammar. With the extended expressive power, the formalism is suitable for many user interface applications. The article presents its application in adaptive Web design and presentation.

TOCHI 2006 Volume 13 Issue 3

Introduction to the special issue on information systems for an aging society BIBFull-Text 309-312
  Starr Roxanne Hiltz; Sara J. Czaja
Shared family calendars: Promoting symmetry and accessibility BIBAFull-Text 313-346
  Catherine Plaisant; Aaron Clamage; Hilary Browne Hutchinson; Benjamin B. Bederson; Allison Druin
We describe the design and use of a system facilitating the sharing of calendar information between remotely located, multi-generational family members. Most previous work in this area involves software enabling younger family members to monitor their parents. We have found, however, that older adults are equally if not more interested in the activities of younger family members. The major obstacle preventing them from participating in information sharing is the technology itself. Therefore, we developed a multi-layered interface approach that offers simple interaction to older users. In our system, users can choose to enter information into a computerized calendar or write it by hand on digital paper calendars. All of the information is automatically shared among everyone in the distributed family. By making the interface more accessible to older users, we promote symmetrical sharing of information among both older and younger family members. We present our participatory design process, describe the user interface, and report on an exploratory field study in three households of an extended family.
Designing a portal for older users: A case study of an industrial/academic collaboration BIBAFull-Text 347-375
  Alan F. Newell; Anna Dickinson; Mick J. Smith; Peter Gregor
A multidisciplinary team from industry, government, and academia developed prototype email, Web search, and navigation systems for users over 60 years old who were inexperienced in using computers and had never used the Internet. The academics encountered problems in persuading other team members of the specific challenges of designing for and working with older people. A number of ways of overcoming such challenges were implemented, and the final "radically simple" systems evaluated by a team of older people. The collaboration highlighted the conflicting pressures of the commercial world and the time and patience needed to design for older users.
Leveraging data complexity: Pupillary behavior of older adults with visual impairment during HCI BIBAFull-Text 376-402
  Kevin P. Moloney; Julie A. Jacko; Brani Vidakovic; Francois Sainfort; V. Kathlene Leonard; Bin Shi
The current ubiquity of information technology has increased variability among users, creating a corresponding need to properly capture and understand these individual differences. This study introduces a novel application of multifractal statistical methods to distinguish users via patterns of variability within high frequency pupillary response behavior (PRB) data collected during computer-based interaction. PRB was measured from older adults, including two groups diagnosed with age-related macular degeneration (AMD) maintaining a range of visual acuities (n = 14), and one visually healthy control group (i.e., disease-free, 20/20-20/32 acuity) (n = 14). Three measures of the multifractal spectrum, the distribution of regularity indices extracted from time series data, distinguished the user groups, including: 1) Spectral Mode; 2) Broadness; and 3) Left Slope. The results demonstrate a clear relationship between the values of these measures and the level of visual capabilities. These analytical techniques leverage the inherent complexity and richness of this high frequency physiological response data, which can be used to meaningfully differentiate individuals whose sensory and cognitive capabilities may be affected by aging and visual impairment. Multifractality analysis provides an objective, quantifiable means of uncovering and examining the underlying signatures in physiological behavior that may account for individual differences in interaction needs and behaviors.
Trends, similarities, and differences in the usage of teen and senior public online newsgroups BIBAFull-Text 403-422
  Panayiotis Zaphiris; Rifaht Sarwar
This article presents an analysis of the human to human interactions in two public online newsgroups, one targeting the young generation and the other the elderly. The main goal of this study was to establish a better understanding of similarities and differences in the ways of interacting among the participants of these two newsgroups. A series of analytical/statistical techniques, like Social Network Analysis (SNA), were used in order to get a better understanding of the online communities that have emerged around the participants of these two newsgroups. The SNA analysis showed that the teens newsgroup is more highly connected, has more messages sent and received and has a higher reciprocity. On the other hand, the senior newsgroup has more central dominant people who tend to make the rest of the network dependent on them for communication.

TOCHI 2006 Volume 13 Issue 4

Chatting with teenagers: Considering the place of chat technologies in teen life BIBAFull-Text 423-447
  Rebecca E. Grinter; Leysia Palen; Margery Eldridge
In the last few years, teenagers have been on the forefront of adopting short message service (SMS), a mobile phone-based text messaging system, and instant messaging (IM), a computer-based text chat system. However, while teenage adoption of SMS had led to a series of studies examining the reasons for its popularity, IM use in the teenage population remains understudied. This omission becomes significant given the increasing interest in domestic computing among human-computer interaction (HCI) and computer-supported cooperative work (CSCW) researchers. Further, because of the dearth of empirical work on teenage use of IM, we find that IM and SMS are sometimes incorrectly assumed to share the same features of use. To address these concerns, we revisit our own studies of SMS and IM use and reexamine them in tandem with other published studies on teenage chat. We consider similarities and differences in styles of SMS and IM use and how chat technologies enable the pursuit of teenage independence. We examine how differences are born out of technological differences and financial cost structures. We discuss how SMS and IM are used in concert to provide increased awareness and to coordinate inter-household communications, and how privacy is regulated within the individual household as a means of maintaining these communications.
Navigating on handheld displays: Dynamic versus static peephole navigation BIBAFull-Text 448-457
  Sumit Mehra; Peter Werkhoven; Marcel Worring
Handheld displays leave little space for the visualization and navigation of spatial layouts representing rich information spaces. The most common navigation method for handheld displays is static peephole navigation: The peephole is static and we move the spatial layout behind it (scrolling). A more natural method is dynamic peephole navigation: here, the spatial layout is static and we move the peephole across it. In the experiment reported here, we compared dynamic and static peephole navigation in otherwise similar conditions. Subjects viewed a spatial layout containing two lines on a static display screen. Only a part of the screen -- the peephole -- was visible. Subjects had to discriminate line length by either moving a dynamic peephole across a static layout of the lines or by moving a dynamic layout behind a static peephole. In both conditions, they used mouse-cursor control to move either the peephole or the lines.
   Results show significant differences in discrimination performance between conditions when lines are larger than the size of the peephole. Discrimination thresholds for static peephole navigation were 50-75% higher than for dynamic peephole navigation. Furthermore, static peephole navigation took 24% more time than dynamic peephole navigation.
Analyzing the input stream for character-level errors in unconstrained text entry evaluations BIBAFull-Text 458-489
  Jacob O. Wobbrock; Brad A. Myers
Recent improvements in text entry error rate measurement have enabled the running of text entry experiments in which subjects are free to correct errors (or not) as they transcribe a presented string. In these "unconstrained" experiments, it is no longer necessary to force subjects to unnaturally maintain synchronicity with presented text for the sake of performing overall error rate calculations. However, the calculation of character-level error rates, which can be trivial in artificially constrained evaluations, is far more complicated in unconstrained text entry evaluations because it is difficult to infer a subject's intention at every character. For this reason, prior character-level error analyses for unconstrained experiments have only compared presented and transcribed strings, not input streams. But input streams are rich sources of character-level error information, since they contain all of the text entered (and erased) by a subject. The current work presents an algorithm for the automated analysis of character-level errors in input streams for unconstrained text entry evaluations. It also presents new character-level metrics that can aid method designers in refining text entry methods. To exercise these metrics, we perform two analyses on data from an actual text entry experiment. One analysis, available from the prior work, uses only presented and transcribed strings. The other analysis uses input streams, as described in the current work. The results confirm that input stream error analysis yields richer information for the same empirical data. To facilitate the use of these new analyses, we offer pseudocode and downloadable software for performing unconstrained text entry experiments and analyzing data.
The reification of metaphor as a design tool BIBAFull-Text 490-530
  Alan F. Blackwell
Despite causing many debates in human-computer interaction (HCI), the term "metaphor" remains a central element of design practice. This article investigates the history of ideas behind user-interface (UI) metaphor, not only technical developments, but also less familiar perspectives from education, philosophy, and the sociology of science. The historical analysis is complemented by a study of attitudes toward metaphor among HCI researchers 30 years later. Working from these two streams of evidence, we find new insights into the way that theories in HCI are related to interface design, and offer recommendations regarding approaches to future UI design research.
Transparent adaptation of single-user applications for multi-user real-time collaboration BIBAFull-Text 531-582
  Chengzheng Sun; Steven Xia; David Sun; David Chen; Haifeng Shen; Wentong Cai
Single-user interactive computer applications are pervasive in our daily lives and work. Leveraging single-user applications for supporting multi-user collaboration has the potential to significantly increase the availability and improve the usability of collaborative applications. In this article, we report an innovative Transparent Adaptation (TA) approach and associated supporting techniques that can be used to convert existing and new single-user applications into collaborative ones, without changing the source code of the original application. The cornerstone of the TA approach is the operational transformation (OT) technique and the method of adapting the single-user application programming interface to the data and operation models of OT. This approach and supporting techniques were developed and tested in the process of transparently converting two commercial off-the-shelf single-user applications (Microsoft Word and PowerPoint) into real-time collaborative applications, called CoWord and CoPowerPoint, respectively. CoWord and CoPowerPoint not only retain the functionalities and "look-and-feel" of their single-user counterparts, but also provide advanced multi-user collaboration capabilities for supporting multiple interaction paradigms, ranging from concurrent and free interaction to sequential and synchronized interaction, and for supporting detailed workspace awareness, including multi-user telepointers and radar views. The TA approach and generic collaboration engine software component developed from this work are potentially applicable and reusable in adapting a wide range of single-user applications.