consequences. As a result,
means of providing feedback,
explicit hints as to possible
actions, and guides for how
they are to be conducted are
required. Because gestures are
unconstrained, they are apt to
be performed in an ambiguous
or uninterruptable manner, in
which case constructive feedback is required to allow the
person to learn the appropriate
manner of performance and to
understand what was wrong
with their action. As with all
systems, some undo mechanism
will be required in situations
where unintended actions or
interpretations of gestures create undesirable states. And
because gesturing is a natural,
automatic behavior, the system
must be tuned to avoid false
responses to movements that
were not intended to be system
inputs. Solving this problem
might accidentally cause more
misses, movements that were
intended to be interpreted,
but were not. Neither of these
situations is common with keyboard, touchpad, pens, or mouse
actions.
What do I conclude? Gestures
will form a valuable addition
to our repertoire of interaction
techniques, but they need time
to be better developed, for us to
understand how best to deploy
them, and for standard conventions to develop so the same
gestures mean the same things
in different systems. And we
need to develop the supporting
infrastructure to handle guides,
feedback, error correction, and
the other consequences of gestures, some of which can use
well-known procedures, some of
which will be novel.
Gesture and touch-based sys-
tems are already so well accept-
ed that I continually see people
making gestures to systems that
do not understand them: tap-
ping the screens of non-touch-
sensitive displays, pinching and
expanding the fingers or sliding
the finger across the screen
on systems that do not sup-
port these actions, and for that
matter, waving hands in front
of sinks that use old-fashioned
handles, not infrared sensors, to
dispense water.
About the Author Don Norman
wears many hats, including cofounder of
the Nielsen Norman group, professor at
Northwestern University, visiting professor
at KAIST (South Korea), and author. His
latest book, Living with Complexity, started
out as a series of essays in this magazine.
He lives at jnd.org.
doi: 10.1145/1744161.1744163
© 2010 ACM 1072-5220/10/0500 $10.00
