| Consistency maintenance in real-time collaborative graphics editing systems | | BIBAK | Full-Text | 1-41 | |
| Chengzheng Sun; David Chen | |||
| Real-time collaborative graphics editing systems allow a group of users to
view and edit the same graphics document at the same time from geographically
dispersed sites connected by communication networks. Consistency maintenance in
the face of concurrent accesses to shared objects is one of the core issues in
the design of these types of systems. In this article, we propose an
object-level multiversioning approach to consistency maintenance in real-time
collaborative graphic editors. This approach is novel in achieving intention
preservation and convergence, in preserving the work concurrently produced by
multiple users in the face of conflict, and in minimizing the number of object
versions for conflict resolution. Major technical contributions of this work
include a formal specification of a unique combined effect for an arbitrary
group of conflict and compatible operations, a distributed algorithm for
incremental creation of multiple object versions, a consistent object
identification scheme for multiple object versions, and a convergent layering
scheme for overlapping objects. All algorithms and schemes presented in this
article have been implemented in an Internet-based GRACE (graphics
collaborative editing) system. Keywords: Collaborative graphics editors, GRACE, computer-supported cooperative work,
consistence maintenance, convergence, groupware, intention preservation,
multiversioning | |||
| The importance of translucence in mobile computing systems | | BIBAK | Full-Text | 42-67 | |
| Maria R. Ebling; Bonnie E. John; M. Satyanarayanan | |||
| Mobile computing has been an active area of research for the past decade,
but its importance will increase substantially in the decade to come. One
problem faced by designers of mobile systems is that of maintaining the
illusion of connectivity even when network performance is poor or non-existent.
The Coda file system uses its cache to maintain this illusion. Extensive
experience with the system suggests that, although users find the functionality
provided by the system extremely valuable, new users face an arduous learning
curve and even experienced users are sometimes confused by the system's
behavior. The fundamental problem is that the lack of a strong network
connection causes the system to violate a key property of caching:
transparency. To overcome this problem, we have built an interface, called the
CodaConsole, that makes caching translucent to users through controlled
exposure of cache management internals. The interface exposes critical aspects
of caching to support the mobile user while hiding noncritical details to
preserve usability. This article presents the design, implementation, and
usability evaluation of this interface. The CodaConsole successfully makes
caching translucent in the presence of disconnected or weakly connected
operation. The most surprising result was that novice Coda users performed
almost as well as experienced Coda users. Keywords: operation | |||
| Introduction to the new usability | | BIBAK | Full-Text | 69-73 | |
| Peter Thomas; Robert D. Macredie | |||
| This paper introduces the motivation for and concept of the "new usability"
and positions it against existing approaches to usability. It is argued that
the contexts of emerging products and systems mean that traditional approaches
to usability engineering and evaluation are likely to prove inappropriate to
the needs of "digital consumers." The paper briefly reviews the contributions
to this special issue in terms of their relation to the idea of the "new
usability" and their individual approaches to dealing with contemporary
usability issues. This helps provide a background to the "new usability"
research agenda, and the paper ends by posing what are argued to be the central
challenges facing the area and those which lie at the heart of the proposed
research agenda. Keywords: Internet appliances, design, new usability, ubiquitous computing, usability
engineering | |||
| The usability of everyday technology: emerging and fading opportunities | | BIBAK | Full-Text | 74-105 | |
| Marianne Graves Petersen; Kim Halskov Madsen; Arne Kjaer | |||
| Current work in the field of usability tends to focus on snapshots of use as
the basis for evaluating designs. However, giving due consideration to the fact
that everyday use of technology involves a process of evolution, we set out to
investigate how the design of the technology may be used to support this. Based
on a long-term empirical study of television use in the homes of two families,
we illustrate how use continuously develops in a complex interplay between the
users' expectations -- as they are formed and triggered by the design -- and
the needs and context of use per se. We analyze the empirical data from the
perspective of activity theory. This framework serves to highlight how use
develops, and it supports our analysis and discussion about how design, the
users' backgrounds, previous experience, and needs, and the specific context of
use supports or hinders the development of use. Moreover, we discuss how the
characteristics of the home settings, in which the televisions studied were
situated, represent a challenge to usability work. The concluding discussion
leads to a set of hypotheses relevant to designers and researchers who wish to
tackle some of the aspects of usability of particular importance to development
in the use of home technology. Keywords: TV set, activity theory, case study, design, development in use, domestic
technology, usability | |||
| From use to presence: on the expressions and aesthetics of everyday computational things | | BIBAK | Full-Text | 106-124 | |
| Lars Hallnas; Johan Redstrom | |||
| The coming ubiquity of computational things urges us to consider what it
means for something to be present in someone's life, in contrast to being just
used for something. "Use" and "presence" represent two perspectives on what a
thing is. While "use" refers to a general description of a thing in terms of
what it is used for, "presence" refers to existential definitions of a thing
based on how we invite and accept it as a part of our lifeworld. Searching for
a basis on which these existential definitions are formed, we argue that the
expressions of things are central for accepting them as present in our lives.
We introduce the notion of an expressional, referring to a thing designed to be
the bearer of certain expressions, just as an appliance is designed to be the
bearer of a certain functionality. Aesthetics, as a logic of expressions, can
provide a proper foundation for design for presence. We discuss the
expressiveness of computational things as depending both on time structures and
space structures. An aesthetical leitmotif for the design of computational
things -- a leitmotif that may be used to guide a normative design philosophy,
or a design style -- is described. Finally, we describe a practical example of
what designing a mobile phone as an "expressional" might be like. Keywords: aesthetics, design, information appliances, phenomenology, ubiquitous
computing | |||
| Beyond the handset: designing for wireless communications usability | | BIBAK | Full-Text | 125-151 | |
| Leysia Palen; Marilyn Salzman | |||
| Service-based wireless devices like wireless telephones require users to
interact with aspects of the technology beyond the hardware and software of the
handset. By entering into contractual relationships with service-providers, and
by using network-based services, users interact with a larger system -- one
that has social and technological components. The operation of the wireless
telephone requires the assimilation of heterogeneous sources of information
from the device manufacturer, sales people, customer service representatives,
marketing people, and members of the popular media, among others, which can
easily confound users' understanding of this new class of technology.
Opportunities for usability problems therefore scale beyond the handset, as do
opportunities for better design. We report the results of a study of 19 novice
wireless phone users who were closely tracked for the first 6 weeks after
service acquisition. Taking a technology-as-system analytical approach, we
describe the wireless telephony system as four socio-technical components:
hardware, software, "netware," and "bizware." This particular organization of
the system is intended for the practical application of designing for
usability. Keywords: cell, field study, mobile, qualitative study, social construction of
technology, socio-technical systems, usability, wireless telephones | |||
| The design collaboratorium: a place for usability design | | BIBAK | Full-Text | 152-169 | |
| Susanne Bødker; Jacob Buur | |||
| The "design collaboratorium" is a new usability practice that has been
developed in an action research project between three industrial usability labs
and a university. The design collaboratorium has been developed as a reaction
to the failing capabilities of classical usability methods to cope with
ubiquitous technologies. It has borrowed elements from participatory design and
developed them further to become useful in large-scale industrial development
organizations. The design collaboratorium will be presented through examples
from a joint project: a vision project concerning wastewater treatment
technology. In light of the case, we will discuss the philosophy underlying the
design collaboratorium in further detail: the collaboration between active
participants, the role of design artifacts, and the room as a meeting ground.
Finally we lay out the working method and propose directions for future
usability competencies. Keywords: cooperative design, ubiquitous and mobile technology, usability practice,
user interface methodology | |||
| Multimodal human discourse: gesture and speech | | BIBAK | Full-Text | 171-193 | |
| Francis Quek; David McNeill; Robert Bryll; Susan Duncan; Xin-Feng Ma; Cemil Kirbas; Karl E. McCullough; Rashid Ansari | |||
| Gesture and speech combine to form a rich basis for human conversational
interaction. To exploit these modalities in HCI, we need to understand the
interplay between them and the way in which they support communication. We
propose a framework for the gesture research done to date, and present our work
on the cross-modal cues for discourse segmentation in free-form gesticulation
accompanying speech in natural conversation as a new paradigm for such
multimodal interaction. The basis for this integration is the psycholinguistic
concept of the coequal generation of gesture and speech from the same semantic
intent. We present a detailed case study of a gesture and speech elicitation
experiment in which a subject describes her living space to an interlocutor. We
perform two independent sets of analyses on the video and audio data: video and
audio analysis to extract segmentation cues, and expert transcription of the
speech and gesture data by microanalyzing the videotape using a frame-accurate
videoplayer to correlate the speech with the gestural entities. We compare the
results of both analyses to identify the cues accessible in the gestural and
audio data that correlate well with the expert psycholinguistic analysis. We
show that "handedness" and the kind of symmetry in two-handed gestures provide
effective supersegmental discourse cues. Keywords: Multimodal interaction, conversational interaction, discourse, gesture,
gesture analysis, human interaction models, speech | |||
| Cooperative visual manipulation of music notation | | BIBAK | Full-Text | 194-237 | |
| P. Bellini; P. Nesi; M. B. Spinu | |||
| As computer technologies and their potential emerging applications spread
out, new needs have been detected for computer-based applications of music;
cooperative music notation editing both in orchestras and music schools is one
of them. This article is the only public document describing the details of
cooperative work on music notation of MOODS (Music Object Oriented Distributed
System). MOODS is a synchronous real-time cooperative editor for music scores.
Its architecture includes mechanisms for troubleshooting conflicts in
real-time, managing histories of commands and versioning, and for performing
selective undo. The system also includes specific solutions in order to control
the editing on the account of editing permission profiles. The most important
aspects of MOODS associated with cooperative work on music notation scores are
reported herein. The article highlights the general problems of cooperative
systems and provides rationales for the solutions, which were found to build
MOODS. The MOODS system has been implemented and validated thanks to the
endeavor of several musicians in orchestras, music schools, and project
partners. A prototype has been demonstrated in public at the Scala Theatre in
Milan, Italy. Keywords: Collaboration of music notation editing, additional command list,
collaborative systems, computer-supported cooperative work, consistency
control, cooperative music, distributed music, electronic lectern, neutral
version, selective undo, user interface management systems | |||
| Rivalry and interference with a head-mounted display | | BIBAK | Full-Text | 238-251 | |
| Robert S. Laramee; Colin Ware | |||
| Perceptual factors that affect monocular, transparent (a.k.a "see-thru")
head-mounted displays include binocular rivalry, visual interference, and depth
of focus. We report the results of an experiment designed to evaluate the
effects of these factors on user performance in a table look-up task. Two
backgrounds were used. A dynamic moving background was provided by a large
screen TV and an untidy bookshelf was used to provide a complex static
background. With the TV background large effects were found attributable to
both rivalry and visual interference. These two effects were roughly additive.
Smaller effects were found with the bookshelf. In conclusion we suggest that
monocular transparent HMDs may be unsuitable for use in visually dynamic
environments. However when backgrounds are relatively static, having a
transparent display may be preferable to having an opaque display. Keywords: Wearable computing, augmented reality, binocular rivalry, head-mounted
display, heads-up display, mobile computing devices, see-thru Display, visual
interference | |||
| Appendices A--D: A scalable method for deductive generalization in the spreadsheet paradigm | | BIB | Full-Text | 1-5 | |
| Margaret Burnett; Sherry Yang; Jay Summet | |||
| A scalable method for deductive generalization in the spreadsheet paradigm | | BIBAK | Full-Text | 253-284 | |
| Margaret Burnett; Sherry Yang; Jay Summet | |||
| In this paper, we present an efficient method for automatically generalizing
programs written in spreadsheet languages. The strategy is to do generalization
through incremental analysis of logical relationships among concrete program
entities from the perspective of a particular computational goal. The method
uses deductive dataflow analysis with algebraic back-substitution rather than
inference with heuristics, and there is no need for generalization-related
dialog with the user. We present the algorithms and their time complexities and
show that, because the algorithms perform their analyses incrementally, on only
the on-screen program elements rather than on the entire program, the method is
scalable. Performance data is presented to help demonstrate the scalability. Keywords: Forms/3, Human-computer interaction, concrete programming, generalization,
graphical programming, spreadsheet languages | |||
| Symmetric and asymmetric action integration during cooperative object manipulation in virtual environments | | BIBAK | Full-Text | 285-308 | |
| Roy A. Ruddle; Justin C. D. Savage; Dylan M. Jones | |||
| Cooperation between multiple users in a virtual environment (VE) can take
place at one of three levels. These are defined as where users can perceive
each other (Level 1), individually change the scene (Level 2), or
simultaneously act on and manipulate the same object (Level 3). Despite
representing the highest level of cooperation, multiuser object manipulation
has rarely been studied. This paper describes a behavioral experiment in which
the piano movers' problem (maneuvering a large object through a restricted
space) was used to investigate object manipulation by pairs of participants in
a VE. Participants' interactions with the object were integrated together
either symmetrically or asymmetrically. The former only allowed the common
component of participants' actions to take place, but the latter used the mean.
Symmetric action integration was superior for sections of the task when both
participants had to perform similar actions, but if participants had to move in
different ways (e.g., one maneuvering him/herself through a narrow opening
while the other traveled down a wide corridor) then asymmetric integration was
superior. With both forms of integration, the extent to which participants
coordinated their actions was poor and this led to a substantial cooperation
overhead (the reduction in performance caused by having to cooperate with
another person). Keywords: Virtual environments, object manipulation, piano movers' problem, rules of
interaction | |||
| Undo as concurrent inverse in group editors | | BIBAK | Full-Text | 309-361 | |
| Chengzheng Sun | |||
| As an important mechanism for error recovery and exploration of alternatives
in interactive and collaborative applications, an undo facility should have the
capability of undoing any operation at any time. However, supporting undo in
collaborative applications is technically challenging and none of the existing
group undo solutions is able to offer such a capability. In this article, we
contribute an undo solution with such a capability for group text editors. The
basic idea is to interpret an undo command as a concurrent inverse operation by
means of operational transformation. To cope with the high complexity of group
undo, a generic undo framework has been adopted to separate undo policy from
the undo mechanism and to separate transformation control algorithms from
transformation functions. The proposed undo solution consists of a generic
transformation control algorithm that is capable of generating, transforming,
and representing valid inverse operations in any context, and a set of
transformation functions that are capable of preserving undo-related
transformation conditions and properties. Formal proofs are provided to show
the correctness of the undo transformation control algorithm in achieving the
required undo effect, undo property, and consistency properties. Solutions to
the known undo puzzles are provided to show soundness of the transformation
functions. A Web-based group text editor REDUCE (REal-time Distributed
Unconstrained Cooperative Editing) has been implemented to demonstrate the
feasibility and usability of the proposed undo and other technical solutions.
The proposed undo solution is generally applicable to collaborative
applications that support concurrent insertion and deletion on shared documents
consisting of one or multiple dimensions of linearly ordered data objects with
positional references. Keywords: Group undo, REDUCE, collaborative applications, computer-supported
cooperative work, concurrency control, consistence maintenance, distributed
systems, operational transformation | |||
| Navigation patterns and usability of zoomable user interfaces with and without an overview | | BIBAK | Full-Text | 362-389 | |
| Kasper Hornbaek; Benjamin B. Bederson; Catherine Plaisant | |||
| The literature on information visualization establishes the usability of
interfaces with an overview of the information space, but for zoomable user
interfaces, results are mixed. We compare zoomable user interfaces with and
without an overview to understand the navigation patterns and usability of
these interfaces. Thirty-two subjects solved navigation and browsing tasks on
two maps. We found no difference between interfaces in subjects' ability to
solve tasks correctly. Eighty percent of the subjects preferred the interface
with an overview, stating that it supported navigation and helped keep track of
their position on the map. However, subjects were faster with the interface
without an overview when using one of the two maps. We conjecture that this
difference was due to the organization of that map in multiple levels, which
rendered the overview unnecessary by providing richer navigation cues through
semantic zooming. The combination of that map and the interface without an
overview also improved subjects' recall of objects on the map. Subjects who
switched between the overview and the detail windows used more time, suggesting
that integration of overview and detail windows adds complexity and requires
additional mental and motor effort. Keywords: Information visualization, levels of detail, maps, navigation,
overview+detail interfaces, overviews, usability, zoomable user interfaces
(ZUIs) | |||