I am reminded of those
old comedies of people
in formal clothing at
auctions doing silent
bidding. One person
sneezes and thereby
purchases an unwanted
painting. A couple
argues, and as they
wave their hands
at one another, the
waving gets interpreted
as ever-escalating bids.
able to help understand why.
The requisite feedback is lacking. Moreover, a pure gestural
system makes it difficult to
discover the set of possibilities
and the precise dynamics of
execution. These problems can
be overcome, of course, but only
by adding conventional interface
elements, such as menus, help
systems, traces, tutorials, undo
operations, and other forms of
feedback and guides.
Are gestures a powerful mode
of interaction? Yes, I have no
doubt that gestures will find
an appropriate place in the rep-
ertoire of interaction systems.
The main difference between
the systems of today and those
developed over the past 50
years is the rise of powerful,
inexpensive technologies for
sensors and processing, which
makes it now practical to deploy
these systems on inexpensive,
mass-produced items. We have
already seen great advances in
their use. Gestures will become
standardized, either by a formal
standards body or simply by
convention—for example, the
rapid zigzag stroke to indicate
crossing out or the upward lift
of the hands to indicate more
(sound, action, amplitude, etc.).
Shaking a device is starting to
mean “provide another alter-
native.” A horizontal wiping
motion of the fingers means to
go to a new page. Pinching or
expanding the placement of two
fingers contracts or expands a
displayed image. Indeed, many
of these were present in some
of the earliest developments
of gestural systems. Note that
gestures already incorporate
lessons learned from GUI devel-
opment. Thus, dragging two
fingers downward causes the
screen image to move upward,
keeping with the customary GUI
metaphor that one is moving the
viewing window, not the items
themselves.
