*Current address: Dept. of Computer Science, Chalmers University of Technology, S-412 96 Göteborg, Sweden
This paper offers new principles for visual information
seeking (VIS). A key concept is to support browsing, which is
distinguished from familiar query composition and information
retrieval because of its emphasis on rapid filtering to reduce
result sets, progressive refinement of search parameters, continuous
reformulation of goals, and visual scanning to identify results.
VIS principles developed include: dynamic query filters (query
parameters are rapidly adjusted with sliders, buttons, maps, etc.),
starfield displays (two-dimensional scatterplots to structure
result sets and zooming to reduce clutter), and tight coupling
(interrelating query components to preserve display invariants
and support progressive refinement combined with an emphasis on
using search output to foster search input). A FilmFinder prototype
using a movie database demonstrates these principles in a VIS
query, dynamic queries, information seeking, tight coupling, starfield
In studying visual information seeking (VIS) systems
for expert and first time users, we have found several user interface
design principles that consistently lead to high levels of satisfaction.
This paper defines these principles and presents a novel VIS system,
The exploration of large information spaces has remained a challenging task even as parallel hardware architectures, high-bandwidth network connections, large high-speed disks, and modern database management systems have proliferated. Indeed, these advances have left many users with the feeling that they are falling further behind and cannot cope with the flood of information [3, 18]. Now, the user interface design principles for VIS have the potential to reduce our anxiety about the flood, find needles in haystacks, support exploratory browsing to develop intuition, find patterns and exceptions, and even make browsing fun.
The key to these principles is understanding the
enormous capacity for human visual information processing. By
presenting information visually and allowing dynamic user control
through direct manipulation principles, it is possible to traverse
large information spaces and facilitate comprehension with reduced
anxiety [14,16]. In a few tenths of a second, humans can recognize
features in mega-pixel displays, recall related images, and identify
anomalies. Current displays of textual and numeric information
can be extended to incorporate spatial displays in which related
information is clustered in 2-dimensional or higher spaces. This
use of proximity coding, plus color coding, size coding, animated
presentations, and user-controlled selections enable users to
explore large information spaces rapidly and reliably.
The principles of direct manipulation were a good starting point for design of visual information seeking applications :
- visual representation of the world of action including both the objects and actions
- rapid, incremental and reversible actions
- selection by pointing (not typing)
- immediate and continuous display of results
However, when designing systems especially for information seeking tasks , additional principles are needed. A key VIS principle is to support browsing, which is distinguished from familiar concepts of query composition and information retrieval because of its emphasis on rapid filtering to reduce result sets, progressive refinement of search parameters, continuous reformulation of goals, and visual scanning to identify results. These goals are supported by the VIS designs developed in this paper:
- dynamic query filters: query parameters are rapidly adjusted with sliders, buttons, etc.
- starfield display: result sets are continuously available and support viewing of hundreds or thousands of items
- tight coupling: query components are interrelated
in ways that preserve display invariants and support progressive
refinement. Specifically, outputs of queries can be easily used
as input to produce other queries.
Dynamic Query Filters
Our early work on dynamic queries [2, 6, 20] demonstrated
dramatic performance improvements and high levels of user satisfaction.
By allowing rapid, incremental and reversible changes to query
parameters, often simply by dragging a slider, users were able
to explore and gain feedback from displays in a few tenths of
a second. For example, the Dynamic HomeFinder enabled users to
adjust upper and lower bounds on home prices and see points of
light on a map indicating available properties (Figure 1). This
allowed users to immediately identify high or low cost communities,
or find low cost homes in high-priced communities. Users could
similarly adjust a slider to indicate number of bedrooms, and
select toggles to indicate desire for garage, central air-conditioning,
Each of these query components (sliders, buttons, etc.) acted as a filter, reducing the number of items left in the result set. The effects were combined with simple AND logic, accounting for most naturally occurring queries. In situations where OR logic was required, users were usually quite satisfied, or actually preferred, generating a sequence of queries. This approach allowed users to see the size of the ORed components rather than merely the union of the result sets.
Figure 1: In the Dynamic HomeFinder query system
each point satisfies the query described by the sliders for location,
cost, number of bedrooms, home type (house, townhouse, or condominium),
and buttons (Garage, Fireplace, Central Air Conditioning, or New
construction). The points of light can be selected to generate
a detailed description.
The work reported in this paper advances dynamic
queries by demonstrating the efficacy of selection of items in
alphanumeric lists with the Alphaslider [1, 12]. This query component
allows users to select one item from a list of 10,000 or more,
with a simple selection tool that takes little screen space, avoids
use of the keyboard, and prevents typing errors.
In our early work on dynamic queries the output was
based on a naturally occurring spatial display. For example, the
chemical table of elements was used with color highlighting of
chemical names to indicate inclusion in the result set. In the
Dynamic HomeFinder, points of light on a map of Washington, DC
indicated properties that matched the query components. One step
in the direction of generality was to build a version of the HomeFinder
that had textual output as might be found in the tuples of a relational
database display. As the query components were adjusted, the display
remained stable, but when the user let go of the mouse button,
the screen was refreshed with the correct result set.
To further support the widespread application of
dynamic queries it seemed necessary to find other approaches to
visual information display [4, 5, 7, 17]. Points of light are
convenient because they are small yet highly visible, could be
color coded, are selectable objects, and can be displayed rapidly.
But if a natural map did not exist for an application, such as
a set of documents, photos, songs, etc., could we create one that
would be suitable? While we need to try further examples, our
initial answer is affirmative. For many situations we have been
able to create meaningful two-dimensional displays by selecting
ordinal attributes of the items and use them as the axes. This
starfield approach is a scatterplot with additional features to
support selection and zooming. Our intuitions about what choices
are most effective is still rough, but there is hope that we can
formalize our decisions.
For example, in a database of documents, the year
the document was written might be the horizontal axis while length
in words might be the vertical axis. Large old documents might
be at the upper left while short new documents might be at the
lower right. Other attributes such as an author assigned importance
value, number of co-authors, or number of references could also
be used. In a database of people, the axes might be the age, number
of years of education, salary, number of children, or other demographic
The principle of tight coupling of interface components
began to emerge in some direct manipulation graphic user interfaces.
For example, if a user saves a document, the SAVE menu item becomes
grayed out until a change is made. Tight coupling helps reveal
the software state, and often constrains the user from making
erroneous or useless actions.
A more complex example of tight coupling is the interrelationship
between the text in a word processor, the position of the thumb
in the scroll bar, and the page number displayed on the window
border. Moving the thumb causes the text to scroll and the page
number to be updated. We could write a logical proposition describing
the relationship among these three display components. Such a
statement would begin by indicating that when the top of the document
is displayed, the thumb is at the top of the scroll bar and the
page indicator is set at 1. Good program design would ensure the
preservation of the display invariants. However, some word processors
may fail to preserve this invariant when sections of the document
are deleted or when the document is reformatted with a larger
font. To compensate, some word processors may include a repaginate
command, or update the thumb position only when it is moved. These
errors violate the principle of tight coupling.
Tight coupling also applies to components of a query
facility. In a well-designed facility, users should be able to
see the impact of each selection while forming a query. For example,
if a user specifies that they want films before 1935, then only
certain actors or directors are selectable. This is to prevent
usersí from specifying null sets, e.g. films made before
1935 and directed by Francis Ford Coppola.
Another aspect of tight coupling is the linkage of
output-is-input to support efficient use of screen space
by eliminating the distinction between commands/queries/input
and results/tables/output. In short, every output is also a candidate
for input. This principle first emerged in our 1983 hypertext
work  in which the notion of embedded menus replaced the earlier
designs that had a paragraph of output followed by a menu to select
further information. It seemed more logical to have highlighted
words in the text and simply allow users to select those words
with arrow keys, a mouse, or a touchscreen. The outputs-are-inputs
principle reduced screen clutter by eliminating redundancy, and
focused usersí attention to a single location for gathering
information and for applying an action to get more information.
This principle was applied in the chemical table
of elements in which each element could be selected causing the
sliders to be set to that elementís values , in our
health statistic map in which a state could be selected to retrieve
its detailed data , and in the HomeFinder in which a point
of light could be selected to retrieve detailed information or
a photo, if it were available.
That database output can be used as input can be
compared to functionality in spreadsheets where there is no such
thing as input cells or output cells, or the Query by Example
system  where input can be treated as output and vice versa.
It has been referred to as a notion of Equal Opportunity .
In information retrieval systems this is useful as users can easily
explore branches of a search and follow their associations as
they come along -- associative database searching.
Tight coupling has several aspects:
- comprehensible and consistent affordances to guide users (highlighted words or areas, explicit handles, scrollbars, etc.).
- rapid, incremental, and reversible interactions among components.
- constraints on permissible operations to preserve display invariants (logical propositions relating the components, e.g. that the scroll bar thumb position constantly reflects the position in the document) and prevent errors.
- continuous display to always show the users some portion of the information space that they are exploring. They begin by seeing a typical result set or item, which helps to orient them to what is possible in this information seeking environment. This seems more effective than starting with a blank screen or a form to fill in.
- progressive refinement, in which users can alter the parameters to get other results . If the users see that there are too many items in the result set, they can reformulate their goal and seek a more restrictive value for one of the attributes.
- allow users to select details on demand .
This is the heart of hypermedia, but it applies to most designs.
Instead of older query facilities which required alternation between
query composition and result interpretation, our designs show
results and invite further selections if details are needed. In
the Dynamic HomeFinder, homes were shown as simple points of light
until the user selected one of the points to get the details.
This principle reduces clutter while the query is being shaped
and allows users to get further information when they need it.
To test these principles of visual information, we
created a tool for exploring a film database, the FilmFinder.
Watching a film is often a social activity so this tool was designed
to encourage discussions and make the decision process easier
for groups of viewers. Existing tools for learning about films
include encyclopedias, such as Leonard Maltin's Movie and Video
Guide . They typically provide an alphabetic organization,
with additional indexes, but these are difficult to use. Recently,
computer-based encyclopedias such as Microsoft's Cinemania have
appeared on the market. Although some of them employ novel approaches
such as hypertext links they still do not provide users with an
overview of the data. They employ a traditional approach to database
queries with commands or form fill-in, and then provide a textual
response in the form of scrolling lists. If the users are unhappy
with the result, they compose a new query and wait for the new
result. Progressive refinement can take dozens of steps and many
Before designing the tool, informal interviews were
conducted with video store clerks and film aficionados. The FilmFinder
[Color plate 1] tries to overcome search problems by applying
dynamic queries, a starfield display, and tight coupling among
components. Dynamic queries were applied by having a double box
range selector to specify film length in minutes, by having buttons
for ratings (G, PG, PG-13, R), large color coded buttons for film
categories (drama, action, comedy, etc.), and our novel Alphasliders
for film titles, actors, actresses, and directors.
The query result in the FilmFinder is continuously
represented in a starfield display [Color plate 1]. The X-axis
represents time and the Y-axis a measure of popularity. The FilmFinder
allows users to zoom into a particular part of the time-popularity
space [Color plate 2]. As users zoom in the colored spots representing
films grow larger, giving the impression of flying in closer to
the films. The labels on the axes are also automatically updated
as zooming occurs. When fewer than 25 films are visible, their
titles are automatically displayed.
To obtain more information about a particular element
of the query results, users click on that element, getting desired
details-on-demand [Color plate 3]. An information card which provides
more information about attributes such as actors, actresses, director
and language, is displayed. In a traditional retrieval system
users would obtain more information by starting a new query. In
the FilmFinder users can select highlighted attributes on the
information card and thereby set the value of the corresponding
Alphaslider to the value of that attribute. This forms the starting
point for the next query and allows graceful and rapid exploration
with no fear of error messages.
Tight coupling is strongly supported in the FilmFinder.
When users select categories of movies using the category toggles,
the starfield display and the query ranges of the Alphasliders
are immediately updated [Color plate 2]. This effectively eliminates
empty and invalid query results. The same is possible when users
zoom into a particular part in the search space -- only those
films that appear during that range of years and are in the particular
popularity range will be part of the Alphaslider query range.
The Alphasliders can even affect each other, selecting Ingmar
Bergman on the Director slider would set the Actor slider to only
operate over those actors who appear in Ingmar Bergmanís
movies. This interaction between the query widgets, and the possibility
to use query results as input, creates a tightly coupled environment
where information can be explored in a rapid, safe, and comprehensible
Tools like the FilmFinder might be found in video
stores, libraries, and homes - they might even come as a part
of standard television sets. Imagine the Johnson family sitting
down at their TV Saturday night to watch a movie that they all
like. They turn on the TV and are presented with a FilmFinderís
starfield visualization and a number of controls [Color plate
1]. All controls are operable by a wireless mouse and no keyboard
The family members donít have a specific film
in mind, but they know that they want to see something popular
and recent. After some discussion they agree on the categories
for a search: drama, mystery, comedy, or an action film. To cut
down the number of films further they select an actor that they
all like, in this case Sean Connery. Observe in [Color plate 2]
how the category toggles have been manipulated - and the Alphaslider
indexes updated to contain appropriate values, the visualization
has zoomed into the correct part of the information space, and
Sean Connery has been selected with the Actor slider.
Now the number of films in the starfield has been
cut down from about 2000 to 25 and the Johnsons decide to look
further at The Murder on the Orient Express. They select
it with their remote control and are presented with an information
card [Color plate 3]. The description and image remind the Johnsons
that they have already seen this film, so the information card
can now become the tool to further refine their search.
Mr. Johnson sees Anthony Perkinsí name and
decides he wants to see a movie starring Anthony Perkins, while
Mrs. Johnson wants to see a movie with Ingrid Bergman. To resolve
the disagreement they select both actors in the information card,
and the selection is reflected in the Alphaslider settings. When
the information card is closed, the query result is updated and
the Johnsons are presented with one movie with both Anthony Perkins
and Ingrid Bergman which they decide to watch [Color plate 4].
The dynamic queries approach has much to recommend
it, but it must be extended to deal with larger databases, more
varied kinds of information, and a greater range of query types.
Current dynamic queries do not satisfy the demands of relational
completeness, but they offer other features that depend on spatial
output that are not available in existing relational databases.
It appears productive to combine the strengths of both approaches.
When searching films - as well as for other information
- it would be desirable to incorporate fuzzy searching to find
similar films. To include such functionality in the FilmFinder
would probably be desirable - but first algorithms must be devised
and more importantly, the issue of to what extent the mechanisms
should be user controlled must be examined.
When browsing the information space by zooming, it
is important that this is done smoothly so users get a feeling
of flying through the data. New algorithms and data structures
are necessary to support the smooth flying through the data. A
natural extension would be to add a third dimension so that some
films would appear closer than others.
The tight coupling among query components in the
FilmFinder was helpful - but there may be cases when such interrelationships
not are desirable. Formal specification of the logical propositions
for display invariants is a useful direction, because it could
lead to proofs of correctness and advanced tools to build such
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