Collaborative writing and editing typically use annotations to coordinate edition tasks, comment the content, add relevant references, or clarify confusing content. Despite that wikis are among the most widely used hypertext systems for performing such collaborative activities, they have little support to annotations. In this paper, we propose to use spatial hypertext layers as the solution for the management of annotations in wikis. We have extended ShyWiki, a spatial hypertext wiki environment, with Multilayer Superimposed Information features. In addition, we present the results of a study that shows the value of spatial hypertext layers for locate, organize and group annotations in interest groups under a wiki interface.

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Multilayer Superimposed Information for
Collaborative Annotation in Wikis
Carlos Solis, Jose H. Canos and
Marcos R.H. Borges
Carlos.Solis@lero.ie

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Table of Contents
• Motivation
• Related Work
• Requirements
• Spatial Hypertext Wiki (ShyWiki)
• Superimposed Information in ShyWiki
• Conclusions
• Future Work

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Motivation: Annotations

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Motivation: Wikis

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Motivation
Collaborative annotation is part of many
information management activities.
In Annotative Collaboration Processes authors
and editors use annotations to edit, review and
evolve documents, as well as in the coordination
of the goals, tasks, resolution of conflicts, etc.

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Motivation
How can we annotate in a wiki?
• The discussion page can be used as a kind of
annotation.
• Text between brackets if often used to
annotate the content.

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Requirements
General requirements (Murthy, 2004):
• The management of the annotations must be
simple.
• The superimposed information data model
must be able to represent many data models
• No assumptions must be made about the
content being annotated.

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Requirements
Specific requirements:
• Add notes to a wiki page.
• Add several layers of annotations
• View only the original information.
• View selected layers of annotations.
• Move annotations between layers.
• Organize the layers by user interest groups.

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Related work: Open hypermedia
• Open hypermedia systems Microcosm,
Chimera, Annotea, Fluid documents allow to
extend documents with annotations and
hyperlinks.

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Related Work: Spatial Hypertext
Tinderbox
Visual Knowledge Builder
VIKI, VKB, WARP, Tinderbox

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Related Work: Spatial Hypertext
• Spatial hypertext has not been used in
collaborative systems such as wikis (before
ShyWiki).
• Spatial Hypertext might have the problem of
information overload.

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Superimposed Information Spatial
Hypertext

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ShyWiki

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Multilayer Superimposed
Information ShyWiki Model

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Multilayer Superimposed
Information ShyWiki

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Interest Groups
The superimposed information layers can be
associated to the individuals and groups.
A user subscribes to a layer name in order to
view the superimposed information layers with
the same name when she or he navigates
through the wiki.

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Layer Filtering
Wiki page allows the possibility of filtering the
content:
•Users can select a set of superimposed
information layers to visualize.
•User can display only the base layer.

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Superimposed information
management operations
•Add layer. Adds a superimposed information layer to a wiki
page.
•Remove layer. Removes a superimposed information layer
including all its notes.
•Add note. Adds a note to a superimposed information layer,
by default notes are added to the base level.
•Move note. Moves a note to a superimposed information
layer.
•Move all. Moves all the notes in a superimposed information
layer to another.

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Evaluation
• 18 subjects split into two groups, one group
used ShyWiki with spatial hypertext layers,
and the other without layers. The null
hypothesis is that the experimental group
would perform better.
• Both groups interacted with a wiki page which
content was the same. In the first task they
counted the number of annotations, in the
second they counted the number of sets of
annotations, and in the third they counted
how many annotation were in each set.

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Evaluation
• Q1. How many annotations are?
• Q2. How many sets of annotations are?
• Q3. How many annotations are in each set?
• Likert
– S4. It is useful to have annotations
– S5. The annotations are intrusive
– S6. The annotations are distinguishable
– S7. The annotations are easy to locate
– S8. It would be useful to be able to hide or show the annotations
– S9. It is useful to have sets of annotations
– S10. It would be useful to filter the annotations by set
– S11. It would be useful to subscribe to annotation sets
– S12. A wiki page should show the annotations sets you are subscribed

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Discussion
•The experimental group was able to locate all the annotations in a more effective way
(one tailed p-value, 0.041).
•Users in the experimental group were able to locate in a more effective way the sets
annotations and the notes that belong to those sets (one tailed p-value is 0.029).
•The effectiveness in the experimental group was 88% against 44% in the control one.
•The times to find the answers were better for the experimental group in all tasks.
•All users believe that annotations are useful.
•Spatial annotations were more intrusive, but easily distinguishable, and easier to
locate.
•User agree that would be useful to be able to hide or show the annotations, having
sets of annotations and subscriptions.

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Conclusions
• Superimposed spatial hypertext provides support to
annotation in wiki systems.
• The use of layers permits to have different views of
the information, and create hyperlinks to these
views.
• Users are willing to annotate the content, and to
know the annotations that are performed by users
with similar interests
• Spatial hypertext layers help users to organize and
locate the annotations in a better way than a wiki
without superimposed information support.

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Future Work
• Explore the relations between layered spatial
hypertext interfaces and multidimensional hypertext
(ZigZag and Xanadu).
• Analyze how the superimposed information layers
are used.
• Support independent and parallel sub-group work.
• Look if the layers can be used to manage an edition
process.

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Thank you!
Questions?