teract with objects in everyday life, as
evolution and education taught us. Because we have all developed in different environments, individual gestures
may vary.
The main point we have to face
when designing for gestural interfaces:
Are these interfaces natural only in
the sense they offer a higher degree of
freedom and expression power, when
compared with a mouse-and-keyboard
interface? Or, are we really aiming at
empowering users with a means to
communicate with computer systems
so they feel more familiar with them?
Recently, Don Norman claimed that
“natural user interfaces are not natural,” 4 assuming they do not follow basic
rules of interaction design. We also believe they cannot be, currently, called
natural. Conversely, our criticism lies
on reflections on cultural aspects.
Users should not have to learn an
artificial gestural language created
by designers and that depends on the
device or even on the application. In
this context, each company defined its
guidelines for gestural interfaces, in
an attempt to stand out as a de facto
standard. Imposing a standard, especially when it is about cultural topics
(such as gestures), can easily fail due
to natural differences among human
beings: for example, think about the
Esperanto language, which failed to be
widely adopted because of its artificiality. Technology is an interesting aspect
to consider because, even if a gesture
is not the most natural one, it can become natural due to the widespread use
of technology adopting it. But, again,
when it comes to cultural issues this
can be quite difficult, as in the case of
the English language, which is imposed
as the de facto standard. Nevertheless,
non-native speakers will always encounter difficulties in being proficient.
Consider the tabletop multi-touch
environment in which moving the first
finger of each hand away from each
other is mapped into the “zoom” action. Is this natural or just an arbitrary
gesture, easy to recognize and learn?
Have you ever seen a person make
that gesture while speaking with another person? While we interact with
new technologies in a similar way we
interact with the real environment,
new natural interaction systems do
not take into account the spontaneity
The main aim
of natural interfaces
should be to break
down the technology-
driven approach
to interaction.
of the users—actually they inhibit the
way users naturally interact, because
they force them to adopt a static and
already defined set of command gestures. In their pioneering work with
the Charade system, Baudel and Beaudouin-Lafon1 partially faced this quandary. They avowed that problems with
gestural interfaces arose because users
must know the set of gestures allowed
by the system. For this reason they recommended that “gestural commands
should be simple, natural, and consistent.” However, this does not represent
a real solution to the problem, as users
were not free to interact naturally but
once again they were forced to learn an
artificial gesture vocabulary. Furthermore, in real scenarios the appropriate
gesture depends also on the context,
domain, cultural background, and
even ethics and human values. 2
interpreting Gestures
From our everyday life we know the
same meaning can be expressed by different gestures: for example, a handshake is a universal sign of friendliness, but only if our universe is limited
to the occidental world. In India, the
common way to greet someone is by
pressing your hands together, palms
touching and fingers pointed upward,
in front of the chest (the Añjali mudra).
Vice versa, the same gesture can have a
different meaning depending on cultural context: the thumbs-up sign in
America and most Western countries
means something is OK, or that you approve. This sign is interpreted as rude
in many Asian and Islamic countries.
The intended goal of gestural inter-
faces is to provide users with an intui-
tive way to interact so that, ideally, no
learning or training for specific ges-
ture/action mappings is required. Nev-
ertheless, current interactive gestural
languages are defined in a laboratory
setting and so, even if they can be ad-
opted in preliminary investigation,
they do not accurately define users’ be-
havior. This situation is similar to the
one that emerged in the past when we
shifted from command lines to graphi-
cal user interfaces. The main factor
driving this paradigm shift was, in fact,
a human factor on fostering recogni-
tion rather than recall. For most peo-
ple, it is easier to recognize an icon and
associate it with an action on an inter-
face than it is to recall a command be-
longing to a specific language that had
to be learned. Of course, this is made
possible by the display interface, just
as touchscreens open new possibilities
for human-computer interaction.
