Using Multi-touch Interaction
Techniques to Support Collaborative
Information Retrieval
Ivan Sams (MSc)
Supervisors: Prof. Janet Wesson & Dr Dieter Vogts
Submitted in fulfilment of the requirements for the degree of
Magister Scientiae in Computing Sciences at the
Nelson Mandela Metropolitan University
Acknowledgements
The author wishes to thank the following people and organisations for their support in the completion of this project.
My supervisor, Prof. Janet Wesson, for her invaluable advice, guidance and motivation throughout the project.
My co-supervisor, Dr Dieter Vogts, for his interest, willingness to help and share his technical knowledge.
My colleagues in the NMMU Computing Sciences department, particularly Desma van der Walt, Carol van Onselen, Erna Milbourn, Hayley Irvine, Jean Rademakers and Charl van der Merwe, who all willingly went out of their way in providing support of a technical or administrative nature. Dr Lester Cowley for his assistance with setting up and designing the hardware and maintaining an interest in the project and my success. Prof. Charmain Cilliers, who assisted me with my ethics application. Prof. Andre Calitz for helping me with accommodation. Clayton Burger for checking this dissertation for technical and stylistic accuracy.
Danie Venter from the NMMU Unit for Statistical Consultation for his assistance with the preparation and analysis of the statistical results of the evaluation.
Hans van de Groenendaal from Engineer IT magazine, for his interest in the project and the article he published about it.
Phil Haussler from NMMU Media Services for his expert editing and production of the Co-IMBRA video tutorial.
The Telkom/NMMU Centre of Excellence (CoE) for providing the equipment required as well as their financial assistance.
NMMU Research Capacity Development (RCD) for their financial assistance. The National Research Foundation (NRF) for their financial assistance. The thirty individuals who enthusiastically took part in the user study.
My family and friends for their unfailing personal support during my studies, particularly Kristi Maciejewski, who inspired me during difficult times in this study and Jean-Pierre Joubert, whose friendship has supported me throughout my six years of study at NMMU.
Summary
Collaborative Information Retrieval (CIR) is a branch of Computer Supported Cooperative Work (CSCW). CIR is the process by which people search for and retrieve information, working together and using documents as data sources. Currently, computer support for CIR is limited to single user systems. Collaboration takes place either with users working at different times or in different locations.
Multi-touch interaction has recently seen a rise in prominence owing to a reduction in the cost of the technology and increased frequency of use. Multi-touch surface computing allows multiple users to interact at once around a shared display. The aim of this research was to investigate how multi-touch interaction techniques could be used to support CIR effectively in a co-located environment. An application architecture for CIR systems that incorporates multi-touch interaction techniques was proposed. A prototype, called Co-IMBRA, was developed based on this architecture that used multi-touch interaction techniques to support CIR. This prototype allows multiple users to retrieve information, using the Internet as a shared information space. Documents are represented as visual objects that can be manipulated on the multi-touch surface, as well as rated, annotated and added to folders.
A user study was undertaken to evaluate Co-IMBRA and determine whether the multi-touch interaction techniques effectively supported CIR. Fifteen teams of two users each participated in the user study. High task completion rates and low task times showed that the system was effective and efficient. High levels of user satisfaction were reported in the post-test questionnaires. Participants rated the system as highly useful and several commented that it promoted collaboration and that they enjoyed the test.
The successful implementation of Co-IMBRA provides evidence that multi-touch interaction techniques can effectively support CIR. The results of the user evaluation also enabled recommendations for future research to be made.
Keywords: Computer Supported Cooperative Work (CSCW), Collaborative Information Retrieval (CIR), multi-touch surface computing, Gesture Based Interaction (GBI), co-located multi-user systems.
Tables of Contents
Acknowledgements ... ii
Summary ... iii
Tables of Contents ... iv
List of Figures ... xi
List of Tables ... xiii
Dedication ... xiv
Glossary and Abbreviations ... xv
Introduction ... 1 Chapter 1: 1.1 Background ... 1 1.2 Problem Statement ... 2 1.3 Thesis Statement ... 2 1.4 Research Objectives ... 2 1.5 Research Questions ... 3
1.6 Scope and Constraints ... 3
1.7 Research Methodology ... 3
1.7.1 Literature Study ... 4
1.7.2 Analysis and Design ... 4
1.7.3 Prototype ... 4
1.7.4 Experiment ... 4
1.8 Dissertation Outline ... 5
1.8.1 Chapter 1: Introduction ... 5
1.8.2 Chapter 2: Collaborative Information Retrieval ... 5
1.8.4 Chapter 4: Design and Implementation ... 6
1.8.5 Chapter 5: Evaluation ... 6
1.8.6 Chapter 6: Conclusion ... 6
1.9 Conclusions ... 6
Collaborative Information Retrieval ... 8
Chapter 2: 2.1 Introduction ... 8
2.2 CIR Research Questions ... 8
2.3 Definitions and Overview ... 8
2.3.1 Computer Supported Cooperative Work ... 9
2.3.2 Groupware ... 9
2.3.3 Collaborative Information Retrieval ... 9
2.3.4 Collaborative Information Sharing ... 10
2.3.4.1 Strategic information sharing ... 11
2.3.4.2 Paradigmatic information sharing ... 11
2.3.4.3 Directive information sharing ... 11
2.3.4.4 Social information sharing... 11
2.4 Applications of CIR ... 11
2.5 Tasks Required for CIR ... 12
2.5.1 Information seeking or searching ... 14
2.5.2 Information Retrieval ... 14
2.6 Components and Requirements of CIR ... 15
2.6.1 Motivation for CIR ... 15
2.6.2 Benefits of using CIR ... 15
2.6.3 Problems and shortcomings of CIR ... 16
2.6.6 Non-functional requirements of CIR ... 21
2.7 Tools to support CIR ... 22
2.7.1 Ariadne ... 22
2.7.2 SearchTogether ... 23
2.7.3 Coagmento ... 24
2.7.4 Cerciamo ... 25
2.7.5 Annotate! ... 26
2.8 Comparison and Evaluation of CIR systems ... 27
2.9 Conclusions ... 31 Multi-touch Interaction ... 33 Chapter 3: 3.1 Introduction ... 33 3.2 Multi-touch Technology ... 33 3.2.1 Background ... 33
3.2.2 Advantages and Limitations ... 33
3.2.3 Multi-touch Sensing ... 34
3.3 Existing Multi-Touch Interaction Techniques ... 36
3.3.1 Pointing ... 40
3.3.2 Selection ... 41
3.3.3 Manipulation ... 41
3.3.4 Changing View ... 42
3.3.5 Commands Using Gesture Based Interaction ... 43
3.4 Limitations of Multi-touch Interaction ... 44
3.4.1 Feedback ... 44
3.4.2 Precision ... 45
3.4.3 Fatigue ... 46
3.6 Mapping of CIR Tasks to Multi-touch Interaction Techniques ... 47
3.7 Conclusions ... 49
Design and Implementation ... 50
Chapter 4: 4.1 Introduction ... 50 4.2 Development Methodology ... 50 4.3 Design ... 50 4.3.1 Architecture ... 51 4.3.2 Data ... 56 4.3.3 User Interface ... 59 4.3.3.1 Workspace ... 59 4.3.3.2 Information Controls ... 60 4.3.3.3 Widgets ... 63 4.3.4 User Identification ... 67 4.4 Implementation ... 68 4.4.1 Application Domain ... 68 4.4.2 Implementation tools ... 69 4.4.2.1 Hardware ... 69 4.4.2.2 Hardware SDK ... 71 4.4.2.3 Graphics ... 71 4.4.2.4 Programming Language ... 71
4.4.2.5 Integrated Development Environment (IDE) Software ... 72
4.4.2.6 GestureToolkit ... 72
4.4.2.7 Awesomium ... 72
4.4.3 Functionality ... 73
4.4.3.3 Present or visualise the search results or shared information ... 75
4.4.3.4 Collaboratively navigate through and retrieve search results ... 75
4.4.3.5 Open documents to use as information sources... 75
4.4.3.6 Manipulate the search results or shared information ... 75
4.4.3.7 Update or add value to shared information ... 76
4.4.3.8 Update users on other users’ actions ... 76
4.4.3.9 Enable communication between group members ... 77
4.4.3.10 Enable division of workload between group members ... 77
4.4.3.11 Store logs of user actions, such as communication and searches ... 77
4.4.3.12 Enable users to refind and reuse information. ... 78
4.5 Discussion ... 78 4.6 Conclusion ... 79 Evaluation ... 81 Chapter 5: 5.1Introduction ... 81 5.2Evaluation Goals ... 81 5.3 Evaluation Methods ... 82
5.3.1 Evaluating Collaborative Information Retrieval Systems ... 82
5.3.2 Evaluating Multi-touch Systems ... 84
5.3.3 Selection of evaluation methods ... 89
5.4 User Study ... 90
5.4.1 Experimental Design ... 90
5.4.2 Data Collection Methods ... 90
5.4.3 Metrics ... 91
5.4.4 Instruments and Location ... 92
5.4.5 Participants ... 92
5.4.7 Questionnaires ... 93
5.4.8 Test Procedure ... 93
5.4.9 Statistics ... 94
5.5 Results and Analysis ... 94
5.5.1 Demographics ... 95 5.5.1.1 Participant demographics ... 95 5.5.1.2 Team Demographics ... 97 5.5.2 Performance Results ... 98 5.5.3 Satisfaction Results ... 102 5.5.4 Collaboration Results ... 109
5.5.5 Qualitative Feedback and Observations ... 110
5.6 Design Implications ... 113 5.7 Conclusions ... 115 Conclusion ... 118 Chapter 6: 6.1 Introduction ... 118 6.2 Achievements ... 118 6.3 Research Contribution ... 121 6.3.1 Theoretical ... 122 6.3.2 Practical ... 123 6.4 Problems Encountered ... 123 6.5 Limitations ... 124 6.6 Recommendations ... 125 6.6.1 Theory ... 125 6.6.2 Practice ... 126 6.6.3 Future Research ... 126
Appendix A: User Test Written Information Provided ... 135
Appendix B: User Test Verbal Information Provided ... 136
Appendix C: Participant Consent form ... 137
Appendix D: Pre-test Questionnaire ... 139
Appendix E: User Test Task List ... 140
List of Figures
Figure 2.1: CIR Concepts ... 10
Figure 2.2: Collaboration and Information Behaviour (Talja and Hansen, 2006). ... 13
Figure 2.3: Ariadne Interface (Twidale and Nichols, 1998)... 23
Figure 2.4: SearchTogether client (Morris and Horvitz, 2007) ... 24
Figure 2.5: Coagmento screen shot (Shah, 2010) ... 25
Figure 2.6: Screen shot of the Annotate! interface (Ginsburg, 1998) ... 26
Figure 3.1: DiamondTouch Sensor Array (Dietz and Leigh, 2001) ... 35
Figure 3.2: Multi-touch Sensing through FTIR (Han, 2005) ... 36
Figure 3.3: General taxonomy format (Bowman and Hodges, 1999) ... 37
Figure 3.4: Proposed taxonomy of multi-touch interaction techniques... 38
Figure 3.5: Selected multi-touch gestures for object manipulation (North et al., 2009) .... 42
Figure 3.6: Gesture sets on large touch surface (Neto and Duarte, 2009) ... 43
Figure 3.7: Example gesture set for Interactive Photo Album (Jin et al., 2004) ... 44
Figure 4.2: Gesture recognition in a multi-touch system (Khandkar and Maurer, 2010) ... 52
Figure 4.3: Proposed Architecture for CIR applications incorporating Gesture Toolkit ... 55
Figure 4.4: Basic Information Control design in Co-IMBRA ... 60
Figure 4.5: Design of the four main Information Control types in Co-IMBRA ... 61
Figure 4.6: Design of Search Information Control in Co-IMBRA ... 62
Figure 4.7: Design of Log Information Control in Co-IMBRA ... 63
Figure 4.8: Precise selection widget (Benko et al., 2006) ... 64
Figure 4.9: Main Menu Widget in Co-IMBRA ... 64
Figure 4.10: Colour Coding Widget in Co-IMBRA ... 65
Figure 4.11: On Screen Keyboard Widget ... 66
Figure 5.1: Participant Demographics (n=30) ... 96
Figure 5.2: Team Demographics (n=15) ... 98
Figure 5.3: Proportion of teams successfully completing x tasks (n=15) ... 99
Figure 5.4: Time on task averagcd across groups (n=15) ... 99
Figure 5.5: Cumulative task times for best team, worst team and the average (n=15) .... 100
Figure 5.6: User Satisfaction Results Summary (n=30) ... 104
Figure 5.7: Mean 7-point Likert scale ratings for Section A: Cognitive Load (n=30) ... 105
Figure 5.8: Mean Likert scale ratings for Section B: Overall Satisfaction (n=30) ... 106
Figure 5.9: Mean Likert scale ratings for Section C: Usability (n=30) ... 107
Figure 5.10: Mean Likert scale ratings for Section D: Collaboration (n=30) ... 108
List of Tables
Table 2.1: Eight challenges for groupware developers (Grudin, 1994) ... 17
Table 2.2: Classification of collaboration by location and time ... 18
Table 2.3: General functional requirements of a CIR system ... 19
Table 2.4: General non-functional requirements of a CIR system ... 21
Table 2.5: Comparison of CIR systems by classification of Section 2.6.4 ... 28
Table 2.6: Comparison of CIR systems by functional requirements of Section 2.6.5 ... 29
Table 3.1: Proposed mapping of CIR tasks to multi-touch interaction techniques ... 48
Table 4.1: Data attributes for Information Control and functional requirement supported 57 Table 4.2: Information Controls and Functionality ... 58
Table 5.1: Metrics for quantifying collaboration on computationally-enhanced tables (Morris and Winograd, 2004) ... 84
Table 5.2: Summary of evaluation techniques for multi-touch systems ... 88
Table 5.3: Summary of tasks and tested functional requirements ... 101
Table 5.4: Cronbach's alpha coefficients for reliability for each section (n=30) ... 103
Table 5.5: Positive themes and frequencies identified in user comments (n=30) ... 111
Dedication
This dissertation is dedicated to my late grandmother, Kathleen Agnes Sams. I know it would have earned me a place on your mantelpiece.
Glossary and Abbreviations
Annotate! CIR tool to add collaborative dimension to a web search (Ginsburg, 1998)
API Application Programming Interface
Ariadne CIR interface presenting search queries graphically as virtual cards (Twidale and Nichols, 1998)
ATM Automated Teller Machine
Awesomium A windowless web browser framework
Cerciamo CIR system enabling synchronous, collaborative search of document collections (Golovchinsky, Adcock, Pickens, Qvarfordt and Back, 2008)
CF Collaborative Filtering
CIB Collaborative Information Behaviour CIR Collaborative Information Retrieval CIS Collaborative Information Sharing
Coagmento A CIR framework supporting collaborative information sharing, synthesis and sense-making (Shah, 2010)
CoE The Telkom/NMMU Centre of Excellence
Co-IMBRA Collaborative Information Manipulation, Browsing, Retrieval and Annotation (A multi-touch CIR prototype developed in this research) CSCW Computer Supported Cooperative Work
CSV Comma Separated Value
FSA Finite State Automata
FTIR Frustrated Total Internal Reflection GBI Gesture Based Interaction
GIS Geographical Information System(s) GDL Gesture Definition Language
GUI Graphical User Interface
HCI Human-Computer Interaction
HIB Human Information Behaviour
IDE Integrated Development Environment
IM Instant Message/Messaging
IR Information Retrieval
IV Information Visualisation
NMMU Nelson Mandela Metropolitan University
OSK On Screen Keyboard
RCD The NMMU Research Capacity Development office
SDG Single Display Groupware
SDK Software Development Kit
SearchTogether CIR system allowing remote users to collaboratively search the web(Morris and Horvitz, 2007)
TUIO Tangible User Interface Protocol
UI User Interface
WPF Windows Presentation Foundation
Introduction
Chapter 1:
1.1 Background
Collaborative work involves several users working with the same information (Hansen and Järvelin, 2005). Collaborative Information Retrieval (CIR) is the branch of Computer Supported Collaborative Work (CSCW) which deals with searching for, retrieving and viewing data as a group of people, assisted by computer systems. CIR may be defined as an information access activity that involves people interacting with other people directly and using documents as information sources, in an information seeking and retrieval process. CIR can occur in co-located environments, where collaborators are in the same physical room, or across networks. CIR can occur synchronously (at the same time) or asynchronously. Groups of people working together in a synchronous, co-located environment may refer to either hard copies of documents or to shared electronic sources (Stewart, Bederson and Druin, 1999). While it is possible to use personal computer systems in such an environment, the nature of single display and input systems does not effectively promote collaboration as personal computers are designed for single user, single input environments.
Multi-touch surface computing has risen to prominence over the last few years (Buxton, 2009). Several researchers have developed technologies using different hardware principles to sense multi-touch input on a display. This has resulted in a reduction in the cost of multi-touch sensing. The relatively low cost of modern multi-touch sensing has resulted in the development of multi-touch systems such as the Mitsubishi DiamondTouch (Dietz and Leigh, 2001) and Perceptive Pixel (Han, 2005). This has prompted research into novel ways of interacting with these systems and developing effective interaction techniques for use with multi-touch technology. There are still some limitations associated with multi-touch interaction techniques, however. These include the limited touch resolution afforded by a finger (Albinsson and Zhai, 2003), the limitation in the minimum size of the display that can be comfortably used (Forlines and Shen, 2005) and distinguishing between different actions such as select, move, etc. (Hancock, 2007). Touch screen interaction affords opportunities for gesture based interaction (GBI), and
some research has been done into employing multi-touch GBI in an environment with multiple simultaneous users (Morris, Huang, Paepcke and Winograd, 2006).
Multi-touch displays can be mounted horizontally rather than vertically to become table-top or “surface” computers. Surface computing allows access to the multi-touch screen from any position around the table. Multi-touch surface computing is opening up possibilities for new interaction paradigms (North et al., 2009). The inherently multi-user nature of multi-touch surface computing makes it ideal for CSCW. It also opens up new possibilities for interaction metaphors, such as virtual sticky notes (Robinson, 2008). Usability studies have shown object manipulation to be more effective when supported using a computer with a multi-touch surface than using physical documents without a computer (North et al., 2009).
Despite the potential advantages of multi-touch surface computing for CIR, most of the research in this area has not related to everyday, general or office use (Wigdor, Perm, Ryall, Esenther and Chia, 2007). The increased frequency of use and reduction in costs suggest multi-touch as a possible solution for effectively supporting CIR. Existing interaction techniques could be adapted and enhanced for use in this domain. While some research has been done with regard to the effectiveness of multi-touch interaction for CSCW, several questions remain as to its effectiveness when applied to CIR.
1.2 Problem Statement
The problem statement for this research is:
CIR is currently not effectively supported by multi-user systems.
1.3 Thesis Statement
The thesis statement for this research is:
The use of multi-user, multi-touch interaction techniques can effectively support CIR.
1.4 Research Objectives
To investigate the requirements for CIR as well as problems and shortcomings with existing CIR techniques and tools.
To investigate how multi-touch interaction can be incorporated into a co-located collaborative environment.
To develop a prototype incorporating improved multi-touch interaction techniques to support CIR.
To evaluate the effectiveness of the proposed techniques by evaluating the prototype.
To make recommendations for the design of future CIR systems and improvements to the proposed multi-touch interaction techniques for CIR.
1.5 Research Questions
What are the problems/shortcomings with existing CIR techniques and tools? How can multi-touch interaction be incorporated into a co-located collaborative
environment?
How can a prototype incorporating multi-touch interaction techniques be developed to support CIR?
What are the benefits of using the proposed multi-touch interaction techniques to support CIR?
How should future CIR systems be designed and what research should be undertaken to improve multi-touch interaction techniques for CIR?
1.6 Scope and Constraints
The scope of this research will be limited to collaboration in a synchronous, co-located environment. Multi-touch will be considered as the only input device, without making use of keyboards, mouse, voice recognition or video camera. New interaction techniques will not be developed as the focus will be on adapting and improving multi-touch interaction techniques for use in the domain of CIR.
1.7 Research Methodology
A positivist philosophy will be applied in this research, since the success of this study lies in measuring the effectiveness of the proposed multi-touch techniques to support CIR. A deductive approach will be followed and this research will make use of an experimental research strategy. The four main stages described in the following four subsections
describe the research strategy that will be used to address the research questions presented in the previous section.
1.7.1 Literature Study
The research will begin with a comprehensive literature study over two chapters in the dissertation. These two chapters will correspond to the two fields of interest to which this study relates. The first field of interest is CIR, with specific focus on synchronous, co-located CIR. The nature of the proposed solution justifies this emphasis, as it will be implemented on a multi-user touch surface, requiring users to be co-located. The tasks required for CIR will be identified in this literature study.
The second field of interest is multi-touch interaction. The literature study will review the existing multi-touch techniques available for use and how they have been applied in similar application domains. In particular, multi-touch interaction techniques that correspond to the CIR tasks identified in the previous chapter will be compared. Problems and shortcomings with the existing techniques will be discussed to provide a basis for applying them to a CIR application.
1.7.2 Analysis and Design
An application architecture to support CIR will be proposed, based upon the multi-touch interaction techniques discussed in Chapter 3. The solution will take the form of a prototype utilising multi-touch interaction techniques. Suggestions for the improvement of existing techniques will also be made based on the literature study.
1.7.3 Prototype
The design and implementation of a proof-of-concept prototype will follow the analysis and design of a multi-touch CIR architecture. This prototype will be used to analyse and evaluate the proposed multi-touch interaction techniques. The prototype will consist of a fully functional CIR application and will be implemented on a multi-touch surface. This will provide a platform for designing an evaluation of the proposed techniques.
1.7.4 Experiment
The prototype will be evaluated in order to determine whether or not the multi-touch interaction techniques effectively support CIR. The experiment will comprise a usability evaluation based on existing evaluation methods for CIR. Software performance metrics
will also be selected to determine the effectiveness of the proposed techniques. Additionally, methods to determine the extent to which the prototype supports collaboration will be identified. Once appropriate evaluation techniques have been determined, the prototype will be evaluated using these techniques. The results of the evaluation will then be presented and the conclusions of the research inferred from these results.
1.8 Dissertation Outline
The dissertation will follow the selected research methodology, and as such the outline of the chapters is based on the previous section.
1.8.1 Chapter 1: Introduction
The dissertation has begun by contextualising the research against the background of the broader field of CSCW. The situation of concern will be highlighted, which will be used to identify research objectives and research questions. The scope of the project will also be clearly defined. The research methodology to be followed will also be discussed in this chapter.
1.8.2 Chapter 2: Collaborative Information Retrieval
Chapter 2 is the first of two literature review chapters. This chapter will discuss the current literature in the field of CIR, beginning by defining the terminology used. The tasks required for supporting CIR will be derived along with the functional and non-functional requirements of a CIR system. The benefits as well as the shortcomings of using CIR systems will be identified. Existing systems to support CIR will be discussed, compared and evaluated to see how each system supports CIR.
1.8.3 Chapter 3: Multi-Touch Interaction
This second literature review chapter will investigate multi-touch interaction as a possible solution to the shortcomings of existing CIR systems. It will begin by briefly looking at the various multi-touch technologies, their advantages, disadvantages and usage. Existing multi-touch interaction techniques will then be identified and described, including techniques for gesture-based interaction. Shortcomings of multi-touch interaction will also be identified. The functional requirements for CIR will then be mapped onto these
1.8.4 Chapter 4: Design and Implementation
Having identified the shortcomings of current CIR systems and identified possible solutions by looking at multi-touch technology, this chapter will design a prototype as a proof-of-concept. An application architecture to support CIR will be proposed which incorporates the multi-touch interaction techniques identified in Chapter 3. The prototype will then be designed in terms of the data and user interface. The design of the interaction techniques will be described and motivated. A motivation for the usage scenario will be given. The software tools and development methodology will be described and motivated. The prototype will then be implemented. The implementation will be discussed in this chapter. A description of any issues encountered during implementation will also be presented.
1.8.5 Chapter 5: Evaluation
This chapter will begin with a brief review of relevant methods for usability evaluation in the fields of CIR and multi-touch interaction to guide the selection of appropriate evaluation techniques. The goals of the evaluation will be clearly defined. The selected evaluation methods will be described including their objectives, instruments, participants and test procedure. The proof-of-concept prototype will be evaluated using these techniques. The results of the evaluation will then be presented and analysed.
1.8.6 Chapter 6: Conclusion
In this final chapter, the project will be critically examined to see if it achieved its original research objectives. The research contribution will be analysed on both a theoretical and practical level. Limitations and problems encountered during development will be discussed. Finally, recommendations will be made for future design of multi-touch interaction techniques for CIR as well as for future research in this area.
1.9 Conclusions
This chapter provided a brief overview of CIR, which is the problem domain of this research. The possibility of using multi-touch interaction techniques to effectively support CIR was identified. The problem statement was described and the thesis statement was formulated as follows:
The use of multi-user, multi-touch interaction techniques can effectively support CIR.
The next two chapters comprise the literature review. The first chapter investigates CIR and the second considers multi-touch interaction as a potential means to support CIR.
Collaborative Information Retrieval
Chapter 2:
2.1 Introduction
This chapter is the first of two literature review chapters. The literature review begins with a study of the problem domain, which is Collaborative Information Retrieval (CIR). This chapter first defines its aim by outlining the research questions it will attempt to answer. CIR is a multi-faceted concept and there are conflicting definitions used by researchers in this field. At the outset of this chapter, the terminology that will be used will be given and defined. Aspects of CIR which are of particular relevance to this research will be identified, explored and put into context. The requirements for CIR will be identified and specific tasks that are performed during CIR will be identified. Current tools to support CIR will be looked at and their advantages and disadvantages will be considered. This chapter will provide a foundation for the next chapter to consider the possible use of multi-touch interaction to effectively support CIR.
2.2 CIR Research Questions
This chapter will answer the following research questions relating to CIR:
What is CIR?
What are the applications of CIR? What tasks are performed in CIR?
What are the objectives of and requirements for CIR? What current software tools exist to support CIR? How effectively do the current tools support CIR? What aspects of CIR can be improved?
Each research question will be addressed in the following subsections of this chapter.
2.3 Definitions and Overview
This section will define the key concepts in CIR, namely Computer Supported Cooperative Work (CSCW), Groupware, CIR and Collaborative Information Sharing (CIS).
2.3.1 Computer Supported Cooperative Work
The branch of study which deals with using computer technology to enable collaboration is called Computer Supported Cooperative Work (CSCW). CSCW can be defined as a computer-assisted coordinated activity, such as communication and problem solving, carried out by a group of collaborating individuals (Baecker, 1993).
2.3.2 Groupware
Groupware is the name given to the class of computer programs that enable CSCW (Baecker, 1993). The name derives from the multi-user nature of groupware. Groupware may be distributed across a network or with individual displays for each user.
Single-display groupware (SDG) interacts with the users of the software on one Single-display. SDG
enables co-located users sharing a single computer to collaborate with one shared display and the simultaneous use of multiple input devices, or in the case of a multi-touch screen, a single multi-user input device. The use of a single display most accurately reflects how computers are used today (Stewart et al., 1999).
2.3.3 Collaborative Information Retrieval
CIR involves collaborators interacting with each other in an information access activity (Hansen and Järvelin, 2005). It covers a broad range of collaborative tasks such as information handling, information searching and retrieval via search engines and databases, collaborative information sharing and collaborative information visualisation (IV). Collaborators may interact with one another directly and make use of shared documents as information sources, in an information seeking and retrieval process.
Definitions of CIR vary depending on the discipline, which may emphasise information handling, search and retrieval, or interaction with the information. In general, CIR may be considered as “the study of the systems and practices that enable individuals to collaborate during the seeking, searching and retrieval of information” (Foster, 2006). Fidel, Pejtersen, Cleal and Bruce (2004) noted that although there are many instances where people look for information together (a librarian helping someone locate a book), collaboration is defined to be strictly between colleagues (for example, two librarians working together). The authors also noted that CIR was not necessarily confined to information retrieval, but often involves information sharing when the information is
same work process collaborated to resolve an information problem that required them to use resources external to their own knowledge.”
Figure 2.1: CIR Concepts 2.3.4 Collaborative Information Sharing
Collaborative Information Sharing (CIS) is an important aspect of CIR, which covers a range of collaborative information behaviours whereby information is shared between members of a group or team. Some authors consider information sharing to include the ad-hoc sharing of accidentally encountered information as well as systematic query formulation and retrieval (Talja, 2002), while others consider it to refer specifically to the sharing of already acquired information (Hansen and Järvelin, 2005). In this dissertation, CIR will refer to the searching for and retrieval of information while CIS will refer exclusively to the sharing of already acquired information. CIS can be classed into document-based or human-related information sharing (Talja and Hansen, 2006).
Computer Supported Cooperative Work (CSCW)
Collaborative Information Retrieval (CIR)
Collaborative Information Sharing
Strategic Sharing
Paradigmatic Sharing
Directive
Talja (2002) identified four types of information sharing practices from studying information sharing in academic communities. These can be considered sub-types of CIS (Figure 2.1).
2.3.4.1 Strategic information sharing serves a broader purpose or goal. An instance of
strategic information sharing is the centralising of information searching tasks to maximise the efficiency of a research group. Strategic sharing is thus goal-oriented. It is also one-directional sharing, from the information seeker to the information users.
2.3.4.2 Paradigmatic information sharing establishes a research approach and an initial
understanding in a field, shared between collaborators. It is goal-oriented in the same way as strategic sharing, but often results in temporary groups gathered around a specific area of information. It can involve one-way or two-way sharing.
2.3.4.3 Directive information sharing focuses on two-way information sharing, where
both (or all) parties benefit from the results of each other’s information. This occurs when they have mutual interests or goals, and can thus be considered goal-oriented. Directive sharing often involves directing others to the information source rather than sharing the information content itself.
2.3.4.4 Social information sharing involves the sharing of encountered information with
others. Social sharing is not goal-orientated; rather it develops social relationships in the work community. Social sharing can be one-way or two-way.
This classification of CIS suggests that certain kinds of CIS may be more suited to being supported by multi-user computer systems. Goal-oriented sharing is more suited to computer support since CSCW can be considered a relatively formal form of cooperation. Social information sharing will not be considered in this research. Directive information sharing, being two-way, is clearly more suited to a multi-user system than strategic or paradigmatic sharing, and will be the focus of this research.
2.4 Applications of CIR
Foster (2006) describes CIR in academic, industrial, medical and military settings. He identifies several application domains in computer science in which CIR is an important component. Any application domain that is multi-user can be considered to contain a
Typical areas for CIR research are general search engines, collaborative querying of databases and sharing of documents.
Academic applications of CIR include collaborative research, co-authoring of papers, academic administration and group learning. Academic applications of CIR tend towards high data intensity and require good support for ensuring awareness.
Poltrock, Fidel, Bruce, Grudin, Dumais and Pejtersen (2003) studied CIR in an industrial setting, namely collaboration between members of a design team. They found that oral communication was the preferred method of communication between the team, which highlights the value of synchronous CIR in this setting.
Medical practitioners find collaboration particularly useful in information seeking and retrieval. In medical environments, practitioners frequently use handwritten notes and annotations to aid collaboration when seeking information about a patient (Ash et al., 2001).
In military settings, it is vital that all members of a command team have a shared understanding of a mission. The commander plays an important role in identifying critical information needs. Research has found that in a military team, team goals were supported by a shared situation awareness and dense social networks which support frequent, bi-directional information flow amongst team members (Foster, 2006).
A general CIR system could support CIR in all of these settings. Medical and military settings would require the most specific support. In addition the high data intensity and highlighted need for synchronous support encourages a focus on academic or industrial settings.
2.5 Tasks Required for CIR
Collaborative Information Behaviour (CIB) is emerging as a new direction for Human Information Behaviour (HIB) research (Talja and Hansen, 2006). CIB investigates the behaviour of groups of people communicating to identify information used in solving a problem or completing a task. CIB can help define the tasks that are generally required for CIR by looking at the activities that group members perform during a collaborative task. Figure 2.2 depicts the general organisation of collaborative information behaviour in a cultural, social or organisational context. The part of the figure within the dotted line
shows the stages of a collaborative task. Collaboration can occur at all stages of a task or situation, from initiation to completion. Computers are especially useful to facilitate information seeking and information retrieval. CIB includes “processes of problem identification, analysis of information need, query formulation, retrieval interactions, evaluation, presentation of results, and applying results to resolve an information problem”.
Foster (2006) divides CIR tasks into two broad categories: Information seeking and information navigation. Within information seeking, he describes collaborative querying and collaborative filtering. Within information navigation, he describes social data mining and history enriched digital objects. Navigation of information is equivalent to the information retrieval task shown in Figure 2.2.
2.5.1 Information seeking or searching
Information seeking can be defined as the process whereby information is found via querying and filtering tasks (Foster, 2006). Both these tasks can be performed as a collaborative effort and can thus be considered part of CIR.
Collaborative Querying (CQ) is a technique whereby users of an information retrieval
system can draw on the past query preferences of other users. CQ can be achieved automatically by applying algorithms to previous search logs. Collaborators can also make use of manually entered contextual information such as ratings. A synchronous element to CQ can be introduced through the implementation of discussion facilities during query refinement or, for example, with the addition of a query management system.
Collaborative Filtering (CF) can be divided into two sub-topics – active CF and
automated CF. Active CF involves users specifying criteria, such as keywords or other users’ ratings, which filter the relevant data from the search results. This form of filtering can be synchronous, with multiple users actively filtering data together, or asynchronous, where the filtering is done based on past user experiences. Automated CF recommends or ranks search results based on the past reactions of users. This form of filtering is naturally asynchronous.
2.5.2 Information Retrieval
The paths that users take when navigating through data can be used to support CIR (Foster, 2006). Viewing information spaces as dynamic and not definite in location, social navigation can help users find more efficient ways of retrieving information since social navigation provides the most recent data on the state of the information space. Tools to support navigation of information can be broadly categorised into asynchronous and synchronous tools. Asynchronous navigation falls outside the scope of this research.
Synchronous social navigation can be supported by providing tools such as chat during information seeking. In a co-located environment, mechanisms can be provided that also highlight which objects have been given attention by other users, to improve awareness of other users’ actions.
2.6 Components and Requirements of CIR
This section begins by motivating a need for systems to support CIR. Benefits and shortcomings associated with CIR are then identified. Different classifications of CIR systems are discussed. The functional requirements of a general CIR system are then derived from the tasks required for CIR identified in the previous section.
2.6.1 Motivation for CIR
Humans frequently turn to social solutions when confronted with a task. Others may have experience, expertise or resources to solve a problem that an individual may lack. Shah (2010) identified three main reasons why people collaborate:
Requirement;
Division of labour; and Diversity of skills.
Requirement refers to the fact that in many working environments collaboration is mandatory, for example where a task has been delegated to a whole team. Division of labour between members of a team can result in greater productivity. Finally, a task may be too complex for an individual to tackle. In this case, a person may choose to collaborate with experts to create a diverse skill set in a team. CIR systems may be employed to support collaboration (Morris and Horvitz, 2007). Studies have found that CIR systems can improve awareness, division of labour and persistence of information.
2.6.2 Benefits of using CIR
Studies have shown that collaboration is common in information seeking tasks (Hansen and Järvelin, 2005). Particularly when a goal is shared, collaboration can improve efficiency by delegating tasks and avoiding repetition of information retrieval.
requires collaborators to remain aware of each other’s activities. CIR can play an important role in communicating and improving group awareness.
Division of labour occurs when group tasks are divided amongst team members to improve efficiency (Foley and Smeaton, 2010). This ensures that activities are not performed by more than one team member. CIR can also provide tools to help divide tasks between group members, such as splitting the results of a query between group members. CIR systems can also ensure that accurate records of past tasks, such as queries or searches, are kept. This ensures persistence of information, which is important for repeating tasks and remaining updated about the actions of other group members.
Electronic sources provide several benefits over physical documents (Newman and Wellner, 1992). Electronic sources allow a wide variety of interactive functionality to be included, such as searching, sharing via email, spelling correction and language translation amongst others. However, electronic sources lack the tangibility of paper documents and may therefore be less efficient to use.
2.6.3 Problems and shortcomings of CIR
Not all documents or sources are available in electronic form. Some, such as books, may only be available in a physical format which can result in inconsistencies with the computer system (Ginsburg, 1998). Some documents are also subject to copyright requirements prohibiting their electronic storage and transmission. Many users prefer to review documents on paper. Reading electronic books has been shown to increase fatigue. Many users also like the freedom of having paper documents they can read when away from a computer.
Paper documents are often the most intuitive way of sharing and annotating data and current systems may not cater to users’ desire for a natural feel when reviewing documents (Morris, Huang, et al., 2006). Working collaboratively at a traditional PC workstation does not provide intuitive collaborative interaction such as orientating the document to face another user, passing papers across a table, and making casual annotations.
Grudin (1994) describes eight challenges for the development of collaborative systems, summarised in Table 2.1. Collaborative systems are frequently underutilised because the perceived lack of benefit of using these systems. Systems may fail because they are too
complex, have a steep learning curve or because they may attract too few users to be effectively multi-user.
Table 2.1: Eight challenges for groupware developers (Grudin, 1994)
1. Disparity in work and benefit. Groupware applications often require additional work from individuals who do not perceive a direct benefit from the use of the application.
2. Critical mass and Prisoner’s dilemma problems. Groupware may not enlist the “critical mass” of users required to be useful, or can fail because it is never to any one individual’s advantage to use it.
3. Disruption of social processes. Groupware can lead to activity that violates social taboos, threatens existing political structures, or otherwise demotivates users crucial to its success.
4. Exception handling. Groupware may not accommodate the wide range of exception handling and improvisation that characterizes much group activity. 5. Unobtrusive accessibility. Features that support group processes are used
relatively infrequently, requiring unobtrusive accessibility and integration with more heavily used features.
6. Difficulty of evaluation. The almost insurmountable obstacles to meaningful, generalizable analysis and evaluation of groupware prevent us from learning from experience.
7. Failure of intuition. Developers have relatively poor intuition into the best design of multi-user applications. This results in bad project management decisions and an error-prone design process.
8. The adoption process. Groupware requires more careful implementation (introduction) in the workplace than product developers confront with single user systems.
2.6.4 Classification of CIR systems
The most common way to classify collaborative activities is based on two factors: location and time (Hansen and Järvelin, 2005). Table 2.2 shows the four classes of collaboration resulting from these two factors. Collaboration within a team may occur with the team members in the same place (co-located collaboration) or with team members distributed between offices or work areas (remote collaboration). In co-located collaborative environments, team members can converse, share documents and demonstrate ideas. In remote collaboration team members frequently turn to email, IM or telephone conversations to facilitate collaboration. Collaboration can also be classified as synchronous or asynchronous. Synchronous collaboration refers to a team working simultaneously on a collaborative task such as information retrieval. Asynchronous collaboration can occur when members keep different work hours or live in different time zones. Asynchronous co-located collaboration faces similar challenges to remote collaboration since the use of a shared work space is meaningless if team members are not there at the same time. Remote collaboration often has an asynchronous nature since members may opt to collaborate via email or other asynchronous means.
Table 2.2: Classification of collaboration by location and time
Physical Location Team members in same location Team members in different locations T ime Team members working simultaneously Synchronous, co-located collaboration Synchronous, remote collaboration Team members working at different times Asynchronous, co-located collaboration Asynchronous, remote collaboration
Collaboration can also be classified as system-mediated or user-mediated (Golovchinsky, Pickens and Back, 2008). System-mediated (or algorithmic) collaboration involves computer systems automatically distributing tasks or results while user-mediated
collaboration has one or more users distributing the workload between the group members. Co-located CIR systems generally use user-mediation as the workload is more easily divided when users are in the same location.
Collaboration can also be active (explicit) or passive (implicit) (Golovchinsky, Pickens, et al., 2008). Active collaboration occurs when users actively form a collaborative group and implies a structured collaboration where users may have specific roles. This is the most common form of collaboration in an organisational context. In passive collaboration users may not know the users they are collaborating with or even that they are collaborating at all. This occurs particularly with system-mediated collaboration across networks. Search results may be automatically sorted by relevance determined from the actions or ratings of other users.
Synchronous, co-located collaboration may be supported by multi-user computer systems. Multi-user computer systems imply active collaboration as the users will be part of the same team and highly aware of the other users’ actions. There is a lack of specialised systems for this kind of collaboration and users frequently must make use of computer systems designed for one user (Stewart et al., 1999). This research will thus focus on synchronous, co-located, active, user-mediated collaboration.
2.6.5 Functional requirements of CIR
The tasks required for CIR were identified in Section 2.4. Twelve general functional requirements of CIR have been identified, which are summarised in Table 2.3.
Table 2.3: General functional requirements of a CIR system
1. Provide shared access to an information space
2. Search by collaboratively querying and filtering the information space
3. Present or visualise the search results or shared information
4. Collaboratively navigate through and retrieve search results
6. Manipulate the search results or shared information
7. Update or add value to shared information
8. Update users on other users’ actions
9. Enable communication between group members
10. Enable division of workload between group members
11. Store logs of user actions, such as communication and searches
12. Enable users to refind and reuse information
Users of a CIR system require access to an information space, which may be a database, a set of documents, or the World Wide Web. Users search the information space using collaborative querying and/or collaborative filtering. The results need to be presented in a way that is meaningful with regard to the data. Twidale and Nichols (1998) made use of virtual cards to visualise past search results. The results can then be navigated through to retrieve a document. The representations of the results may be manipulated to order or categorise the information. The information may also be updated or have value added to it in the form of annotations, ratings or automatic statistics such as number of times opened. To be an effective collaborative system a number of functions need to be supported that facilitate awareness and communication (Morris and Horvitz, 2007). Awareness of other group members’ results is essential in collaboration and in some cases sharing of information is the main goal of collaboration. Awareness of other members’ activities during the information retrieval process is important to reduce duplication of effort and to promote learning of information retrieval techniques (such as effective querying) from other members. The system should keep users updated about each other’s actions, enable communication between them, such as with integrated IM.
Persistence of information is a related concept to awareness. Persistent information is information that is stored for later access by a group member, which facilitates greater awareness amongst the team of each other’s and their own activities. Users of systems without strong persistence of information may find themselves entering a search term multiple times in order to re-find information (Teevan, Adar, Jones and Potts, 2006) to ensure the persistence of information found and generated through the use of the tool, actions should be logged and queries and filters stored to enable users to refind and reuse information that has been found previously.
Division of labour can be supported by dividing tasks, keywords or concepts between team members (Amershi and Morris, 2008). Manual division of labour is a communication-intensive process and requires team members to converse or use email, IM or the telephone. One method to support division of labour is using ratings and recommendations of documents to bring important information to the attention of other group members (Turnbull, 2007).
2.6.6 Non-functional requirements of CIR
Shah (2010) identified three primary goals prior to the development of the Coagmento collaborative system, namely simplicity, integration and flexibility. These three goals were identified as non-functional requirements for a CIR system, as summarised in Table 2.4.
Table 2.4: General non-functional requirements of a CIR system
Requirement Description
Simplicity Collaborative systems in particular should be simple to promote learnability and memorability.
Integration All the various elements of a collaborative system should be integrated into one interface
Flexibility Collaborative systems should be designed to be flexible to the preferences of different groups.
methods of enabling collaboration if a system will not cater to their needs or if it is too difficult to use.
There are several elements to a system enabling collaboration, such as communication and search results. Integration of all the elements in a single interface is important to reduce the cognitive pressure of switching between the various tools (Morris and Horvitz, 2007)
2.7 Tools to support CIR
Several researchers have noted the lack of specialised tools to support CIR (Shah, Marchionini and Kelly, 2009). Methods and tools used for CIR have not changed greatly since their inception. Although several novel tools to support CIR have been proposed, none have become widely used or recognised. In co-located, synchronous environments shared use of a personal computer is common. In these environments conversation is the simplest form of collaboration. When collaborators are remote, general purpose communication, such as email, instant messaging (IM) and telephone calls are the preferred methods of supporting collaboration (Morris and Horvitz, 2007). Five of the most important tools that have been developed for supporting CIR are described here: Ariadne, SearchTogether, Coagmento, Cerciamo, and Annotate!. These tools are reviewed below.
2.7.1 Ariadne
Twidale and Nichols (1998) describe a prototype interface, Ariadne, to support CIR using a graphical representation of search queries that can be manipulated and discussed by users. Ariadne takes advantage of the knowledge of the users. The researchers found that their system was more robust and adaptable than using an intelligent interface on its own. The domain of their research involved many users performing searches with the help of a small number of expert users. This is illustrated by the example of library users consulting librarians to help them find the information they are looking for. Recording the search actions proved advantageous so users can remember what has been tried and demonstrate their actions to other users. The Ariadne interface (Figure 2.3) uses a series of virtual cards to represent searches. Each contains a thumbnail image of the search results to remind users of the previous searches. Clicking on the card expands the information to show the previous results.
Figure 2.3: Ariadne Interface (Twidale and Nichols, 1998)
The Ariadne interface, although an early example, demonstrates that visualising search results can improve collaboration by providing virtual objects that can be manipulated and discussed by users of the system. Providing objects that can be manipulated may be a more intuitive form of interaction with a collaborative system.
2.7.2 SearchTogether
SearchTogether is a more recently developed application that allows groups of remote people to collaboratively search the web (Morris and Horvitz, 2007). It supports both synchronous and asynchronous collaboration. The researchers motivated their tool with a survey of 204 knowledge workers to investigate current web search practices. The survey showed that the most common tools used in collaboration were emails, instant messages and phone conversations which could take place concurrently with the searching process. The researchers used these facts to motivate the design of SearchTogether, which incorporates IM as a tool to support collaboration.
SearchTogether uses histories of queries and page visitations together with ratings and comments to improve awareness. Clicking on a past query produces the results of the query from when it was executed, resulting in immediate and interactive access to past queries, to enable users to refind information. SearchTogether also displays page-specific metadata, including group members who visited their page together with their comments and ratings, which can help both to indicate important sites. Section 2.6.2 highlighted the importance of supporting awareness in CIR tools to reduce duplication of effort. Figure 2.4 shows a screenshot of the SearchTogether client (Morris and Horvitz, 2007).
Figure 2.4: SearchTogether client (Morris and Horvitz, 2007)
(a) IM, (b) query awareness, (c) current results, (d) recommendation queue, (e)(f)(g) search buttons, (h) page-specific metadata, (i) toolbar, and (j) browser
2.7.3 Coagmento
Shah (2010) presented Coagmento, a framework for supporting collaborative information seeking, synthesis and sense-making. Coagmento was designed to address the challenge of providing additional support to collaborators having found information and striving to synthesise and make sense of the information. Coagmento consists of a browser plugin, which includes a toolbar and a sidebar, and CSpace, an online collaborative space.
Coagmento provides functionality to collect, share, recommend, refind and reuse information. Value can be added to the information by the users in the form of ratings and notes. CSpace is a web based area designed to support information synthesis, where information can be organised and reports compiled to summarise the information. Figure 2.5 shows a screen shot of the Coagmento interface, illustrating the toolbar, sidebar and CSpace home page.
Figure 2.5: Coagmento screen shot (Shah, 2010) 2.7.4 Cerciamo
Cerciamo is a system that enables the synchronous, collaborative search of document collections (Golovchinsky, Adcock, et al., 2008). Cerciamo uses a unique method for dividing labour between users by their role in the group. Users are divided into two different roles, namely Prospectors and Miners. Prospectors discover potentially promising directions of exploration, whereas Miners follow these directions deeper into the results. Different interfaces are provided for these two different roles and a third interface provides a shared display of the progress of the session. Documents are presented to the Prospector in a list, on which queries and relevance judgements can be made. The Prospector’s role is to cover as much of the search space as possible. The Miner’s queue is
influenced by the Prospector’s efforts and is continually reordered in terms of the relevance associated with the documents by the Prospector.
2.7.5 Annotate!
Ginsburg (1998) describes Annotate!, a tool to add a collaborative dimension to a web search. Annotate! allows multiple participants to discuss single author documents, adding meta-information to documents that facilitates the searches of other users. Figure 2.6 shows the Annotate! interface. Annotate! assists collaborators by providing clues to the content of a document without having to open it. It also helps information persist by storing the associations that users have made between related web pages.
2.8 Comparison and Evaluation of CIR systems
The above systems were designed with different application domains in mind and with different goals. All these systems were designed for a CIR application however, and can be evaluated against the general requirements for CIR systems. Having identified the key requirements of CIR in Section 2.6.5, the five systems were compared using these requirements. Table 2.5 classifies the systems according to the criteria in Section 2.6.4. Most of the systems were remote, user-mediated, active systems. Only one system was exclusively co-located and only one was exclusively passive. There were a similar number of synchronous and asynchronous systems.
Table 2.6 summarises the comparison between the systems and indicates those features of the systems that support the functional requirements. Three of the five systems use the World Wide Web as an information space and utilise existing search engines to search the information space.
One system presents the results as virtual cards which supported manipulation, while the others present the results in a list which allows a greater number of results to be displayed. A combined list of virtual objects could take advantage of the benefits of each. The systems did not display good support for collaborative navigation through the results. A co-located system could provide better support for this type of collaboration.
All but one of the systems support the ability to add value in the form of ratings and annotations. This also assists in keeping users updated on other users’ actions. In addition, three of the five systems keep logs of previous actions to allow users to refind and reuse information.
The systems vary in their application but the above common functionality can be used to inform the design of a co-located, synchronous, user-mediated, active CIR system. The only system that was investigated that falls under this classification was Ariadne, which is not a recent system.
T a ble 2 .5 : Co mp a riso n o f C IR sy st em s by cla ss if ica tio n o f Sect io n 2 .6 .4 Ann ot at e! ( 1998) R emot e Async hr onous S ystem -media ted P assi ve Ce rc h iamo (2008 ) Co -loca ted or R emot e S ync hr onous Use r a nd S ystem -media ted Ac ti ve Coagm en to ( 2010) R emot e S ync hr onous or asynch ronou s Use r-media te d Ac ti ve S ear ch T oge ther (2007 ) R emot e S ync hr onous or asynch ronou s Use r a nd S ystem -media ted Ac ti ve a nd P assi ve Ar iad n e ( 19 98) Co -loca ted S ync hr onous Use r-media te d Ac ti ve L oc at ion T ime M ed iation T yp e of Collab or at ion
