move closer to an object to see it in
more detail and to move away to see
the larger context. It is important
to realize that while geometric scaling is natural and provides multiple
cognitive benefits, e.g., helping to
maintain object permanence as one
moves in a space, computationally
based forms of interaction can be
designed that provide the ability to
interact directly with semantically
meaningful aspects of tasks. If one
focuses only on mimicking the physics of the world, one isn’t led to consider how to improve on such physics nor to develop physics for interacting with conceptual aspects of
domains. Just as snap dragging facilitates the task of grid layout, semantic zooming goes beyond simple geometric zooming to allow navigation
in the multiple semantic coordinate
systems of meaningful tasks. Rather
than just changes in geometric scale,
zooming can reveal a progression of
semantic views, each with a physics
of interaction particularly appropriate to that level. The key difference,
and I think fundamental insight, is
that computation enables design of
physics not only to exploit our abilities and minimize our weaknesses,
but also to allow us to directly interact with the semantic levels of tasks.
Computationally based physics can
not only mimic the physics of the
world and thus exploit our knowledge of the world; they can also
operate in ways that better match
The early work of Furnas on
generalized fish-eye views was
especially influential for me and
remains exceptionally relevant [ 15].
One deep insight was that instead
of mimicking the physics of optics,
a computationally based lens could
compute a degree of interest function to determine what information is to be visible and at what
scale. This, for me, is the canonical
of Bellcore lawyers and their concern about commercial systems named ART. We told folks that the
“ 3” was silent and continued to pronounce it as ART.
[ 9] Witkin, A., Gleicher, M., and Welch, W. Interactive
dynamics. SIGGRAPH Comput. Graph. 24, 2 (1990),
[ 10] Perlin, K., and Fox, D. Pad: An alternative
approach to the computer interface. Proc. of the
20th annual Conference on Computer Graphics and
Interactive Techniques (Anaheim, CA, Aug. 2-6).
ACM, New York, 1993, 57–64.
[ 11] In the 3-D system we provided navigation via
a mouse in the dominant hand and a six-degrees-of-freedom spaceball device in the non-dominant
hand but still confronted classic 3-D navigation
[ 12] Furnas, G. W. Generalized fisheye views. CHI
‘86: Proc. of the SIGCHI conference on Human
factors in computing systems. (Boston, MA, April
13-17). ACM, New York, 1986, 16–23.
[ 13] Bederson, B.B., and Hollan, J.D. Pad++: A
zooming graphical interface for exploring alternate interface physics. Proc. of the 7th Annual
ACM Symposium on User Interface Software and
Technology. ( Marina del Rey, CA, Nov. 2-4). ACM,
New York,1994, 17– 26.
[ 14] Bederson, B.B., Hollan, J.D., Perlin, K., Meyer,
J., Bacon, D., and Furnas, G. Pad++: A zoom-able graphical sketchpad for exploring alternate
interface physics. Journal of Visual Languages and
Computing 7 (1996), 3–31.
[ 15] Furnas, G. W. A Fisheye Follow-up: Further
reflections on focus + context. CHI ‘06 Proc. of the
SIGCHI Conference on Human Factors in Computing
Systems (Montreal, Canada, April 24-27). ACM, New
York, 2006, 999–1008.
description and first example of
semantic zooming. More important,
and one of the reasons I am drawn
to a physics characterization, is that
not only can what we see be computed to be appropriate to various
tasks but how we can interact can
also be dynamically adjusted to task
and context. Just as collaborative
filtering (note that the PageRank
algorithm is really a generalized
fish-eye degree of interest function)
coupled with massive computational power has radically improved
the way we search, we need to
explore how all important tasks can
be improved and restructured by
the design of cognitively convivial
physics of interaction. Zooming
and especially semantic zooming
provides a glimpse of one dimension of this future design space.
January + February 2011
[ 1] Ludwick Fleck gives a wonderful and amazing
example of the history of an idea in The Genesis
and Development of a Scientific Fact. University of
Chicago Press, Chicago, 1979.
[ 2] Hollan, J.D., Hutchins, E., and Weitzman, L.
Steamer: An interactive inspectable simulation-based training system. AI Magazine (1984), 15–27.
[ 3] Moboard was a computer-based training system for radar navigation that Ed Hutchins and I
designed. It incorporated insights from Ed’s earlier
ethnographic studies, a graphical micro-world in
which the student could explore the relationships
between relative and absolute motion, and a tutorial
facility that allowed the student to move step-by-step through radar navigation procedures. This
system reduced the failure rate in radar navigation
courses from 30 to about 3 percent at the Operation
Specialist School in San Diego, CA. A reworked version of this program subsequently became standard
refresher training for radar navigation aboard every
ship in the U.S. Navy.
[ 4] Hollan, J., Rich, E., Hill, W., Wroblewski, D.,
Wilner, W., Wittenburg, K., and Grudin, J. An introduction to HITS: Human Interface Tool Suite. In
Intelligent User Interfaces. S. Tyler and J. Sullivan,
eds. ACM, New York, 1991, 293–337.
[ 5] Hutchins, E.L., Hollan, J.D., and Norman, D. A.
Direct manipulation interfaces. Human Computer
Interaction 1, 4 (1985), 311–338.
[ 6] Shneiderman, B. Direct manipulation: A step
beyond programming languages. Computer 16, 8
[ 7] Card, S.K., Robertson, G.G., and Mackinlay,
J.D. The information visualizer, an information
workspace. CHI ‘91 Proc. of the SIGCHI conference
on Human factors in computing systems: Reaching
through technology ( New Orleans, LA, April 28-May
2). ACM, New York, 1991, 181–186.
[ 8] We changed the name to AR3T at the insistence
About the Author
Jim Hollan is professor of cog-
nitive science at the University
of California, San Diego. He
co-directs the Distributed
Cognition and Human-
Computer Interaction Lab with Ed Hutchins and
the ubiquitous computing and social dynamics
research group with Bill Griswold and Barry
Brown. His research explores the cognitive con-
sequences of computationally-based media,
with interests spanning across cognitive eth-
nography, distributed and embodied cognition,
human-computer interaction, multiscale infor-
mation visualization, multimodal interaction,
and software tools for visualization and interac-
tion. His current work involves three intertwined
activities: developing theory and methods,
designing and implementing prototypes, and
evaluating the effectiveness of systems to
understand the broader design space in which
they are situated. He is a member of the ACM
CHI Academy and in the past led the Intelligent
Systems group at NPRDC and UCSD, directed
the HCI Lab at MCC and the computer graph-
ics and interactive media research group at
Bellcore, and served as chair of computer sci-
ence at the University of New Mexico.
© 2011 ACM 1072-5220/11/0100 $10.00